Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
ype is >> > >> "TIMESTAMP >> > >>> WITH LOCAL TIME ZONE", and converting it to unix timestamp will >> > consider >> > >>> the session timezone, which is the expected result. But it's >> > inconvenient >> > >>> for users. >> > >>> >> > >>> Taking this a special case, and converting "TIMESTAMP '2023-04-27 >> > >>> 00:00:00'" to a unix timestamp with session timezone, will be >> > convenient >> > >>> for users, but will break the standard. I will +0.5 for this choice. >> > >>> >> > >>> yuxia 于2023年6月7日周三 12:06写道： >> > >>> >> > >>>> Hi, Feng Jin. >> > >>>> I think the concern of Leonard may be the inconsistency of the >> > behavior >> > >>> of >> > >>>> TIMESTAMP '2023-04-27 00:00:00' beween timetravel and other sql >> > >>> statement. >> > >>>> >> > >>>> For the normal sql: >> > >>>> `SELECT TIMESTAMP '2023-04-27 00:00:00'`, we won't consider >> timezone. >> > >>>> But for the sql for timetravl: >> > >>>> `SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP >> '2023-04-27 >> > >>>> 00:00:00'`, we will consider the timezone and convert to UTC >> > timestamp. >> > >>>> >> > >>>> The concern is valid. But for time travel, most style of engines, >> > >>>> Spark[1], Hive[2], Trino[3] also do the time conversion with >> > >> considering >> > >>>> the seesion time zone. I think we can align them to avoid the >> > >>> inconsistency >> > >>>> to other engines and provide convenience for the external >> connectors >> > >>> while >> > >>>> integrating Flink's time travel API. >> > >>>> >> > >>>> Regarding the inconsistency, I think we can consider time-travel >> as a >> > >>>> specical case, and we do needs to highlight this in this FLIP. >> > >>>> As for "violate the restriction outlined in FLINK-21978[1]", since >> we >> > >>> cast >> > >>>> timestamp to epochMillis only for the internal use, and won't >> expose >> > it >> > >>> to >> > >>>> users, I don't think it will violate the restriction. >> > >>>> Btw, please add a brief desc to explain the meaning of the >> parameter >> > >>>> `timestamp` in method `CatalogBaseTable getTable(ObjectPath >> tablePath, >> > >>> long >> > >>>> timestamp)`. Maybe something like "timestamp of the table snapt, >> which >> > >> is >> > >>>> millseconds since 1970-01-01 00:00:00 UTC". >> > >>>> >> > >>>> [1] >> > >>>> >> > >>> >> > >> >> > >> https://github.com/apache/spark/blob/0ed48feab65f2d86f5dda3e16bd53f2f795f5bc5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TimeTravelSpec.scala#L56 >> > >>>> [2] >> > >>>> >> > >>> >> > >> >> > >> https://github.com/apache/hive/blob/f5e69dc38d7ff26c70be19adc9d1a3ae90dc4cf2/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L989 >> > >>>> [3] >> > >>>> >> > >>> >> > >> >> > >> https://github.com/trinodb/trino/blob/2433d9e60f1abb0d85c32374c1758525560e1a86/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java#L443 >> > >>>> >> > >>>> >> > >>>> Best regards, >> > >>>> Yuxia >> > >>>> >> > >>>> - 原始邮件 - >> > >>>> 发件人: "Feng Jin" >> > >>>> 收件人: "dev" >> > >>>> 发送时间: 星期二, 2023年 6 月 06日 下午 10:15:47 >> > >>>> 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode >> > >>>> >> > >>>> Hi everyone >> > >>>> >> > >>>> Thanks everyone for your input. >> > >>>> >> > >>>> >> > >>>> @Yun >> > >>>> >> >
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
gt; > >>>> > > >>>> > > >>>>> Since we always directly add overload methods into Catalog > > >> according > > >>>> to new requirements, which makes the interface bloated > > >>>> > > >>>> Your concern is valid. If we need to support the long type version > in > > >> the > > >>>> future, we may have to add another method "getTable(ObjectPath, long > > >>>> version)". However, I understand that > > >>>> "Catalog.getTable(tablePath).on(timeStamp)" may not meet the > > >>> requirements. > > >>>> The timestamp is for Catalog's use, and Catalog obtains the > > >> corresponding > > >>>> schema based on this time. > > >>>> > > >>>> > > >>>> @liu @Regards > > >>>> > > >>>> I am very sorry for the unclear description in the document. I have > > >>> updated > > >>>> relevant descriptions regarding why it needs to be implemented in > > >>> Catalog. > > >>>> > > >>>> Travel not only requires obtaining data at the corresponding time > > >> point, > > >>>> but also requires the corresponding Schema at that time point > > >>>> > > >>>> > > >>>> @Shammon > > >>>> > > >>>>> Flink or connector such as iceberg/paimon can create sources from > > >> the > > >>>> `CatalogBaseTable` directly without the need to get the snapshot ID > > >> from > > >>>> `CatalogTable.getSnapshot()`. What do you think of it? > > >>>> > > >>>> You are right, we don't need the getSnapshot interface for > > >> PaimonCatalog > > >>> or > > >>>> IcebergCatalog tables, but we may need it for temporary tables. > > >>>> > > >>>> > > >>>> > > >>>> Best, > > >>>> Feng > > >>>> > > >>>> > > >>>> On Tue, Jun 6, 2023 at 9:32 PM Feng Jin > > wrote: > > >>>> > > >>>>> Sorry I replied to the wrong mail. Please ignore the last email. > > >>>>> > > >>>>> > > >>>>> Hi Leonard > > >>>>> > > >>>>>> 1. Unification SQL > > >>>>> > > >>>>> I agree that it is crucial for us to support both batch and > streaming > > >>>>> processing. The current design allows for the support of both > batch > > >>> and > > >>>>> streaming processing. I'll update the FLIP later. > > >>>>> > > >>>>> > > >>>>>> 2.Semantics > > >>>>> > > >>>>> In my opinion, it would be feasible to perform the conversion based > > >> on > > >>>> the > > >>>>> current session time, regardless of whether it is TIMESTAMP or > > >>>>> TIMESTAMP_LTZ. > > >>>>> > > >>>>> However, this may indeed violate the restriction outlined in > > >>>>> FLINK-21978[1] as Benchao mentioned, and I am uncertain as to > > >> whether > > >>> it > > >>>>> is reasonable. > > >>>>> > > >>>>> > > >>>>>> 3. Some external systems may use timestamp value to mark a > > >>> version, > > >>>>> but others may use version number、file position、log offset. > > >>>>> > > >>>>> It is true that most systems support time-related operations, and I > > >>>>> believe that the current design is compatible with most systems. > > >>> However, > > >>>>> if we want to support long data type, it may require Calcite to > > >> support > > >>>> the > > >>>>> VERSION AS OF syntax. I understand that this is something that we > may > > >>>> need > > >>>>> to consider in the future. > > >>>>> > > >>>>> > > >>>>> Best, > > >>>>> Feng > > >>>>> > > >>>>> [1] https://issu
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
-- > >> 0 > >> > >> Flink SQL> SET 'table.local-time-zone' = 'Asia/Shanghai'; > >> Flink SQL> SELECT UNIX_TIMESTAMP(CAST(TIMESTAMP '1970-01-01 00:00:00' as > >> STRING)) as `timestamp`; > >> --- > >> timestamp > >> -- > >> -28800 > >> > >> Therefore, the current conversion method exposed to users is also using > >> LOCAL TIME ZONE. > >> > >> > >> @yuxia > >> > >> Thank you very much for providing the list of behaviors of TIMESTAMP in > >> other systems. > >> > >>> I think we can align them to avoid the inconsistency to other engines > and > >> provide convenience for the external connectors while integrating > Flink's > >> time travel API. > >> > >> +1 for this. > >> > >>> Regarding the inconsistency, I think we can consider time-travel as a > >> specical case, and we do needs to highlight this in this FLIP. > >> As for "violate the restriction outlined in FLINK-21978[1]", since we > cast > >> timestamp to epochMillis only for the internal use, and won't expose it > to > >> users, I don't think it will violate the restriction. > >> Btw, please add a brief desc to explain the meaning of the parameter > >> `timestamp` in method `CatalogBaseTable getTable(ObjectPath tablePath, > long > >> timestamp)`. Maybe something like "timestamp of the table snapt, which > is > >> millseconds since 1970-01-01 00:00:00 UTC". > >> > >> Thank you for the suggestions regarding the document. I will add them to > >> FLIP. > >> > >> > >> Best, > >> Feng > >> > >> > >> On Wed, Jun 7, 2023 at 12:18 PM Benchao Li > wrote: > >> > >>> I also share the concern about the timezone problem. > >>> > >>> The type for "TIMESTAMP '2023-04-27 00:00:00'" should be "TIMESTAMP > >> WITHOUT > >>> TIME ZONE", converting it to unix timestamp would use UTC timezone, > which > >>> is not usually expected by users. > >>> > >>> If we want to keep consistent with the standard, we probably should use > >>> "TIMESTAMP WITH LOCAL ZONE '2023-04-27 00:00:00'", which type is > >> "TIMESTAMP > >>> WITH LOCAL TIME ZONE", and converting it to unix timestamp will > consider > >>> the session timezone, which is the expected result. But it's > inconvenient > >>> for users. > >>> > >>> Taking this a special case, and converting "TIMESTAMP '2023-04-27 > >>> 00:00:00'" to a unix timestamp with session timezone, will be > convenient > >>> for users, but will break the standard. I will +0.5 for this choice. > >>> > >>> yuxia 于2023年6月7日周三 12:06写道： > >>> > >>>> Hi, Feng Jin. > >>>> I think the concern of Leonard may be the inconsistency of the > behavior > >>> of > >>>> TIMESTAMP '2023-04-27 00:00:00' beween timetravel and other sql > >>> statement. > >>>> > >>>> For the normal sql: > >>>> `SELECT TIMESTAMP '2023-04-27 00:00:00'`, we won't consider timezone. > >>>> But for the sql for timetravl: > >>>> `SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP '2023-04-27 > >>>> 00:00:00'`, we will consider the timezone and convert to UTC > timestamp. > >>>> > >>>> The concern is valid. But for time travel, most style of engines, > >>>> Spark[1], Hive[2], Trino[3] also do the time conversion with > >> considering > >>>> the seesion time zone. I think we can align them to avoid the > >>> inconsistency > >>>> to other engines and provide convenience for the external connectors > >>> while > >>>> integrating Flink's time travel API. > >>>> > >>>> Regarding the inconsistency, I think we can consider time-travel as a > >>>> specical case, and we do needs to highlight this in this FLIP. > >>>> As for "violate the restriction outlined in FLINK-21978[1]", since we > >>> cast > >>>> timestamp to epochMillis only for the internal use, and won't expose > it > >>> to > >>>> users, I don't think it will violate the restriction. > >>>> Btw, please add a brief desc to explain the meaning
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
integrating Flink's >> time travel API. >> >> +1 for this. >> >>> Regarding the inconsistency, I think we can consider time-travel as a >> specical case, and we do needs to highlight this in this FLIP. >> As for "violate the restriction outlined in FLINK-21978[1]", since we cast >> timestamp to epochMillis only for the internal use, and won't expose it to >> users, I don't think it will violate the restriction. >> Btw, please add a brief desc to explain the meaning of the parameter >> `timestamp` in method `CatalogBaseTable getTable(ObjectPath tablePath, long >> timestamp)`. Maybe something like "timestamp of the table snapt, which is >> millseconds since 1970-01-01 00:00:00 UTC". >> >> Thank you for the suggestions regarding the document. I will add them to >> FLIP. >> >> >> Best, >> Feng >> >> >> On Wed, Jun 7, 2023 at 12:18 PM Benchao Li wrote: >> >>> I also share the concern about the timezone problem. >>> >>> The type for "TIMESTAMP '2023-04-27 00:00:00'" should be "TIMESTAMP >> WITHOUT >>> TIME ZONE", converting it to unix timestamp would use UTC timezone, which >>> is not usually expected by users. >>> >>> If we want to keep consistent with the standard, we probably should use >>> "TIMESTAMP WITH LOCAL ZONE '2023-04-27 00:00:00'", which type is >> "TIMESTAMP >>> WITH LOCAL TIME ZONE", and converting it to unix timestamp will consider >>> the session timezone, which is the expected result. But it's inconvenient >>> for users. >>> >>> Taking this a special case, and converting "TIMESTAMP '2023-04-27 >>> 00:00:00'" to a unix timestamp with session timezone, will be convenient >>> for users, but will break the standard. I will +0.5 for this choice. >>> >>> yuxia 于2023年6月7日周三 12:06写道： >>> >>>> Hi, Feng Jin. >>>> I think the concern of Leonard may be the inconsistency of the behavior >>> of >>>> TIMESTAMP '2023-04-27 00:00:00' beween timetravel and other sql >>> statement. >>>> >>>> For the normal sql: >>>> `SELECT TIMESTAMP '2023-04-27 00:00:00'`, we won't consider timezone. >>>> But for the sql for timetravl: >>>> `SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP '2023-04-27 >>>> 00:00:00'`, we will consider the timezone and convert to UTC timestamp. >>>> >>>> The concern is valid. But for time travel, most style of engines, >>>> Spark[1], Hive[2], Trino[3] also do the time conversion with >> considering >>>> the seesion time zone. I think we can align them to avoid the >>> inconsistency >>>> to other engines and provide convenience for the external connectors >>> while >>>> integrating Flink's time travel API. >>>> >>>> Regarding the inconsistency, I think we can consider time-travel as a >>>> specical case, and we do needs to highlight this in this FLIP. >>>> As for "violate the restriction outlined in FLINK-21978[1]", since we >>> cast >>>> timestamp to epochMillis only for the internal use, and won't expose it >>> to >>>> users, I don't think it will violate the restriction. >>>> Btw, please add a brief desc to explain the meaning of the parameter >>>> `timestamp` in method `CatalogBaseTable getTable(ObjectPath tablePath, >>> long >>>> timestamp)`. Maybe something like "timestamp of the table snapt, which >> is >>>> millseconds since 1970-01-01 00:00:00 UTC". >>>> >>>> [1] >>>> >>> >> https://github.com/apache/spark/blob/0ed48feab65f2d86f5dda3e16bd53f2f795f5bc5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TimeTravelSpec.scala#L56 >>>> [2] >>>> >>> >> https://github.com/apache/hive/blob/f5e69dc38d7ff26c70be19adc9d1a3ae90dc4cf2/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L989 >>>> [3] >>>> >>> >> https://github.com/trinodb/trino/blob/2433d9e60f1abb0d85c32374c1758525560e1a86/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java#L443 >>>> >>>> >>>> Best regards, >>>> Yuxia >>>> >>>> - 原始邮件 - >>>> 发件人: "Feng Jin" >>>> 收件人: "dev" >>>> 发送时间: 星期二, 2023年 6 月 06日 下午 10:15:47
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
ESTAMP '2023-04-27 00:00:00'`, we won't consider timezone. > > > But for the sql for timetravl: > > > `SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP '2023-04-27 > > > 00:00:00'`, we will consider the timezone and convert to UTC timestamp. > > > > > > The concern is valid. But for time travel, most style of engines, > > > Spark[1], Hive[2], Trino[3] also do the time conversion with > considering > > > the seesion time zone. I think we can align them to avoid the > > inconsistency > > > to other engines and provide convenience for the external connectors > > while > > > integrating Flink's time travel API. > > > > > > Regarding the inconsistency, I think we can consider time-travel as a > > > specical case, and we do needs to highlight this in this FLIP. > > > As for "violate the restriction outlined in FLINK-21978[1]", since we > > cast > > > timestamp to epochMillis only for the internal use, and won't expose it > > to > > > users, I don't think it will violate the restriction. > > > Btw, please add a brief desc to explain the meaning of the parameter > > > `timestamp` in method `CatalogBaseTable getTable(ObjectPath tablePath, > > long > > > timestamp)`. Maybe something like "timestamp of the table snapt, which > is > > > millseconds since 1970-01-01 00:00:00 UTC". > > > > > > [1] > > > > > > https://github.com/apache/spark/blob/0ed48feab65f2d86f5dda3e16bd53f2f795f5bc5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TimeTravelSpec.scala#L56 > > > [2] > > > > > > https://github.com/apache/hive/blob/f5e69dc38d7ff26c70be19adc9d1a3ae90dc4cf2/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L989 > > > [3] > > > > > > https://github.com/trinodb/trino/blob/2433d9e60f1abb0d85c32374c1758525560e1a86/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java#L443 > > > > > > > > > Best regards, > > > Yuxia > > > > > > - 原始邮件 - > > > 发件人: "Feng Jin" > > > 收件人: "dev" > > > 发送时间: 星期二, 2023年 6 月 06日 下午 10:15:47 > > > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > > > > > Hi everyone > > > > > > Thanks everyone for your input. > > > > > > > > > @Yun > > > > > > > I think you could add descriptions of how to align backfill time > > travel > > > with querying the latest data. And I think you should also update the > > > "Discussion thread" in the original FLIP. > > > > > > Thank you for the suggestion, I will update it in the document. > > > > > > > I have a question about getting the table schema from the catalog. > I'm > > > not sure whether the Catalog#getTable(tablePath, timestamp) will be > > called > > > only once. > > > > > > I understand that in a query, the schema of the table is determined > > before > > > execution. The schema used will be based on the latest schema within > the > > > TimeTravel period. > > > > > > In addition, due to current syntax limitations, we are unable to > support > > > the use of BETWEEN AND. > > > > > > > > > @Jing > > > > > > > Would you like to update your thoughts described in your previous > > email > > > about why SupportsTimeTravel has been rejected into the FLIP? > > > > > > Sure, I updated the doc. > > > > > > > > > >Since we always directly add overload methods into Catalog > according > > > to new requirements, which makes the interface bloated > > > > > > Your concern is valid. If we need to support the long type version in > the > > > future, we may have to add another method "getTable(ObjectPath, long > > > version)". However, I understand that > > > "Catalog.getTable(tablePath).on(timeStamp)" may not meet the > > requirements. > > > The timestamp is for Catalog's use, and Catalog obtains the > corresponding > > > schema based on this time. > > > > > > > > > @liu @Regards > > > > > > I am very sorry for the unclear description in the document. I have > > updated > > > relevant descriptions regarding why it needs to be implemented in > > Catalog. > > > > > > Travel not only requires obtaining data at the corre
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
tps://github.com/apache/spark/blob/0ed48feab65f2d86f5dda3e16bd53f2f795f5bc5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TimeTravelSpec.scala#L56 > > [2] > > > https://github.com/apache/hive/blob/f5e69dc38d7ff26c70be19adc9d1a3ae90dc4cf2/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L989 > > [3] > > > https://github.com/trinodb/trino/blob/2433d9e60f1abb0d85c32374c1758525560e1a86/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java#L443 > > > > > > Best regards, > > Yuxia > > > > - 原始邮件 - > > 发件人: "Feng Jin" > > 收件人: "dev" > > 发送时间: 星期二, 2023年 6 月 06日 下午 10:15:47 > > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > > > Hi everyone > > > > Thanks everyone for your input. > > > > > > @Yun > > > > > I think you could add descriptions of how to align backfill time > travel > > with querying the latest data. And I think you should also update the > > "Discussion thread" in the original FLIP. > > > > Thank you for the suggestion, I will update it in the document. > > > > > I have a question about getting the table schema from the catalog. I'm > > not sure whether the Catalog#getTable(tablePath, timestamp) will be > called > > only once. > > > > I understand that in a query, the schema of the table is determined > before > > execution. The schema used will be based on the latest schema within the > > TimeTravel period. > > > > In addition, due to current syntax limitations, we are unable to support > > the use of BETWEEN AND. > > > > > > @Jing > > > > > Would you like to update your thoughts described in your previous > email > > about why SupportsTimeTravel has been rejected into the FLIP? > > > > Sure, I updated the doc. > > > > > > >Since we always directly add overload methods into Catalog according > > to new requirements, which makes the interface bloated > > > > Your concern is valid. If we need to support the long type version in the > > future, we may have to add another method "getTable(ObjectPath, long > > version)". However, I understand that > > "Catalog.getTable(tablePath).on(timeStamp)" may not meet the > requirements. > > The timestamp is for Catalog's use, and Catalog obtains the corresponding > > schema based on this time. > > > > > > @liu @Regards > > > > I am very sorry for the unclear description in the document. I have > updated > > relevant descriptions regarding why it needs to be implemented in > Catalog. > > > > Travel not only requires obtaining data at the corresponding time point, > > but also requires the corresponding Schema at that time point > > > > > > @Shammon > > > > > Flink or connector such as iceberg/paimon can create sources from the > > `CatalogBaseTable` directly without the need to get the snapshot ID from > > `CatalogTable.getSnapshot()`. What do you think of it? > > > > You are right, we don't need the getSnapshot interface for PaimonCatalog > or > > IcebergCatalog tables, but we may need it for temporary tables. > > > > > > > > Best, > > Feng > > > > > > On Tue, Jun 6, 2023 at 9:32 PM Feng Jin wrote: > > > > > Sorry I replied to the wrong mail. Please ignore the last email. > > > > > > > > > Hi Leonard > > > > > > > 1. Unification SQL > > > > > > I agree that it is crucial for us to support both batch and streaming > > > processing. The current design allows for the support of both batch > and > > > streaming processing. I'll update the FLIP later. > > > > > > > > > > 2.Semantics > > > > > > In my opinion, it would be feasible to perform the conversion based on > > the > > > current session time, regardless of whether it is TIMESTAMP or > > > TIMESTAMP_LTZ. > > > > > > However, this may indeed violate the restriction outlined in > > > FLINK-21978[1] as Benchao mentioned, and I am uncertain as to whether > it > > > is reasonable. > > > > > > > > > > 3. Some external systems may use timestamp value to mark a > version, > > > but others may use version number、file position、log offset. > > > > > > It is true that most systems support time-related operations, and I > > > believe that the current design is compatible with
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
I also share the concern about the timezone problem. The type for "TIMESTAMP '2023-04-27 00:00:00'" should be "TIMESTAMP WITHOUT TIME ZONE", converting it to unix timestamp would use UTC timezone, which is not usually expected by users. If we want to keep consistent with the standard, we probably should use "TIMESTAMP WITH LOCAL ZONE '2023-04-27 00:00:00'", which type is "TIMESTAMP WITH LOCAL TIME ZONE", and converting it to unix timestamp will consider the session timezone, which is the expected result. But it's inconvenient for users. Taking this a special case, and converting "TIMESTAMP '2023-04-27 00:00:00'" to a unix timestamp with session timezone, will be convenient for users, but will break the standard. I will +0.5 for this choice. yuxia 于2023年6月7日周三 12:06写道： > Hi, Feng Jin. > I think the concern of Leonard may be the inconsistency of the behavior of > TIMESTAMP '2023-04-27 00:00:00' beween timetravel and other sql statement. > > For the normal sql: > `SELECT TIMESTAMP '2023-04-27 00:00:00'`, we won't consider timezone. > But for the sql for timetravl: > `SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP '2023-04-27 > 00:00:00'`, we will consider the timezone and convert to UTC timestamp. > > The concern is valid. But for time travel, most style of engines, > Spark[1], Hive[2], Trino[3] also do the time conversion with considering > the seesion time zone. I think we can align them to avoid the inconsistency > to other engines and provide convenience for the external connectors while > integrating Flink's time travel API. > > Regarding the inconsistency, I think we can consider time-travel as a > specical case, and we do needs to highlight this in this FLIP. > As for "violate the restriction outlined in FLINK-21978[1]", since we cast > timestamp to epochMillis only for the internal use, and won't expose it to > users, I don't think it will violate the restriction. > Btw, please add a brief desc to explain the meaning of the parameter > `timestamp` in method `CatalogBaseTable getTable(ObjectPath tablePath, long > timestamp)`. Maybe something like "timestamp of the table snapt, which is > millseconds since 1970-01-01 00:00:00 UTC". > > [1] > https://github.com/apache/spark/blob/0ed48feab65f2d86f5dda3e16bd53f2f795f5bc5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TimeTravelSpec.scala#L56 > [2] > https://github.com/apache/hive/blob/f5e69dc38d7ff26c70be19adc9d1a3ae90dc4cf2/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L989 > [3] > https://github.com/trinodb/trino/blob/2433d9e60f1abb0d85c32374c1758525560e1a86/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java#L443 > > > Best regards, > Yuxia > > - 原始邮件 - > 发件人: "Feng Jin" > 收件人: "dev" > 发送时间: 星期二, 2023年 6 月 06日 下午 10:15:47 > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > Hi everyone > > Thanks everyone for your input. > > > @Yun > > > I think you could add descriptions of how to align backfill time travel > with querying the latest data. And I think you should also update the > "Discussion thread" in the original FLIP. > > Thank you for the suggestion, I will update it in the document. > > > I have a question about getting the table schema from the catalog. I'm > not sure whether the Catalog#getTable(tablePath, timestamp) will be called > only once. > > I understand that in a query, the schema of the table is determined before > execution. The schema used will be based on the latest schema within the > TimeTravel period. > > In addition, due to current syntax limitations, we are unable to support > the use of BETWEEN AND. > > > @Jing > > > Would you like to update your thoughts described in your previous email > about why SupportsTimeTravel has been rejected into the FLIP? > > Sure, I updated the doc. > > > >Since we always directly add overload methods into Catalog according > to new requirements, which makes the interface bloated > > Your concern is valid. If we need to support the long type version in the > future, we may have to add another method "getTable(ObjectPath, long > version)". However, I understand that > "Catalog.getTable(tablePath).on(timeStamp)" may not meet the requirements. > The timestamp is for Catalog's use, and Catalog obtains the corresponding > schema based on this time. > > > @liu @Regards > > I am very sorry for the unclear description in the document. I have updated > relevant descriptions regarding why it needs to be implemented in Catalog. > > Travel not only requires obtaining data at the corresponding t
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi, Feng Jin. I think the concern of Leonard may be the inconsistency of the behavior of TIMESTAMP '2023-04-27 00:00:00' beween timetravel and other sql statement. For the normal sql: `SELECT TIMESTAMP '2023-04-27 00:00:00'`, we won't consider timezone. But for the sql for timetravl: `SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP '2023-04-27 00:00:00'`, we will consider the timezone and convert to UTC timestamp. The concern is valid. But for time travel, most style of engines, Spark[1], Hive[2], Trino[3] also do the time conversion with considering the seesion time zone. I think we can align them to avoid the inconsistency to other engines and provide convenience for the external connectors while integrating Flink's time travel API. Regarding the inconsistency, I think we can consider time-travel as a specical case, and we do needs to highlight this in this FLIP. As for "violate the restriction outlined in FLINK-21978[1]", since we cast timestamp to epochMillis only for the internal use, and won't expose it to users, I don't think it will violate the restriction. Btw, please add a brief desc to explain the meaning of the parameter `timestamp` in method `CatalogBaseTable getTable(ObjectPath tablePath, long timestamp)`. Maybe something like "timestamp of the table snapt, which is millseconds since 1970-01-01 00:00:00 UTC". [1] https://github.com/apache/spark/blob/0ed48feab65f2d86f5dda3e16bd53f2f795f5bc5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TimeTravelSpec.scala#L56 [2] https://github.com/apache/hive/blob/f5e69dc38d7ff26c70be19adc9d1a3ae90dc4cf2/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L989 [3] https://github.com/trinodb/trino/blob/2433d9e60f1abb0d85c32374c1758525560e1a86/plugin/trino-iceberg/src/main/java/io/trino/plugin/iceberg/IcebergMetadata.java#L443 Best regards, Yuxia - 原始邮件 - 发件人: "Feng Jin" 收件人: "dev" 发送时间: 星期二, 2023年 6 月 06日 下午 10:15:47 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode Hi everyone Thanks everyone for your input. @Yun > I think you could add descriptions of how to align backfill time travel with querying the latest data. And I think you should also update the "Discussion thread" in the original FLIP. Thank you for the suggestion, I will update it in the document. > I have a question about getting the table schema from the catalog. I'm not sure whether the Catalog#getTable(tablePath, timestamp) will be called only once. I understand that in a query, the schema of the table is determined before execution. The schema used will be based on the latest schema within the TimeTravel period. In addition, due to current syntax limitations, we are unable to support the use of BETWEEN AND. @Jing > Would you like to update your thoughts described in your previous email about why SupportsTimeTravel has been rejected into the FLIP? Sure, I updated the doc. >Since we always directly add overload methods into Catalog according to new requirements, which makes the interface bloated Your concern is valid. If we need to support the long type version in the future, we may have to add another method "getTable(ObjectPath, long version)". However, I understand that "Catalog.getTable(tablePath).on(timeStamp)" may not meet the requirements. The timestamp is for Catalog's use, and Catalog obtains the corresponding schema based on this time. @liu @Regards I am very sorry for the unclear description in the document. I have updated relevant descriptions regarding why it needs to be implemented in Catalog. Travel not only requires obtaining data at the corresponding time point, but also requires the corresponding Schema at that time point @Shammon > Flink or connector such as iceberg/paimon can create sources from the `CatalogBaseTable` directly without the need to get the snapshot ID from `CatalogTable.getSnapshot()`. What do you think of it? You are right, we don't need the getSnapshot interface for PaimonCatalog or IcebergCatalog tables, but we may need it for temporary tables. Best, Feng On Tue, Jun 6, 2023 at 9:32 PM Feng Jin wrote: > Sorry I replied to the wrong mail. Please ignore the last email. > > > Hi Leonard > > > 1. Unification SQL > > I agree that it is crucial for us to support both batch and streaming > processing. The current design allows for the support of both batch and > streaming processing. I'll update the FLIP later. > > > > 2.Semantics > > In my opinion, it would be feasible to perform the conversion based on the > current session time, regardless of whether it is TIMESTAMP or > TIMESTAMP_LTZ. > > However, this may indeed violate the restriction outlined in > FLINK-21978[1] as Benchao mentioned, and I am uncertain as to whether it > is reasonable. > > > > 3. Some external
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
w to >> align backfill time travel with querying the latest data. And I think you >> should also update the "Discussion thread" in the original FLIP. >> > >> > Moreover, I have a question about getting the table schema from the >> catalog. I'm not sure whether the Catalog#getTable(tablePath, timestamp) >> will be called only once. If we have a backfill query between 2023-05-29 >> and 2023-06-04 in the past week, and the table schema changed on >> 2023-06-01, will the query below detect the schema changes during backfill >> the whole week? >> > >> > SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP BETWEEN >> '2023-05-29 00:00:00' AND '2023-06-05 00:00:00' >> > >> > Best >> > Yun Tang >> > >> > >> > >> > From: Shammon FY >> > Sent: Thursday, June 1, 2023 17:57 >> > To: dev@flink.apache.org >> > Subject: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode >> > >> > Hi Feng, >> > >> > I have one minor comment about the public interface `Optional >> > getSnapshot()` in the `CatalogTable`. >> > >> > As we can get tables from the new method `Catalog.getTable(ObjectPath >> > tablePath, long timestamp)`, I think the returned `CatalogBaseTable` >> will >> > have the information of timestamp. Flink or connector such as >> > iceberg/paimon can create sources from the `CatalogBaseTable` directly >> > without the need to get the snapshot ID from >> `CatalogTable.getSnapshot()`. >> > What do you think of it? >> > >> > Best, >> > Shammon FY >> > >> > >> > On Thu, Jun 1, 2023 at 7:22 AM Jing Ge >> wrote: >> > >> >> Hi Feng, >> >> >> >> Thanks for the proposal! Very interesting feature. Would you like to >> update >> >> your thoughts described in your previous email about why >> SupportsTimeTravel >> >> has been rejected into the FLIP? This will help readers understand the >> >> context (in the future). >> >> >> >> Since we always directly add overload methods into Catalog according >> to new >> >> requirements, which makes the interface bloated. Just out of curiosity, >> >> does it make sense to introduce some DSL design? Like >> >> Catalog.getTable(tablePath).on(timeStamp), >> >> Catalog.getTable(tablePath).current() for the most current version, and >> >> more room for further extension like timestamp range, etc. I haven't >> read >> >> all the source code yet and I'm not sure if it is possible. But a >> >> design like this will keep the Catalog API lean and the API/DSL will be >> >> self described and easier to use. >> >> >> >> Best regards, >> >> Jing >> >> >> >> >> >> On Wed, May 31, 2023 at 12:08 PM Krzysztof Chmielewski < >> >> krzysiek.chmielew...@gmail.com> wrote: >> >> >> >>> Ok after second though I'm retracting my previous statement about >> Catalog >> >>> changes you proposed. >> >>> I do see a benefit for Delta connector actually with this change and >> see >> >>> why this could be coupled with Catalog. >> >>> >> >>> Delta Connector SQL support, also ships a Delta Catalog implementation >> >> for >> >>> Flink. >> >>> For Delta Catalog, table schema information is fetched from underlying >> >>> _delta_log and not stored in metastore. For time travel we actually >> had a >> >>> problem, that if we would like to timetravel back to some old version, >> >>> where schema was slightly different, then we would have a conflict >> since >> >>> Catalog would return current schema and not how it was for version X. >> >>> >> >>> With your change, our Delta Catalog can actually fetch schema for >> >> version X >> >>> and send it to DeltaTableFactory. Currency, Catalog can fetch only >> >> current >> >>> version. What we would also need however is version (number/timestamp) >> >> for >> >>> this table passed to DynamicTableFactory so we could properly set >> Delta >> >>> standalone library. >> >>> >> >>> Regards, >> >>> Krzysztof >> >>> >> >>> śr., 31 maj 2023 o 1
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Sorry I replied to the wrong mail. Please ignore the last email. Hi Leonard > 1. Unification SQL I agree that it is crucial for us to support both batch and streaming processing. The current design allows for the support of both batch and streaming processing. I'll update the FLIP later. > 2.Semantics In my opinion, it would be feasible to perform the conversion based on the current session time, regardless of whether it is TIMESTAMP or TIMESTAMP_LTZ. However, this may indeed violate the restriction outlined in FLINK-21978[1] as Benchao mentioned, and I am uncertain as to whether it is reasonable. > 3. Some external systems may use timestamp value to mark a version, but others may use version number、file position、log offset. It is true that most systems support time-related operations, and I believe that the current design is compatible with most systems. However, if we want to support long data type, it may require Calcite to support the VERSION AS OF syntax. I understand that this is something that we may need to consider in the future. Best, Feng [1] https://issues.apache.org/jira/browse/FLINK-21978 On Tue, Jun 6, 2023 at 8:28 PM Leonard Xu wrote: > Hi, Feng > > Thanks for driving this FLIP, very impressive feature that users want, > I’ve some quick questions here. > > 1.Unification SQL: > The snapshot concept exists both in Batch mode and Streaming > mode, could we consider a unified proposal? I think users won’t another > SQL syntax named > Time travel for Streaming mode. > > 2.Semantics: > Flink supports TIMESTAMP and TIMESTAMP_LTZ types, to get a long > timestamp value (getTable(ObjectPath tablePath, long timestamp)) we need > two information i.e. a TIMESTAMP value and current session timezone, how > we deal the value with current proposed SQL syntax. > > 3. Is it enough using sinlge timestamp to track a snapshot(version) of > external table? Some external systems may use timestamp value to mark a > version, but others may use version number、file position、log offset. > > Best, > Leonard > > > > > On Jun 5, 2023, at 3:28 PM, Yun Tang wrote: > > > > Hi Feng, > > > > I think this FLIP would provide one important feature to unify the > stream-SQL and batch-SQL when we backfill the historical data in batch mode. > > > > For the "Syntax" session, I think you could add descriptions of how to > align backfill time travel with querying the latest data. And I think you > should also update the "Discussion thread" in the original FLIP. > > > > Moreover, I have a question about getting the table schema from the > catalog. I'm not sure whether the Catalog#getTable(tablePath, timestamp) > will be called only once. If we have a backfill query between 2023-05-29 > and 2023-06-04 in the past week, and the table schema changed on > 2023-06-01, will the query below detect the schema changes during backfill > the whole week? > > > > SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP BETWEEN > '2023-05-29 00:00:00' AND '2023-06-05 00:00:00' > > > > Best > > Yun Tang > > > > > > > > From: Shammon FY > > Sent: Thursday, June 1, 2023 17:57 > > To: dev@flink.apache.org > > Subject: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > > > Hi Feng, > > > > I have one minor comment about the public interface `Optional > > getSnapshot()` in the `CatalogTable`. > > > > As we can get tables from the new method `Catalog.getTable(ObjectPath > > tablePath, long timestamp)`, I think the returned `CatalogBaseTable` will > > have the information of timestamp. Flink or connector such as > > iceberg/paimon can create sources from the `CatalogBaseTable` directly > > without the need to get the snapshot ID from > `CatalogTable.getSnapshot()`. > > What do you think of it? > > > > Best, > > Shammon FY > > > > > > On Thu, Jun 1, 2023 at 7:22 AM Jing Ge > wrote: > > > >> Hi Feng, > >> > >> Thanks for the proposal! Very interesting feature. Would you like to > update > >> your thoughts described in your previous email about why > SupportsTimeTravel > >> has been rejected into the FLIP? This will help readers understand the > >> context (in the future). > >> > >> Since we always directly add overload methods into Catalog according to > new > >> requirements, which makes the interface bloated. Just out of curiosity, > >> does it make sense to introduce some DSL design? Like > >> Catalog.getTable(tablePath).on(timeStamp), > >> Catalog.getTable(tablePath).cu
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi Leonard,
Thanks for your reply.
> 1. a How to construct a CatalogDescriptor ?
I think it would be helpful to add a method for constructing a
CatalogDescriptor, as you mentioned in 1.c. I will update the documentation
later.
> 1.b How to visit the fields ? Could we use Configuration instead of
Map ?
I believe that the use of Map options is only intended for
creating a catalog and not for accessing internal parameters.
Since all of the relevant parameters for CREATE CATALOG are also stored in
Map options, my understanding is that using Map options should suffice.
Here is the implementation of execute CREATE CATALOG statement.
```java
private TableResultInternal createCatalog(CreateCatalogOperation operation)
{
String exMsg = getDDLOpExecuteErrorMsg(operation.asSummaryString());
try {
String catalogName = operation.getCatalogName();
Map properties = operation.getProperties();
Catalog catalog =
FactoryUtil.createCatalog(
catalogName,
properties,
tableConfig,
resourceManager.getUserClassLoader());
catalogManager.registerCatalog(catalogName, catalog);
return TableResultImpl.TABLE_RESULT_OK;
} catch (CatalogException e) {
throw new ValidationException(exMsg, e);
}
}
```
> 2. Do we have plan to offer a default CatalogStore if user didn’t config
this?
Yes, the in-memory catalogStore will be used as the default CatalogStore
even if the user has not configured one
Best,
Feng
On Tue, Jun 6, 2023 at 8:28 PM Leonard Xu wrote:
> Hi, Feng
>
> Thanks for driving this FLIP, very impressive feature that users want,
> I’ve some quick questions here.
>
> 1.Unification SQL:
> The snapshot concept exists both in Batch mode and Streaming
> mode, could we consider a unified proposal? I think users won’t another
> SQL syntax named
> Time travel for Streaming mode.
>
> 2.Semantics:
> Flink supports TIMESTAMP and TIMESTAMP_LTZ types, to get a long
> timestamp value (getTable(ObjectPath tablePath, long timestamp)) we need
> two information i.e. a TIMESTAMP value and current session timezone, how
> we deal the value with current proposed SQL syntax.
>
> 3. Is it enough using sinlge timestamp to track a snapshot(version) of
> external table? Some external systems may use timestamp value to mark a
> version, but others may use version number、file position、log offset.
>
> Best,
> Leonard
>
>
>
> > On Jun 5, 2023, at 3:28 PM, Yun Tang wrote:
> >
> > Hi Feng,
> >
> > I think this FLIP would provide one important feature to unify the
> stream-SQL and batch-SQL when we backfill the historical data in batch mode.
> >
> > For the "Syntax" session, I think you could add descriptions of how to
> align backfill time travel with querying the latest data. And I think you
> should also update the "Discussion thread" in the original FLIP.
> >
> > Moreover, I have a question about getting the table schema from the
> catalog. I'm not sure whether the Catalog#getTable(tablePath, timestamp)
> will be called only once. If we have a backfill query between 2023-05-29
> and 2023-06-04 in the past week, and the table schema changed on
> 2023-06-01, will the query below detect the schema changes during backfill
> the whole week?
> >
> > SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP BETWEEN
> '2023-05-29 00:00:00' AND '2023-06-05 00:00:00'
> >
> > Best
> > Yun Tang
> >
> >
> >
> > From: Shammon FY
> > Sent: Thursday, June 1, 2023 17:57
> > To: dev@flink.apache.org
> > Subject: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
> >
> > Hi Feng,
> >
> > I have one minor comment about the public interface `Optional
> > getSnapshot()` in the `CatalogTable`.
> >
> > As we can get tables from the new method `Catalog.getTable(ObjectPath
> > tablePath, long timestamp)`, I think the returned `CatalogBaseTable` will
> > have the information of timestamp. Flink or connector such as
> > iceberg/paimon can create sources from the `CatalogBaseTable` directly
> > without the need to get the snapshot ID from
> `CatalogTable.getSnapshot()`.
> > What do you think of it?
> >
> > Best,
> > Shammon FY
> >
> >
> > On Thu, Jun 1, 2023 at 7:22 AM Jing Ge
> wrote:
> >
> >> Hi Feng,
> >>
> >> Thanks for the proposal! Very interesting feature. Would you like to
> update
> >> your thoughts described in your previous email about why
> SupportsTimeTravel
> >> has been rejected into the FLIP? This will help readers understand the
> >> context (in the future).
> >>
> >> Since we always directly add overload methods into Catalog according to
>
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi, Feng Thanks for driving this FLIP, very impressive feature that users want, I’ve some quick questions here. 1.Unification SQL: The snapshot concept exists both in Batch mode and Streaming mode, could we consider a unified proposal? I think users won’t another SQL syntax named Time travel for Streaming mode. 2.Semantics: Flink supports TIMESTAMP and TIMESTAMP_LTZ types, to get a long timestamp value (getTable(ObjectPath tablePath, long timestamp)) we need two information i.e. a TIMESTAMP value and current session timezone, how we deal the value with current proposed SQL syntax. 3. Is it enough using sinlge timestamp to track a snapshot(version) of external table? Some external systems may use timestamp value to mark a version, but others may use version number、file position、log offset. Best, Leonard > On Jun 5, 2023, at 3:28 PM, Yun Tang wrote: > > Hi Feng, > > I think this FLIP would provide one important feature to unify the stream-SQL > and batch-SQL when we backfill the historical data in batch mode. > > For the "Syntax" session, I think you could add descriptions of how to align > backfill time travel with querying the latest data. And I think you should > also update the "Discussion thread" in the original FLIP. > > Moreover, I have a question about getting the table schema from the catalog. > I'm not sure whether the Catalog#getTable(tablePath, timestamp) will be > called only once. If we have a backfill query between 2023-05-29 and > 2023-06-04 in the past week, and the table schema changed on 2023-06-01, will > the query below detect the schema changes during backfill the whole week? > > SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP BETWEEN '2023-05-29 > 00:00:00' AND '2023-06-05 00:00:00' > > Best > Yun Tang > > > > From: Shammon FY > Sent: Thursday, June 1, 2023 17:57 > To: dev@flink.apache.org > Subject: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > Hi Feng, > > I have one minor comment about the public interface `Optional > getSnapshot()` in the `CatalogTable`. > > As we can get tables from the new method `Catalog.getTable(ObjectPath > tablePath, long timestamp)`, I think the returned `CatalogBaseTable` will > have the information of timestamp. Flink or connector such as > iceberg/paimon can create sources from the `CatalogBaseTable` directly > without the need to get the snapshot ID from `CatalogTable.getSnapshot()`. > What do you think of it? > > Best, > Shammon FY > > > On Thu, Jun 1, 2023 at 7:22 AM Jing Ge wrote: > >> Hi Feng, >> >> Thanks for the proposal! Very interesting feature. Would you like to update >> your thoughts described in your previous email about why SupportsTimeTravel >> has been rejected into the FLIP? This will help readers understand the >> context (in the future). >> >> Since we always directly add overload methods into Catalog according to new >> requirements, which makes the interface bloated. Just out of curiosity, >> does it make sense to introduce some DSL design? Like >> Catalog.getTable(tablePath).on(timeStamp), >> Catalog.getTable(tablePath).current() for the most current version, and >> more room for further extension like timestamp range, etc. I haven't read >> all the source code yet and I'm not sure if it is possible. But a >> design like this will keep the Catalog API lean and the API/DSL will be >> self described and easier to use. >> >> Best regards, >> Jing >> >> >> On Wed, May 31, 2023 at 12:08 PM Krzysztof Chmielewski < >> krzysiek.chmielew...@gmail.com> wrote: >> >>> Ok after second though I'm retracting my previous statement about Catalog >>> changes you proposed. >>> I do see a benefit for Delta connector actually with this change and see >>> why this could be coupled with Catalog. >>> >>> Delta Connector SQL support, also ships a Delta Catalog implementation >> for >>> Flink. >>> For Delta Catalog, table schema information is fetched from underlying >>> _delta_log and not stored in metastore. For time travel we actually had a >>> problem, that if we would like to timetravel back to some old version, >>> where schema was slightly different, then we would have a conflict since >>> Catalog would return current schema and not how it was for version X. >>> >>> With your change, our Delta Catalog can actually fetch schema for >> version X >>> and send it to DeltaTableFactory. Currency, Catalog can fetch only >> current >>> version. What we wo
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi Feng, I think this FLIP would provide one important feature to unify the stream-SQL and batch-SQL when we backfill the historical data in batch mode. For the "Syntax" session, I think you could add descriptions of how to align backfill time travel with querying the latest data. And I think you should also update the "Discussion thread" in the original FLIP. Moreover, I have a question about getting the table schema from the catalog. I'm not sure whether the Catalog#getTable(tablePath, timestamp) will be called only once. If we have a backfill query between 2023-05-29 and 2023-06-04 in the past week, and the table schema changed on 2023-06-01, will the query below detect the schema changes during backfill the whole week? SELECT * FROM paimon_tb FOR SYSTEM_TIME AS OF TIMESTAMP BETWEEN '2023-05-29 00:00:00' AND '2023-06-05 00:00:00' Best Yun Tang From: Shammon FY Sent: Thursday, June 1, 2023 17:57 To: dev@flink.apache.org Subject: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode Hi Feng, I have one minor comment about the public interface `Optional getSnapshot()` in the `CatalogTable`. As we can get tables from the new method `Catalog.getTable(ObjectPath tablePath, long timestamp)`, I think the returned `CatalogBaseTable` will have the information of timestamp. Flink or connector such as iceberg/paimon can create sources from the `CatalogBaseTable` directly without the need to get the snapshot ID from `CatalogTable.getSnapshot()`. What do you think of it? Best, Shammon FY On Thu, Jun 1, 2023 at 7:22 AM Jing Ge wrote: > Hi Feng, > > Thanks for the proposal! Very interesting feature. Would you like to update > your thoughts described in your previous email about why SupportsTimeTravel > has been rejected into the FLIP? This will help readers understand the > context (in the future). > > Since we always directly add overload methods into Catalog according to new > requirements, which makes the interface bloated. Just out of curiosity, > does it make sense to introduce some DSL design? Like > Catalog.getTable(tablePath).on(timeStamp), > Catalog.getTable(tablePath).current() for the most current version, and > more room for further extension like timestamp range, etc. I haven't read > all the source code yet and I'm not sure if it is possible. But a > design like this will keep the Catalog API lean and the API/DSL will be > self described and easier to use. > > Best regards, > Jing > > > On Wed, May 31, 2023 at 12:08 PM Krzysztof Chmielewski < > krzysiek.chmielew...@gmail.com> wrote: > > > Ok after second though I'm retracting my previous statement about Catalog > > changes you proposed. > > I do see a benefit for Delta connector actually with this change and see > > why this could be coupled with Catalog. > > > > Delta Connector SQL support, also ships a Delta Catalog implementation > for > > Flink. > > For Delta Catalog, table schema information is fetched from underlying > > _delta_log and not stored in metastore. For time travel we actually had a > > problem, that if we would like to timetravel back to some old version, > > where schema was slightly different, then we would have a conflict since > > Catalog would return current schema and not how it was for version X. > > > > With your change, our Delta Catalog can actually fetch schema for > version X > > and send it to DeltaTableFactory. Currency, Catalog can fetch only > current > > version. What we would also need however is version (number/timestamp) > for > > this table passed to DynamicTableFactory so we could properly set Delta > > standalone library. > > > > Regards, > > Krzysztof > > > > śr., 31 maj 2023 o 10:37 Krzysztof Chmielewski < > > krzysiek.chmielew...@gmail.com> napisał(a): > > > > > Hi, > > > happy to see such a feature. > > > Small note from my end regarding Catalog changes. > > > > > > TL;DR > > > I don't think it is necessary to delegate this feature to the catalog. > I > > > think that since "timetravel" is per job/query property, its should not > > be > > > coupled with the Catalog or table definition. In my opinion this is > > > something that DynamicTableFactory only has to know about. I would > rather > > > see this feature as it is - SQL syntax enhancement but delegate clearly > > to > > > DynamicTableFactory. > > > > > > I've implemented timetravel feature for Delta Connector [1] using > > > current Flink API. > > > Docs are pending code review, but you can find them here [2] and > examples > > > are available here [3]
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/examples/flink-example/src/main/java/org/example/sql > > > > > > śr., 31 maj 2023 o 06:03 liu ron napisał(a): > > > > > >> Hi, Feng > > >> > > >> Thanks for driving this FLIP, Time travel is very useful for Flink > > >> integrate with data lake system. I have one question why the > > >> implementation > > >> of TimeTravel is delegated to Catalog? Assuming that we use Flink to > > query > > >> Hudi table with the time travel syntax, but we don't use the > > HudiCatalog, > > >> instead, we register the hudi table to InMemoryCatalog, can we > support > > >> time travel for Hudi table in this case? > > >> In contrast, I think time travel should bind to connector instead of > > >> Catalog, so the rejected alternative should be considered. > > >> > > >> Best, > > >> Ron > > >> > > >> yuxia 于2023年5月30日周二 09:40写道： > > >> > > >> > Hi, Feng. > > >> > Notice this FLIP only support batch mode for time travel. Would it > > also > > >> > make sense to support stream mode to a read a snapshot of the table > > as a > > >> > bounded stream? > > >> > > > >> > Best regards, > > >> > Yuxia > > >> > > > >> > - 原始邮件 - > > >> > 发件人: "Benchao Li" > > >> > 收件人: "dev" > > >> > 发送时间: 星期一, 2023年 5 月 29日 下午 6:04:53 > > >> > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > >> > > > >> > # Can Calcite support this syntax ` VERSION AS OF` ? > > >> > > > >> > This also depends on whether this is defined in standard or any > known > > >> > databases that have implemented this. If not, it would be hard to > push > > >> it > > >> > to Calcite. > > >> > > > >> > # getTable(ObjectPath object, long timestamp) > > >> > > > >> > Then we again come to the problem of "casting between timestamp and > > >> > numeric", which has been disabled in FLINK-21978[1]. If you're gonna > > use > > >> > this, then we need to clarify that problem first. > > >> > > > >> > [1] https://issues.apache.org/jira/browse/FLINK-21978 > > >> > > > >> > > > >> > Feng Jin 于2023年5月29日周一 15:57写道： > > >> > > > >> > > hi, thanks for your reply. > > >> > > > > >> > > @Benchao > > >> > > > did you consider the pushdown abilities compatible > > >> > > > > >> > > In the current design, the implementation of TimeTravel is > delegated > > >> to > > >> > > Catalog. We have added a function called getTable(ObjectPath > > >> tablePath, > > >> > > long timestamp) to obtain the corresponding CatalogBaseTable at a > > >> > specific > > >> > > time. Therefore, I think it will not have any impact on the > > original > > >> > > pushdown abilities. > > >> > > > > >> > > > > >> > > > I see there is a rejected design for adding > SupportsTimeTravel, > > >> but > > >> > I > > >> > > didn't see the alternative in the FLIP doc > > >> > > > > >> > > Sorry, the document description is not very clear. Regarding > > whether > > >> to > > >> > > support SupportTimeTravel, I have discussed it with yuxia. Since > we > > >> have > > >> > > already passed the corresponding time in getTable(ObjectPath, long > > >> > > timestamp) of Catalog, SupportTimeTravel may not be necessary. > > >> > > > > >> > > In getTable(ObjectPath object, long timestamp), we can obtain the > > >> schema > > >> > of > > >> > > the corresponding time point and put the SNAPSHOT that needs to be > > >> > consumed > > >> > > into options. > > >> > > > > >> > > > > >> > > @Shammon > > >> > > > Could we support this in Flink too? > > >> > > > > >> > > I personally think it's possible, but
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi Feng,
Thanks for the proposal! Very interesting feature. Would you like to update
your thoughts described in your previous email about why SupportsTimeTravel
has been rejected into the FLIP? This will help readers understand the
context (in the future).
Since we always directly add overload methods into Catalog according to new
requirements, which makes the interface bloated. Just out of curiosity,
does it make sense to introduce some DSL design? Like
Catalog.getTable(tablePath).on(timeStamp),
Catalog.getTable(tablePath).current() for the most current version, and
more room for further extension like timestamp range, etc. I haven't read
all the source code yet and I'm not sure if it is possible. But a
design like this will keep the Catalog API lean and the API/DSL will be
self described and easier to use.
Best regards,
Jing
On Wed, May 31, 2023 at 12:08 PM Krzysztof Chmielewski <
krzysiek.chmielew...@gmail.com> wrote:
> Ok after second though I'm retracting my previous statement about Catalog
> changes you proposed.
> I do see a benefit for Delta connector actually with this change and see
> why this could be coupled with Catalog.
>
> Delta Connector SQL support, also ships a Delta Catalog implementation for
> Flink.
> For Delta Catalog, table schema information is fetched from underlying
> _delta_log and not stored in metastore. For time travel we actually had a
> problem, that if we would like to timetravel back to some old version,
> where schema was slightly different, then we would have a conflict since
> Catalog would return current schema and not how it was for version X.
>
> With your change, our Delta Catalog can actually fetch schema for version X
> and send it to DeltaTableFactory. Currency, Catalog can fetch only current
> version. What we would also need however is version (number/timestamp) for
> this table passed to DynamicTableFactory so we could properly set Delta
> standalone library.
>
> Regards,
> Krzysztof
>
> śr., 31 maj 2023 o 10:37 Krzysztof Chmielewski <
> krzysiek.chmielew...@gmail.com> napisał(a):
>
> > Hi,
> > happy to see such a feature.
> > Small note from my end regarding Catalog changes.
> >
> > TL;DR
> > I don't think it is necessary to delegate this feature to the catalog. I
> > think that since "timetravel" is per job/query property, its should not
> be
> > coupled with the Catalog or table definition. In my opinion this is
> > something that DynamicTableFactory only has to know about. I would rather
> > see this feature as it is - SQL syntax enhancement but delegate clearly
> to
> > DynamicTableFactory.
> >
> > I've implemented timetravel feature for Delta Connector [1] using
> > current Flink API.
> > Docs are pending code review, but you can find them here [2] and examples
> > are available here [3]
> >
> > The timetravel feature that I've implemented is based on Flink Query
> > hints.
> > "SELECT * FROM sourceTable /*+ OPTIONS('versionAsOf' = '1') */"
> >
> > The " versionAsOf" (we also have 'timestampAsOf') parameter is handled
> not
> > by Catalog but by DyntamicTableFactory implementation for Delta
> connector.
> > The value of this property is passed to Delta standalone lib API that
> > returns table view for given version.
> >
> > I'm not sure how/if proposed change could benefit Delta connector
> > implementation for this feature.
> >
> > Thanks,
> > Krzysztof
> >
> > [1]
> >
> https://github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/flink
> > [2] https://github.com/kristoffSC/connectors/tree/FlinkSQL_PR_15-docs
> > [3]
> >
> https://github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/examples/flink-example/src/main/java/org/example/sql
> >
> > śr., 31 maj 2023 o 06:03 liu ron napisał(a):
> >
> >> Hi, Feng
> >>
> >> Thanks for driving this FLIP, Time travel is very useful for Flink
> >> integrate with data lake system. I have one question why the
> >> implementation
> >> of TimeTravel is delegated to Catalog? Assuming that we use Flink to
> query
> >> Hudi table with the time travel syntax, but we don't use the
> HudiCatalog,
> >> instead, we register the hudi table to InMemoryCatalog, can we support
> >> time travel for Hudi table in this case?
> >> In contrast, I think time travel should bind to connector instead of
> >> Catalog, so the rejected alternative should be considered.
> >>
> >> Best,
> >> Ron
> >>
> >> yuxia 于2023年5月30日周二 09:40写道：
> >>
> >> > Hi, Fe
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Ok after second though I'm retracting my previous statement about Catalog
changes you proposed.
I do see a benefit for Delta connector actually with this change and see
why this could be coupled with Catalog.
Delta Connector SQL support, also ships a Delta Catalog implementation for
Flink.
For Delta Catalog, table schema information is fetched from underlying
_delta_log and not stored in metastore. For time travel we actually had a
problem, that if we would like to timetravel back to some old version,
where schema was slightly different, then we would have a conflict since
Catalog would return current schema and not how it was for version X.
With your change, our Delta Catalog can actually fetch schema for version X
and send it to DeltaTableFactory. Currency, Catalog can fetch only current
version. What we would also need however is version (number/timestamp) for
this table passed to DynamicTableFactory so we could properly set Delta
standalone library.
Regards,
Krzysztof
śr., 31 maj 2023 o 10:37 Krzysztof Chmielewski <
krzysiek.chmielew...@gmail.com> napisał(a):
> Hi,
> happy to see such a feature.
> Small note from my end regarding Catalog changes.
>
> TL;DR
> I don't think it is necessary to delegate this feature to the catalog. I
> think that since "timetravel" is per job/query property, its should not be
> coupled with the Catalog or table definition. In my opinion this is
> something that DynamicTableFactory only has to know about. I would rather
> see this feature as it is - SQL syntax enhancement but delegate clearly to
> DynamicTableFactory.
>
> I've implemented timetravel feature for Delta Connector [1] using
> current Flink API.
> Docs are pending code review, but you can find them here [2] and examples
> are available here [3]
>
> The timetravel feature that I've implemented is based on Flink Query
> hints.
> "SELECT * FROM sourceTable /*+ OPTIONS('versionAsOf' = '1') */"
>
> The " versionAsOf" (we also have 'timestampAsOf') parameter is handled not
> by Catalog but by DyntamicTableFactory implementation for Delta connector.
> The value of this property is passed to Delta standalone lib API that
> returns table view for given version.
>
> I'm not sure how/if proposed change could benefit Delta connector
> implementation for this feature.
>
> Thanks,
> Krzysztof
>
> [1]
> https://github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/flink
> [2] https://github.com/kristoffSC/connectors/tree/FlinkSQL_PR_15-docs
> [3]
> https://github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/examples/flink-example/src/main/java/org/example/sql
>
> śr., 31 maj 2023 o 06:03 liu ron napisał(a):
>
>> Hi, Feng
>>
>> Thanks for driving this FLIP, Time travel is very useful for Flink
>> integrate with data lake system. I have one question why the
>> implementation
>> of TimeTravel is delegated to Catalog? Assuming that we use Flink to query
>> Hudi table with the time travel syntax, but we don't use the HudiCatalog,
>> instead, we register the hudi table to InMemoryCatalog, can we support
>> time travel for Hudi table in this case?
>> In contrast, I think time travel should bind to connector instead of
>> Catalog, so the rejected alternative should be considered.
>>
>> Best,
>> Ron
>>
>> yuxia 于2023年5月30日周二 09:40写道：
>>
>> > Hi, Feng.
>> > Notice this FLIP only support batch mode for time travel. Would it also
>> > make sense to support stream mode to a read a snapshot of the table as a
>> > bounded stream?
>> >
>> > Best regards,
>> > Yuxia
>> >
>> > - 原始邮件 -
>> > 发件人: "Benchao Li"
>> > 收件人: "dev"
>> > 发送时间: 星期一, 2023年 5 月 29日 下午 6:04:53
>> > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
>> >
>> > # Can Calcite support this syntax ` VERSION AS OF` ?
>> >
>> > This also depends on whether this is defined in standard or any known
>> > databases that have implemented this. If not, it would be hard to push
>> it
>> > to Calcite.
>> >
>> > # getTable(ObjectPath object, long timestamp)
>> >
>> > Then we again come to the problem of "casting between timestamp and
>> > numeric", which has been disabled in FLINK-21978[1]. If you're gonna use
>> > this, then we need to clarify that problem first.
>> >
>> > [1] https://issues.apache.org/jira/browse/FLINK-21978
>> >
>> >
>> > Feng Jin 于2023年5月29日周一 15:57写道：
>> >
>> > > hi, thanks for your reply.
>> > >
>> > &
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi,
happy to see such a feature.
Small note from my end regarding Catalog changes.
TL;DR
I don't think it is necessary to delegate this feature to the catalog. I
think that since "timetravel" is per job/query property, its should not be
coupled with the Catalog or table definition. In my opinion this is
something that DynamicTableFactory only has to know about. I would rather
see this feature as it is - SQL syntax enhancement but delegate clearly to
DynamicTableFactory.
I've implemented timetravel feature for Delta Connector [1] using current
Flink API.
Docs are pending code review, but you can find them here [2] and examples
are available here [3]
The timetravel feature that I've implemented is based on Flink Query hints.
"SELECT * FROM sourceTable /*+ OPTIONS('versionAsOf' = '1') */"
The " versionAsOf" (we also have 'timestampAsOf') parameter is handled not
by Catalog but by DyntamicTableFactory implementation for Delta connector.
The value of this property is passed to Delta standalone lib API that
returns table view for given version.
I'm not sure how/if proposed change could benefit Delta connector
implementation for this feature.
Thanks,
Krzysztof
[1]
https://github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/flink
[2] https://github.com/kristoffSC/connectors/tree/FlinkSQL_PR_15-docs
[3]
https://github.com/delta-io/connectors/tree/flink_table_catalog_feature_branch/examples/flink-example/src/main/java/org/example/sql
śr., 31 maj 2023 o 06:03 liu ron napisał(a):
> Hi, Feng
>
> Thanks for driving this FLIP, Time travel is very useful for Flink
> integrate with data lake system. I have one question why the implementation
> of TimeTravel is delegated to Catalog? Assuming that we use Flink to query
> Hudi table with the time travel syntax, but we don't use the HudiCatalog,
> instead, we register the hudi table to InMemoryCatalog, can we support
> time travel for Hudi table in this case?
> In contrast, I think time travel should bind to connector instead of
> Catalog, so the rejected alternative should be considered.
>
> Best,
> Ron
>
> yuxia 于2023年5月30日周二 09:40写道：
>
> > Hi, Feng.
> > Notice this FLIP only support batch mode for time travel. Would it also
> > make sense to support stream mode to a read a snapshot of the table as a
> > bounded stream?
> >
> > Best regards,
> > Yuxia
> >
> > ----- 原始邮件 -
> > 发件人: "Benchao Li"
> > 收件人: "dev"
> > 发送时间: 星期一, 2023年 5 月 29日 下午 6:04:53
> > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
> >
> > # Can Calcite support this syntax ` VERSION AS OF` ?
> >
> > This also depends on whether this is defined in standard or any known
> > databases that have implemented this. If not, it would be hard to push it
> > to Calcite.
> >
> > # getTable(ObjectPath object, long timestamp)
> >
> > Then we again come to the problem of "casting between timestamp and
> > numeric", which has been disabled in FLINK-21978[1]. If you're gonna use
> > this, then we need to clarify that problem first.
> >
> > [1] https://issues.apache.org/jira/browse/FLINK-21978
> >
> >
> > Feng Jin 于2023年5月29日周一 15:57写道：
> >
> > > hi, thanks for your reply.
> > >
> > > @Benchao
> > > > did you consider the pushdown abilities compatible
> > >
> > > In the current design, the implementation of TimeTravel is delegated to
> > > Catalog. We have added a function called getTable(ObjectPath tablePath,
> > > long timestamp) to obtain the corresponding CatalogBaseTable at a
> > specific
> > > time. Therefore, I think it will not have any impact on the original
> > > pushdown abilities.
> > >
> > >
> > > > I see there is a rejected design for adding SupportsTimeTravel,
> but
> > I
> > > didn't see the alternative in the FLIP doc
> > >
> > > Sorry, the document description is not very clear. Regarding whether
> to
> > > support SupportTimeTravel, I have discussed it with yuxia. Since we
> have
> > > already passed the corresponding time in getTable(ObjectPath, long
> > > timestamp) of Catalog, SupportTimeTravel may not be necessary.
> > >
> > > In getTable(ObjectPath object, long timestamp), we can obtain the
> schema
> > of
> > > the corresponding time point and put the SNAPSHOT that needs to be
> > consumed
> > > into options.
> > >
> > >
> > > @Shammon
> > > > Could we support this in Flink too?
> > >
> > > I personally think it's possible, but limited by Calc
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi, Feng Thanks for driving this FLIP, Time travel is very useful for Flink integrate with data lake system. I have one question why the implementation of TimeTravel is delegated to Catalog? Assuming that we use Flink to query Hudi table with the time travel syntax, but we don't use the HudiCatalog, instead, we register the hudi table to InMemoryCatalog, can we support time travel for Hudi table in this case? In contrast, I think time travel should bind to connector instead of Catalog, so the rejected alternative should be considered. Best, Ron yuxia 于2023年5月30日周二 09:40写道： > Hi, Feng. > Notice this FLIP only support batch mode for time travel. Would it also > make sense to support stream mode to a read a snapshot of the table as a > bounded stream? > > Best regards, > Yuxia > > - 原始邮件 - > 发件人: "Benchao Li" > 收件人: "dev" > 发送时间: 星期一, 2023年 5 月 29日 下午 6:04:53 > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > # Can Calcite support this syntax ` VERSION AS OF` ? > > This also depends on whether this is defined in standard or any known > databases that have implemented this. If not, it would be hard to push it > to Calcite. > > # getTable(ObjectPath object, long timestamp) > > Then we again come to the problem of "casting between timestamp and > numeric", which has been disabled in FLINK-21978[1]. If you're gonna use > this, then we need to clarify that problem first. > > [1] https://issues.apache.org/jira/browse/FLINK-21978 > > > Feng Jin 于2023年5月29日周一 15:57写道： > > > hi, thanks for your reply. > > > > @Benchao > > > did you consider the pushdown abilities compatible > > > > In the current design, the implementation of TimeTravel is delegated to > > Catalog. We have added a function called getTable(ObjectPath tablePath, > > long timestamp) to obtain the corresponding CatalogBaseTable at a > specific > > time. Therefore, I think it will not have any impact on the original > > pushdown abilities. > > > > > > > I see there is a rejected design for adding SupportsTimeTravel, but > I > > didn't see the alternative in the FLIP doc > > > > Sorry, the document description is not very clear. Regarding whether to > > support SupportTimeTravel, I have discussed it with yuxia. Since we have > > already passed the corresponding time in getTable(ObjectPath, long > > timestamp) of Catalog, SupportTimeTravel may not be necessary. > > > > In getTable(ObjectPath object, long timestamp), we can obtain the schema > of > > the corresponding time point and put the SNAPSHOT that needs to be > consumed > > into options. > > > > > > @Shammon > > > Could we support this in Flink too? > > > > I personally think it's possible, but limited by Calcite's syntax > > restrictions. I believe we should first support this syntax in Calcite. > > Currently, I think it may not be easy to support this syntax in Flink's > > parser. @Benchao, what do you think? Can Calcite support this syntax > > ` VERSION AS OF` ? > > > > > > Best, > > Feng. > > > > > > On Fri, May 26, 2023 at 2:55 PM Shammon FY wrote: > > > > > Thanks Feng, the feature of time travel sounds great! > > > > > > In addition to SYSTEM_TIME, lake houses such as paimon and iceberg > > support > > > snapshot or version. For example, users can query snapshot 1 for paimon > > by > > > the following statement > > > SELECT * FROM t VERSION AS OF 1 > > > > > > Could we support this in Flink too? > > > > > > Best, > > > Shammon FY > > > > > > On Fri, May 26, 2023 at 1:20 PM Benchao Li > wrote: > > > > > > > Regarding the implementation, did you consider the pushdown abilities > > > > compatible, e.g., projection pushdown, filter pushdown, partition > > > pushdown. > > > > Since `Snapshot` is not handled much in existing rules, I have a > > concern > > > > about this. Of course, it depends on your implementation detail, what > > is > > > > important is that we'd better add some cross tests for these. > > > > > > > > Regarding the interface exposed to Connector, I see there is a > rejected > > > > design for adding SupportsTimeTravel, but I didn't see the > alternative > > in > > > > the FLIP doc. IMO, this is an important thing we need to clarify > > because > > > we > > > > need to know whether the Connector supports this, and what > > > column/me
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi, Feng. Notice this FLIP only support batch mode for time travel. Would it also make sense to support stream mode to a read a snapshot of the table as a bounded stream? Best regards, Yuxia - 原始邮件 - 发件人: "Benchao Li" 收件人: "dev" 发送时间: 星期一, 2023年 5 月 29日 下午 6:04:53 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode # Can Calcite support this syntax ` VERSION AS OF` ? This also depends on whether this is defined in standard or any known databases that have implemented this. If not, it would be hard to push it to Calcite. # getTable(ObjectPath object, long timestamp) Then we again come to the problem of "casting between timestamp and numeric", which has been disabled in FLINK-21978[1]. If you're gonna use this, then we need to clarify that problem first. [1] https://issues.apache.org/jira/browse/FLINK-21978 Feng Jin 于2023年5月29日周一 15:57写道： > hi, thanks for your reply. > > @Benchao > > did you consider the pushdown abilities compatible > > In the current design, the implementation of TimeTravel is delegated to > Catalog. We have added a function called getTable(ObjectPath tablePath, > long timestamp) to obtain the corresponding CatalogBaseTable at a specific > time. Therefore, I think it will not have any impact on the original > pushdown abilities. > > > > I see there is a rejected design for adding SupportsTimeTravel, but I > didn't see the alternative in the FLIP doc > > Sorry, the document description is not very clear. Regarding whether to > support SupportTimeTravel, I have discussed it with yuxia. Since we have > already passed the corresponding time in getTable(ObjectPath, long > timestamp) of Catalog, SupportTimeTravel may not be necessary. > > In getTable(ObjectPath object, long timestamp), we can obtain the schema of > the corresponding time point and put the SNAPSHOT that needs to be consumed > into options. > > > @Shammon > > Could we support this in Flink too? > > I personally think it's possible, but limited by Calcite's syntax > restrictions. I believe we should first support this syntax in Calcite. > Currently, I think it may not be easy to support this syntax in Flink's > parser. @Benchao, what do you think? Can Calcite support this syntax > ` VERSION AS OF` ? > > > Best, > Feng. > > > On Fri, May 26, 2023 at 2:55 PM Shammon FY wrote: > > > Thanks Feng, the feature of time travel sounds great! > > > > In addition to SYSTEM_TIME, lake houses such as paimon and iceberg > support > > snapshot or version. For example, users can query snapshot 1 for paimon > by > > the following statement > > SELECT * FROM t VERSION AS OF 1 > > > > Could we support this in Flink too? > > > > Best, > > Shammon FY > > > > On Fri, May 26, 2023 at 1:20 PM Benchao Li wrote: > > > > > Regarding the implementation, did you consider the pushdown abilities > > > compatible, e.g., projection pushdown, filter pushdown, partition > > pushdown. > > > Since `Snapshot` is not handled much in existing rules, I have a > concern > > > about this. Of course, it depends on your implementation detail, what > is > > > important is that we'd better add some cross tests for these. > > > > > > Regarding the interface exposed to Connector, I see there is a rejected > > > design for adding SupportsTimeTravel, but I didn't see the alternative > in > > > the FLIP doc. IMO, this is an important thing we need to clarify > because > > we > > > need to know whether the Connector supports this, and what > > column/metadata > > > corresponds to 'system_time'. > > > > > > Feng Jin 于2023年5月25日周四 22:50写道： > > > > > > > Thanks for your reply > > > > > > > > @Timo @BenChao @yuxia > > > > > > > > Sorry for the mistake, Currently , calcite only supports `FOR > > > SYSTEM_TIME > > > > AS OF ` syntax. We can only support `FOR SYSTEM_TIME AS OF` . I've > > > > updated the syntax part of the FLIP. > > > > > > > > > > > > @Timo > > > > > > > > > We will convert it to TIMESTAMP_LTZ? > > > > > > > > Yes, I think we need to convert TIMESTAMP to TIMESTAMP_LTZ and then > > > convert > > > > it into a long value. > > > > > > > > > How do we want to query the most recent version of a table > > > > > > > > I think we can use `AS OF CURRENT_TIMESTAMP` ，But it does cause > > > > inconsistency with the real-time concept. > > > > However, from my pe
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
by default. > > > > > > > > > > > > > > > > Best, > > > > Feng > > > > > > > > > > > > On Thu, May 25, 2023 at 7:47 PM yuxia > > > wrote: > > > > > > > > > Thanks Feng for bringing this up. It'll be great to introduce time > > > travel > > > > > to Flink to have a better integration with external data soruces. > > > > > > > > > > I also share same concern about the syntax. > > > > > I see in the part of `Whether to support other syntax > > implementations` > > > in > > > > > this FLIP, seems the syntax in Calcite should be `FOR SYSTEM_TIME > AS > > > OF`, > > > > > right? > > > > > But the the syntax part in this FLIP, it seems to be `AS OF > > TIMESTAMP` > > > > > instead of `FOR SYSTEM_TIME AS OF`. Is it just a mistake or by > > design? > > > > > > > > > > > > > > > Best regards, > > > > > Yuxia > > > > > > > > > > - 原始邮件 - > > > > > 发件人: "Benchao Li" > > > > > 收件人: "dev" > > > > > 发送时间: 星期四, 2023年 5 月 25日 下午 7:27:17 > > > > > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > > > > > > > > > Thanks Feng, it's exciting to have this ability. > > > > > > > > > > Regarding the syntax section, are you proposing `AS OF` instead of > > `FOR > > > > > SYSTEM AS OF` to do this? I know `FOR SYSTEM AS OF` is in the SQL > > > > standard > > > > > and has been supported in some database vendors such as SQL Server. > > > About > > > > > `AS OF`, is it in the standard or any database vendor supports > this, > > if > > > > > yes, I think it's worth to add this support to Calcite, and I would > > > give > > > > a > > > > > hand in Calcite side. Otherwise, I think we'd better to use `FOR > > SYSTEM > > > > AS > > > > > OF`. > > > > > > > > > > Timo Walther 于2023年5月25日周四 19:02写道： > > > > > > > > > > > Also: How do we want to query the most recent version of a table? > > > > > > > > > > > > `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the > docs > > > > both > > > > > > the type is TIMESTAMP_LTZ and what is even more concerning is the > > it > > > > > > actually is evalated row-based: > > > > > > > > > > > > > Returns the current SQL timestamp in the local time zone, the > > > return > > > > > > type is TIMESTAMP_LTZ(3). It is evaluated for each record in > > > streaming > > > > > > mode. But in batch mode, it is evaluated once as the query starts > > and > > > > > > uses the same result for every row. > > > > > > > > > > > > This could make it difficult to explain in a join scenario of > > > multiple > > > > > > snapshotted tables. > > > > > > > > > > > > Regards, > > > > > > Timo > > > > > > > > > > > > > > > > > > On 25.05.23 12:29, Timo Walther wrote: > > > > > > > Hi Feng, > > > > > > > > > > > > > > thanks for proposing this FLIP. It makes a lot of sense to > > finally > > > > > > > support querying tables at a specific point in time or > hopefully > > > also > > > > > > > ranges soon. Following time-versioned tables. > > > > > > > > > > > > > > Here is some feedback from my side: > > > > > > > > > > > > > > 1. Syntax > > > > > > > > > > > > > > Can you elaborate a bit on the Calcite restrictions? > > > > > > > > > > > > > > Does Calcite currently support `AS OF` syntax for this but not > > `FOR > > > > > > > SYSTEM_TIME AS OF`? > > > > > > > > > > > > > > It would be great to support `AS OF` also for time-versioned > > joins > > > > and > > > > > > > have a unified and short syntax. > > > > > > > > > > > > > > Once a fix is merg
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
hi, thanks for your reply. @Benchao > did you consider the pushdown abilities compatible In the current design, the implementation of TimeTravel is delegated to Catalog. We have added a function called getTable(ObjectPath tablePath, long timestamp) to obtain the corresponding CatalogBaseTable at a specific time. Therefore, I think it will not have any impact on the original pushdown abilities. > I see there is a rejected design for adding SupportsTimeTravel, but I didn't see the alternative in the FLIP doc Sorry, the document description is not very clear. Regarding whether to support SupportTimeTravel, I have discussed it with yuxia. Since we have already passed the corresponding time in getTable(ObjectPath, long timestamp) of Catalog, SupportTimeTravel may not be necessary. In getTable(ObjectPath object, long timestamp), we can obtain the schema of the corresponding time point and put the SNAPSHOT that needs to be consumed into options. @Shammon > Could we support this in Flink too? I personally think it's possible, but limited by Calcite's syntax restrictions. I believe we should first support this syntax in Calcite. Currently, I think it may not be easy to support this syntax in Flink's parser. @Benchao, what do you think? Can Calcite support this syntax ` VERSION AS OF` ? Best, Feng. On Fri, May 26, 2023 at 2:55 PM Shammon FY wrote: > Thanks Feng, the feature of time travel sounds great! > > In addition to SYSTEM_TIME, lake houses such as paimon and iceberg support > snapshot or version. For example, users can query snapshot 1 for paimon by > the following statement > SELECT * FROM t VERSION AS OF 1 > > Could we support this in Flink too? > > Best, > Shammon FY > > On Fri, May 26, 2023 at 1:20 PM Benchao Li wrote: > > > Regarding the implementation, did you consider the pushdown abilities > > compatible, e.g., projection pushdown, filter pushdown, partition > pushdown. > > Since `Snapshot` is not handled much in existing rules, I have a concern > > about this. Of course, it depends on your implementation detail, what is > > important is that we'd better add some cross tests for these. > > > > Regarding the interface exposed to Connector, I see there is a rejected > > design for adding SupportsTimeTravel, but I didn't see the alternative in > > the FLIP doc. IMO, this is an important thing we need to clarify because > we > > need to know whether the Connector supports this, and what > column/metadata > > corresponds to 'system_time'. > > > > Feng Jin 于2023年5月25日周四 22:50写道： > > > > > Thanks for your reply > > > > > > @Timo @BenChao @yuxia > > > > > > Sorry for the mistake, Currently , calcite only supports `FOR > > SYSTEM_TIME > > > AS OF ` syntax. We can only support `FOR SYSTEM_TIME AS OF` . I've > > > updated the syntax part of the FLIP. > > > > > > > > > @Timo > > > > > > > We will convert it to TIMESTAMP_LTZ? > > > > > > Yes, I think we need to convert TIMESTAMP to TIMESTAMP_LTZ and then > > convert > > > it into a long value. > > > > > > > How do we want to query the most recent version of a table > > > > > > I think we can use `AS OF CURRENT_TIMESTAMP` ，But it does cause > > > inconsistency with the real-time concept. > > > However, from my personal understanding, the scope of `AS OF > > > CURRENT_TIMESTAMP` is the table itself, not the table record. So, I > > think > > > using CURRENT_TIMESTAMP should also be reasonable?. > > > Additionally, if no version is specified, the latest version should be > > used > > > by default. > > > > > > > > > > > > Best, > > > Feng > > > > > > > > > On Thu, May 25, 2023 at 7:47 PM yuxia > > wrote: > > > > > > > Thanks Feng for bringing this up. It'll be great to introduce time > > travel > > > > to Flink to have a better integration with external data soruces. > > > > > > > > I also share same concern about the syntax. > > > > I see in the part of `Whether to support other syntax > implementations` > > in > > > > this FLIP, seems the syntax in Calcite should be `FOR SYSTEM_TIME AS > > OF`, > > > > right? > > > > But the the syntax part in this FLIP, it seems to be `AS OF > TIMESTAMP` > > > > instead of `FOR SYSTEM_TIME AS OF`. Is it just a mistake or by > design? > > > > > > > > > > > > Best regards, > > > > Yuxia > > > > > > > > - 原始邮件 - &
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Thanks Feng, the feature of time travel sounds great! In addition to SYSTEM_TIME, lake houses such as paimon and iceberg support snapshot or version. For example, users can query snapshot 1 for paimon by the following statement SELECT * FROM t VERSION AS OF 1 Could we support this in Flink too? Best, Shammon FY On Fri, May 26, 2023 at 1:20 PM Benchao Li wrote: > Regarding the implementation, did you consider the pushdown abilities > compatible, e.g., projection pushdown, filter pushdown, partition pushdown. > Since `Snapshot` is not handled much in existing rules, I have a concern > about this. Of course, it depends on your implementation detail, what is > important is that we'd better add some cross tests for these. > > Regarding the interface exposed to Connector, I see there is a rejected > design for adding SupportsTimeTravel, but I didn't see the alternative in > the FLIP doc. IMO, this is an important thing we need to clarify because we > need to know whether the Connector supports this, and what column/metadata > corresponds to 'system_time'. > > Feng Jin 于2023年5月25日周四 22:50写道： > > > Thanks for your reply > > > > @Timo @BenChao @yuxia > > > > Sorry for the mistake, Currently , calcite only supports `FOR > SYSTEM_TIME > > AS OF ` syntax. We can only support `FOR SYSTEM_TIME AS OF` . I've > > updated the syntax part of the FLIP. > > > > > > @Timo > > > > > We will convert it to TIMESTAMP_LTZ? > > > > Yes, I think we need to convert TIMESTAMP to TIMESTAMP_LTZ and then > convert > > it into a long value. > > > > > How do we want to query the most recent version of a table > > > > I think we can use `AS OF CURRENT_TIMESTAMP` ，But it does cause > > inconsistency with the real-time concept. > > However, from my personal understanding, the scope of `AS OF > > CURRENT_TIMESTAMP` is the table itself, not the table record. So, I > think > > using CURRENT_TIMESTAMP should also be reasonable?. > > Additionally, if no version is specified, the latest version should be > used > > by default. > > > > > > > > Best, > > Feng > > > > > > On Thu, May 25, 2023 at 7:47 PM yuxia > wrote: > > > > > Thanks Feng for bringing this up. It'll be great to introduce time > travel > > > to Flink to have a better integration with external data soruces. > > > > > > I also share same concern about the syntax. > > > I see in the part of `Whether to support other syntax implementations` > in > > > this FLIP, seems the syntax in Calcite should be `FOR SYSTEM_TIME AS > OF`, > > > right? > > > But the the syntax part in this FLIP, it seems to be `AS OF TIMESTAMP` > > > instead of `FOR SYSTEM_TIME AS OF`. Is it just a mistake or by design? > > > > > > > > > Best regards, > > > Yuxia > > > > > > - 原始邮件 - > > > 发件人: "Benchao Li" > > > 收件人: "dev" > > > 发送时间: 星期四, 2023年 5 月 25日 下午 7:27:17 > > > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > > > > > Thanks Feng, it's exciting to have this ability. > > > > > > Regarding the syntax section, are you proposing `AS OF` instead of `FOR > > > SYSTEM AS OF` to do this? I know `FOR SYSTEM AS OF` is in the SQL > > standard > > > and has been supported in some database vendors such as SQL Server. > About > > > `AS OF`, is it in the standard or any database vendor supports this, if > > > yes, I think it's worth to add this support to Calcite, and I would > give > > a > > > hand in Calcite side. Otherwise, I think we'd better to use `FOR SYSTEM > > AS > > > OF`. > > > > > > Timo Walther 于2023年5月25日周四 19:02写道： > > > > > > > Also: How do we want to query the most recent version of a table? > > > > > > > > `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the docs > > both > > > > the type is TIMESTAMP_LTZ and what is even more concerning is the it > > > > actually is evalated row-based: > > > > > > > > > Returns the current SQL timestamp in the local time zone, the > return > > > > type is TIMESTAMP_LTZ(3). It is evaluated for each record in > streaming > > > > mode. But in batch mode, it is evaluated once as the query starts and > > > > uses the same result for every row. > > > > > > > > This could make it difficult to explain in a join scenario of > multiple > > > &
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Regarding the implementation, did you consider the pushdown abilities compatible, e.g., projection pushdown, filter pushdown, partition pushdown. Since `Snapshot` is not handled much in existing rules, I have a concern about this. Of course, it depends on your implementation detail, what is important is that we'd better add some cross tests for these. Regarding the interface exposed to Connector, I see there is a rejected design for adding SupportsTimeTravel, but I didn't see the alternative in the FLIP doc. IMO, this is an important thing we need to clarify because we need to know whether the Connector supports this, and what column/metadata corresponds to 'system_time'. Feng Jin 于2023年5月25日周四 22:50写道： > Thanks for your reply > > @Timo @BenChao @yuxia > > Sorry for the mistake, Currently , calcite only supports `FOR SYSTEM_TIME > AS OF ` syntax. We can only support `FOR SYSTEM_TIME AS OF` . I've > updated the syntax part of the FLIP. > > > @Timo > > > We will convert it to TIMESTAMP_LTZ? > > Yes, I think we need to convert TIMESTAMP to TIMESTAMP_LTZ and then convert > it into a long value. > > > How do we want to query the most recent version of a table > > I think we can use `AS OF CURRENT_TIMESTAMP` ，But it does cause > inconsistency with the real-time concept. > However, from my personal understanding, the scope of `AS OF > CURRENT_TIMESTAMP` is the table itself, not the table record. So, I think > using CURRENT_TIMESTAMP should also be reasonable?. > Additionally, if no version is specified, the latest version should be used > by default. > > > > Best, > Feng > > > On Thu, May 25, 2023 at 7:47 PM yuxia wrote: > > > Thanks Feng for bringing this up. It'll be great to introduce time travel > > to Flink to have a better integration with external data soruces. > > > > I also share same concern about the syntax. > > I see in the part of `Whether to support other syntax implementations` in > > this FLIP, seems the syntax in Calcite should be `FOR SYSTEM_TIME AS OF`, > > right? > > But the the syntax part in this FLIP, it seems to be `AS OF TIMESTAMP` > > instead of `FOR SYSTEM_TIME AS OF`. Is it just a mistake or by design? > > > > > > Best regards, > > Yuxia > > > > - 原始邮件 - > > 发件人: "Benchao Li" > > 收件人: "dev" > > 发送时间: 星期四, 2023年 5 月 25日 下午 7:27:17 > > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > > > Thanks Feng, it's exciting to have this ability. > > > > Regarding the syntax section, are you proposing `AS OF` instead of `FOR > > SYSTEM AS OF` to do this? I know `FOR SYSTEM AS OF` is in the SQL > standard > > and has been supported in some database vendors such as SQL Server. About > > `AS OF`, is it in the standard or any database vendor supports this, if > > yes, I think it's worth to add this support to Calcite, and I would give > a > > hand in Calcite side. Otherwise, I think we'd better to use `FOR SYSTEM > AS > > OF`. > > > > Timo Walther 于2023年5月25日周四 19:02写道： > > > > > Also: How do we want to query the most recent version of a table? > > > > > > `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the docs > both > > > the type is TIMESTAMP_LTZ and what is even more concerning is the it > > > actually is evalated row-based: > > > > > > > Returns the current SQL timestamp in the local time zone, the return > > > type is TIMESTAMP_LTZ(3). It is evaluated for each record in streaming > > > mode. But in batch mode, it is evaluated once as the query starts and > > > uses the same result for every row. > > > > > > This could make it difficult to explain in a join scenario of multiple > > > snapshotted tables. > > > > > > Regards, > > > Timo > > > > > > > > > On 25.05.23 12:29, Timo Walther wrote: > > > > Hi Feng, > > > > > > > > thanks for proposing this FLIP. It makes a lot of sense to finally > > > > support querying tables at a specific point in time or hopefully also > > > > ranges soon. Following time-versioned tables. > > > > > > > > Here is some feedback from my side: > > > > > > > > 1. Syntax > > > > > > > > Can you elaborate a bit on the Calcite restrictions? > > > > > > > > Does Calcite currently support `AS OF` syntax for this but not `FOR > > > > SYSTEM_TIME AS OF`? > > > > > > > > It would be great to support `AS OF` also for time-ver
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Thanks for your reply @Timo @BenChao @yuxia Sorry for the mistake, Currently , calcite only supports `FOR SYSTEM_TIME AS OF ` syntax. We can only support `FOR SYSTEM_TIME AS OF` . I've updated the syntax part of the FLIP. @Timo > We will convert it to TIMESTAMP_LTZ? Yes, I think we need to convert TIMESTAMP to TIMESTAMP_LTZ and then convert it into a long value. > How do we want to query the most recent version of a table I think we can use `AS OF CURRENT_TIMESTAMP` ，But it does cause inconsistency with the real-time concept. However, from my personal understanding, the scope of `AS OF CURRENT_TIMESTAMP` is the table itself, not the table record. So, I think using CURRENT_TIMESTAMP should also be reasonable?. Additionally, if no version is specified, the latest version should be used by default. Best, Feng On Thu, May 25, 2023 at 7:47 PM yuxia wrote: > Thanks Feng for bringing this up. It'll be great to introduce time travel > to Flink to have a better integration with external data soruces. > > I also share same concern about the syntax. > I see in the part of `Whether to support other syntax implementations` in > this FLIP, seems the syntax in Calcite should be `FOR SYSTEM_TIME AS OF`, > right? > But the the syntax part in this FLIP, it seems to be `AS OF TIMESTAMP` > instead of `FOR SYSTEM_TIME AS OF`. Is it just a mistake or by design? > > > Best regards, > Yuxia > > - 原始邮件 - > 发件人: "Benchao Li" > 收件人: "dev" > 发送时间: 星期四, 2023年 5 月 25日 下午 7:27:17 > 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode > > Thanks Feng, it's exciting to have this ability. > > Regarding the syntax section, are you proposing `AS OF` instead of `FOR > SYSTEM AS OF` to do this? I know `FOR SYSTEM AS OF` is in the SQL standard > and has been supported in some database vendors such as SQL Server. About > `AS OF`, is it in the standard or any database vendor supports this, if > yes, I think it's worth to add this support to Calcite, and I would give a > hand in Calcite side. Otherwise, I think we'd better to use `FOR SYSTEM AS > OF`. > > Timo Walther 于2023年5月25日周四 19:02写道： > > > Also: How do we want to query the most recent version of a table? > > > > `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the docs both > > the type is TIMESTAMP_LTZ and what is even more concerning is the it > > actually is evalated row-based: > > > > > Returns the current SQL timestamp in the local time zone, the return > > type is TIMESTAMP_LTZ(3). It is evaluated for each record in streaming > > mode. But in batch mode, it is evaluated once as the query starts and > > uses the same result for every row. > > > > This could make it difficult to explain in a join scenario of multiple > > snapshotted tables. > > > > Regards, > > Timo > > > > > > On 25.05.23 12:29, Timo Walther wrote: > > > Hi Feng, > > > > > > thanks for proposing this FLIP. It makes a lot of sense to finally > > > support querying tables at a specific point in time or hopefully also > > > ranges soon. Following time-versioned tables. > > > > > > Here is some feedback from my side: > > > > > > 1. Syntax > > > > > > Can you elaborate a bit on the Calcite restrictions? > > > > > > Does Calcite currently support `AS OF` syntax for this but not `FOR > > > SYSTEM_TIME AS OF`? > > > > > > It would be great to support `AS OF` also for time-versioned joins and > > > have a unified and short syntax. > > > > > > Once a fix is merged in Calcite for this, we can make this available in > > > Flink earlier by copying the corresponding classes until the next > > > Calcite upgrade is performed. > > > > > > 2. Semantics > > > > > > How do we interpret the timestamp? In Flink we have 2 timestamp types > > > (TIMESTAMP and TIMESTAMP_LTZ). If users specify AS OF TIMESTAMP > > > '2023-04-27 00:00:00', in which timezone will the timestamp be? We will > > > convert it to TIMESTAMP_LTZ? > > > > > > We definely need to clarify this because the past has shown that > > > daylight saving times make our lives hard. > > > > > > Thanks, > > > Timo > > > > > > On 25.05.23 10:57, Feng Jin wrote: > > >> Hi, everyone. > > >> > > >> I’d like to start a discussion about FLIP-308: Support Time Travel In > > >> Batch > > >> Mode [1] > > >> > > >> > > >> Time travel is a SQL syntax used to query historica
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Thanks Feng for bringing this up. It'll be great to introduce time travel to Flink to have a better integration with external data soruces. I also share same concern about the syntax. I see in the part of `Whether to support other syntax implementations` in this FLIP, seems the syntax in Calcite should be `FOR SYSTEM_TIME AS OF`, right? But the the syntax part in this FLIP, it seems to be `AS OF TIMESTAMP` instead of `FOR SYSTEM_TIME AS OF`. Is it just a mistake or by design? Best regards, Yuxia - 原始邮件 - 发件人: "Benchao Li" 收件人: "dev" 发送时间: 星期四, 2023年 5 月 25日 下午 7:27:17 主题: Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode Thanks Feng, it's exciting to have this ability. Regarding the syntax section, are you proposing `AS OF` instead of `FOR SYSTEM AS OF` to do this? I know `FOR SYSTEM AS OF` is in the SQL standard and has been supported in some database vendors such as SQL Server. About `AS OF`, is it in the standard or any database vendor supports this, if yes, I think it's worth to add this support to Calcite, and I would give a hand in Calcite side. Otherwise, I think we'd better to use `FOR SYSTEM AS OF`. Timo Walther 于2023年5月25日周四 19:02写道： > Also: How do we want to query the most recent version of a table? > > `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the docs both > the type is TIMESTAMP_LTZ and what is even more concerning is the it > actually is evalated row-based: > > > Returns the current SQL timestamp in the local time zone, the return > type is TIMESTAMP_LTZ(3). It is evaluated for each record in streaming > mode. But in batch mode, it is evaluated once as the query starts and > uses the same result for every row. > > This could make it difficult to explain in a join scenario of multiple > snapshotted tables. > > Regards, > Timo > > > On 25.05.23 12:29, Timo Walther wrote: > > Hi Feng, > > > > thanks for proposing this FLIP. It makes a lot of sense to finally > > support querying tables at a specific point in time or hopefully also > > ranges soon. Following time-versioned tables. > > > > Here is some feedback from my side: > > > > 1. Syntax > > > > Can you elaborate a bit on the Calcite restrictions? > > > > Does Calcite currently support `AS OF` syntax for this but not `FOR > > SYSTEM_TIME AS OF`? > > > > It would be great to support `AS OF` also for time-versioned joins and > > have a unified and short syntax. > > > > Once a fix is merged in Calcite for this, we can make this available in > > Flink earlier by copying the corresponding classes until the next > > Calcite upgrade is performed. > > > > 2. Semantics > > > > How do we interpret the timestamp? In Flink we have 2 timestamp types > > (TIMESTAMP and TIMESTAMP_LTZ). If users specify AS OF TIMESTAMP > > '2023-04-27 00:00:00', in which timezone will the timestamp be? We will > > convert it to TIMESTAMP_LTZ? > > > > We definely need to clarify this because the past has shown that > > daylight saving times make our lives hard. > > > > Thanks, > > Timo > > > > On 25.05.23 10:57, Feng Jin wrote: > >> Hi, everyone. > >> > >> I’d like to start a discussion about FLIP-308: Support Time Travel In > >> Batch > >> Mode [1] > >> > >> > >> Time travel is a SQL syntax used to query historical versions of data. > It > >> allows users to specify a point in time and retrieve the data and > >> schema of > >> a table as it appeared at that time. With time travel, users can easily > >> analyze and compare historical versions of data. > >> > >> > >> With the widespread use of data lake systems such as Paimon, Iceberg, > and > >> Hudi, time travel can provide more convenience for users' data analysis. > >> > >> > >> Looking forward to your opinions, any suggestions are welcomed. > >> > >> > >> > >> 1. > >> > https://cwiki.apache.org/confluence/display/FLINK/FLIP-308%3A+Support+Time+Travel+In+Batch+Mode > >> > >> > >> > >> Best. > >> > >> Feng > >> > > > > -- Best, Benchao Li
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Thanks Feng, it's exciting to have this ability. Regarding the syntax section, are you proposing `AS OF` instead of `FOR SYSTEM AS OF` to do this? I know `FOR SYSTEM AS OF` is in the SQL standard and has been supported in some database vendors such as SQL Server. About `AS OF`, is it in the standard or any database vendor supports this, if yes, I think it's worth to add this support to Calcite, and I would give a hand in Calcite side. Otherwise, I think we'd better to use `FOR SYSTEM AS OF`. Timo Walther 于2023年5月25日周四 19:02写道： > Also: How do we want to query the most recent version of a table? > > `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the docs both > the type is TIMESTAMP_LTZ and what is even more concerning is the it > actually is evalated row-based: > > > Returns the current SQL timestamp in the local time zone, the return > type is TIMESTAMP_LTZ(3). It is evaluated for each record in streaming > mode. But in batch mode, it is evaluated once as the query starts and > uses the same result for every row. > > This could make it difficult to explain in a join scenario of multiple > snapshotted tables. > > Regards, > Timo > > > On 25.05.23 12:29, Timo Walther wrote: > > Hi Feng, > > > > thanks for proposing this FLIP. It makes a lot of sense to finally > > support querying tables at a specific point in time or hopefully also > > ranges soon. Following time-versioned tables. > > > > Here is some feedback from my side: > > > > 1. Syntax > > > > Can you elaborate a bit on the Calcite restrictions? > > > > Does Calcite currently support `AS OF` syntax for this but not `FOR > > SYSTEM_TIME AS OF`? > > > > It would be great to support `AS OF` also for time-versioned joins and > > have a unified and short syntax. > > > > Once a fix is merged in Calcite for this, we can make this available in > > Flink earlier by copying the corresponding classes until the next > > Calcite upgrade is performed. > > > > 2. Semantics > > > > How do we interpret the timestamp? In Flink we have 2 timestamp types > > (TIMESTAMP and TIMESTAMP_LTZ). If users specify AS OF TIMESTAMP > > '2023-04-27 00:00:00', in which timezone will the timestamp be? We will > > convert it to TIMESTAMP_LTZ? > > > > We definely need to clarify this because the past has shown that > > daylight saving times make our lives hard. > > > > Thanks, > > Timo > > > > On 25.05.23 10:57, Feng Jin wrote: > >> Hi, everyone. > >> > >> I’d like to start a discussion about FLIP-308: Support Time Travel In > >> Batch > >> Mode [1] > >> > >> > >> Time travel is a SQL syntax used to query historical versions of data. > It > >> allows users to specify a point in time and retrieve the data and > >> schema of > >> a table as it appeared at that time. With time travel, users can easily > >> analyze and compare historical versions of data. > >> > >> > >> With the widespread use of data lake systems such as Paimon, Iceberg, > and > >> Hudi, time travel can provide more convenience for users' data analysis. > >> > >> > >> Looking forward to your opinions, any suggestions are welcomed. > >> > >> > >> > >> 1. > >> > https://cwiki.apache.org/confluence/display/FLINK/FLIP-308%3A+Support+Time+Travel+In+Batch+Mode > >> > >> > >> > >> Best. > >> > >> Feng > >> > > > > -- Best, Benchao Li
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Also: How do we want to query the most recent version of a table? `AS OF CURRENT_TIMESTAMP` would be ideal, but according to the docs both the type is TIMESTAMP_LTZ and what is even more concerning is the it actually is evalated row-based: > Returns the current SQL timestamp in the local time zone, the return type is TIMESTAMP_LTZ(3). It is evaluated for each record in streaming mode. But in batch mode, it is evaluated once as the query starts and uses the same result for every row. This could make it difficult to explain in a join scenario of multiple snapshotted tables. Regards, Timo On 25.05.23 12:29, Timo Walther wrote: Hi Feng, thanks for proposing this FLIP. It makes a lot of sense to finally support querying tables at a specific point in time or hopefully also ranges soon. Following time-versioned tables. Here is some feedback from my side: 1. Syntax Can you elaborate a bit on the Calcite restrictions? Does Calcite currently support `AS OF` syntax for this but not `FOR SYSTEM_TIME AS OF`? It would be great to support `AS OF` also for time-versioned joins and have a unified and short syntax. Once a fix is merged in Calcite for this, we can make this available in Flink earlier by copying the corresponding classes until the next Calcite upgrade is performed. 2. Semantics How do we interpret the timestamp? In Flink we have 2 timestamp types (TIMESTAMP and TIMESTAMP_LTZ). If users specify AS OF TIMESTAMP '2023-04-27 00:00:00', in which timezone will the timestamp be? We will convert it to TIMESTAMP_LTZ? We definely need to clarify this because the past has shown that daylight saving times make our lives hard. Thanks, Timo On 25.05.23 10:57, Feng Jin wrote: Hi, everyone. I’d like to start a discussion about FLIP-308: Support Time Travel In Batch Mode [1] Time travel is a SQL syntax used to query historical versions of data. It allows users to specify a point in time and retrieve the data and schema of a table as it appeared at that time. With time travel, users can easily analyze and compare historical versions of data. With the widespread use of data lake systems such as Paimon, Iceberg, and Hudi, time travel can provide more convenience for users' data analysis. Looking forward to your opinions, any suggestions are welcomed. 1. https://cwiki.apache.org/confluence/display/FLINK/FLIP-308%3A+Support+Time+Travel+In+Batch+Mode Best. Feng
Re: [DISCUSS] FLIP-308: Support Time Travel In Batch Mode
Hi Feng, thanks for proposing this FLIP. It makes a lot of sense to finally support querying tables at a specific point in time or hopefully also ranges soon. Following time-versioned tables. Here is some feedback from my side: 1. Syntax Can you elaborate a bit on the Calcite restrictions? Does Calcite currently support `AS OF` syntax for this but not `FOR SYSTEM_TIME AS OF`? It would be great to support `AS OF` also for time-versioned joins and have a unified and short syntax. Once a fix is merged in Calcite for this, we can make this available in Flink earlier by copying the corresponding classes until the next Calcite upgrade is performed. 2. Semantics How do we interpret the timestamp? In Flink we have 2 timestamp types (TIMESTAMP and TIMESTAMP_LTZ). If users specify AS OF TIMESTAMP '2023-04-27 00:00:00', in which timezone will the timestamp be? We will convert it to TIMESTAMP_LTZ? We definely need to clarify this because the past has shown that daylight saving times make our lives hard. Thanks, Timo On 25.05.23 10:57, Feng Jin wrote: Hi, everyone. I’d like to start a discussion about FLIP-308: Support Time Travel In Batch Mode [1] Time travel is a SQL syntax used to query historical versions of data. It allows users to specify a point in time and retrieve the data and schema of a table as it appeared at that time. With time travel, users can easily analyze and compare historical versions of data. With the widespread use of data lake systems such as Paimon, Iceberg, and Hudi, time travel can provide more convenience for users' data analysis. Looking forward to your opinions, any suggestions are welcomed. 1. https://cwiki.apache.org/confluence/display/FLINK/FLIP-308%3A+Support+Time+Travel+In+Batch+Mode Best. Feng
