[jira] [Assigned] (SPARK-4502) Spark SQL reads unneccesary nested fields from Parquet
[
https://issues.apache.org/jira/browse/SPARK-4502?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Xiao Li reassigned SPARK-4502:
--
Assignee: Michael Allman
> Spark SQL reads unneccesary nested fields from Parquet
> --
>
> Key: SPARK-4502
> URL: https://issues.apache.org/jira/browse/SPARK-4502
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 1.1.0
>Reporter: Liwen Sun
>Assignee: Michael Allman
>Priority: Critical
> Fix For: 2.4.0
>
>
> When reading a field of a nested column from Parquet, SparkSQL reads and
> assemble all the fields of that nested column. This is unnecessary, as
> Parquet supports fine-grained field reads out of a nested column. This may
> degrades the performance significantly when a nested column has many fields.
> For example, I loaded json tweets data into SparkSQL and ran the following
> query:
> {{SELECT User.contributors_enabled from Tweets;}}
> User is a nested structure that has 38 primitive fields (for Tweets schema,
> see: https://dev.twitter.com/overview/api/tweets), here is the log message:
> {{14/11/19 16:36:49 INFO InternalParquetRecordReader: Assembled and processed
> 385779 records from 38 columns in 3976 ms: 97.02691 rec/ms, 3687.0227
> cell/ms}}
> For comparison, I also ran:
> {{SELECT User FROM Tweets;}}
> And here is the log message:
> {{14/11/19 16:45:40 INFO InternalParquetRecordReader: Assembled and processed
> 385779 records from 38 columns in 9461 ms: 40.77571 rec/ms, 1549.477 cell/ms}}
> So both queries load 38 columns from Parquet, while the first query only
> needs 1 column. I also measured the bytes read within Parquet. In these two
> cases, the same number of bytes (99365194 bytes) were read.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
-
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Assigned] (SPARK-4502) Spark SQL reads unneccesary nested fields from Parquet
[
https://issues.apache.org/jira/browse/SPARK-4502?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Apache Spark reassigned SPARK-4502:
---
Assignee: (was: Apache Spark)
> Spark SQL reads unneccesary nested fields from Parquet
> --
>
> Key: SPARK-4502
> URL: https://issues.apache.org/jira/browse/SPARK-4502
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 1.1.0
>Reporter: Liwen Sun
>Priority: Critical
>
> When reading a field of a nested column from Parquet, SparkSQL reads and
> assemble all the fields of that nested column. This is unnecessary, as
> Parquet supports fine-grained field reads out of a nested column. This may
> degrades the performance significantly when a nested column has many fields.
> For example, I loaded json tweets data into SparkSQL and ran the following
> query:
> {{SELECT User.contributors_enabled from Tweets;}}
> User is a nested structure that has 38 primitive fields (for Tweets schema,
> see: https://dev.twitter.com/overview/api/tweets), here is the log message:
> {{14/11/19 16:36:49 INFO InternalParquetRecordReader: Assembled and processed
> 385779 records from 38 columns in 3976 ms: 97.02691 rec/ms, 3687.0227
> cell/ms}}
> For comparison, I also ran:
> {{SELECT User FROM Tweets;}}
> And here is the log message:
> {{14/11/19 16:45:40 INFO InternalParquetRecordReader: Assembled and processed
> 385779 records from 38 columns in 9461 ms: 40.77571 rec/ms, 1549.477 cell/ms}}
> So both queries load 38 columns from Parquet, while the first query only
> needs 1 column. I also measured the bytes read within Parquet. In these two
> cases, the same number of bytes (99365194 bytes) were read.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
-
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Assigned] (SPARK-4502) Spark SQL reads unneccesary nested fields from Parquet
[
https://issues.apache.org/jira/browse/SPARK-4502?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Apache Spark reassigned SPARK-4502:
---
Assignee: Apache Spark
> Spark SQL reads unneccesary nested fields from Parquet
> --
>
> Key: SPARK-4502
> URL: https://issues.apache.org/jira/browse/SPARK-4502
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 1.1.0
>Reporter: Liwen Sun
>Assignee: Apache Spark
>Priority: Critical
>
> When reading a field of a nested column from Parquet, SparkSQL reads and
> assemble all the fields of that nested column. This is unnecessary, as
> Parquet supports fine-grained field reads out of a nested column. This may
> degrades the performance significantly when a nested column has many fields.
> For example, I loaded json tweets data into SparkSQL and ran the following
> query:
> {{SELECT User.contributors_enabled from Tweets;}}
> User is a nested structure that has 38 primitive fields (for Tweets schema,
> see: https://dev.twitter.com/overview/api/tweets), here is the log message:
> {{14/11/19 16:36:49 INFO InternalParquetRecordReader: Assembled and processed
> 385779 records from 38 columns in 3976 ms: 97.02691 rec/ms, 3687.0227
> cell/ms}}
> For comparison, I also ran:
> {{SELECT User FROM Tweets;}}
> And here is the log message:
> {{14/11/19 16:45:40 INFO InternalParquetRecordReader: Assembled and processed
> 385779 records from 38 columns in 9461 ms: 40.77571 rec/ms, 1549.477 cell/ms}}
> So both queries load 38 columns from Parquet, while the first query only
> needs 1 column. I also measured the bytes read within Parquet. In these two
> cases, the same number of bytes (99365194 bytes) were read.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
-
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
