I tried your patch and I think you are right, there is some missing feature for RelStructuredTypeFlattener, When the field you want to project is a struct but not at top level, an error throws.
I tried to close the flattening and it works well, originally the RelStructuredTypeFlattener was designed to extract nested fields so that the work like de-correlation is much easier, but it also makes the plan changed and hard to maintain, it is not updated frequently, if possible, close the flattening. Best, Danny Chan 在 2020年6月19日 +0800 AM4:39，Slim Bouguerra <bs...@apache.org>，写道： > @Danny it is attached to the case CALCITE-4065 > > https://jira.apache.org/jira/secure/attachment/13005815/13005815_test_cases_CALCITE-4065.patch > Thanks > > On Thu, Jun 18, 2020 at 12:29 AM Danny Chan <yuzhao....@gmail.com> wrote: > > > What diff, I didn’t see that ~ > > > > Best, > > Danny Chan > > 在 2020年6月16日 +0800 PM11:52，Slim Bouguerra <slim.bougue...@gmail.com>，写道： > > > Hi Danny I have run some test yesterday with > > RelToSqlConverterStructsTest I have attached the diff, let me know what you > > think > > > > > > > > > > On Tue, Jun 16, 2020 at 2:22 AM Danny Chan <yuzhao....@gmail.com> > > wrote: > > > > > Take SqlToRelConverterTest#testAliasUnnestArrayPlanWithSingleColumn > > for an example, you should make every record type with > > StructKind.PEEK_FIELDS, so that nested record type can be also accessed > > with DOT. > > > > > > > > > > Best, > > > > > Danny Chan > > > > > 在 2020年6月16日 +0800 PM12:50，Slim Bouguerra <bs...@apache.org>，写道： > > > > > > Hi Danny, > > > > > > Thanks for the suggestion, but that did not solve the problem, > > still > > > > > > getting the same exception, Not sure If I am missing something ? > > Do you > > > > > > have an example of this usage ? > > > > > > Again the goal here is to select a Row for a Row as an example > > this is the > > > > > > column type sketch > > > > > > outerRow(address_kind, address_inner_row(ZipCode, StreetNum,....)) > > > > > > SELECT outerRow.address_inner_row FROM table. > > > > > > > > > > > > FYI select outerRow.address_kind works because it is a scalar and > > after > > > > > > adding your suggestion I see that select address_kind from table. > > > > > > > > > > > > On Mon, Jun 15, 2020 at 7:21 PM Danny Chan <yuzhao....@gmail.com> > > wrote: > > > > > > > > > > > > > Hi, when you create a structure type, you should choose > > > > > > > StructKind.PEEK_FIELDS instead, which let you to access the > > nested fields > > > > > > > with DOT, i.e. “a.b.c”. > > > > > > > > > > > > > > Best, > > > > > > > Danny Chan > > > > > > > 在 2020年6月16日 +0800 AM4:21，Slim Bouguerra <bs...@apache.org>，写道： > > > > > > > > I am using this thread since the question seems related. > > > > > > > > As of now I can not say a way to project a nested record (FYI > > scalar > > > > > > > > works). https://jira.apache.org/jira/browse/CALCITE-4065 > > > > > > > > @Igor any idea if this can be done without major work on the > > > > > > > > SqlRelToRelConverter ? > > > > > > > > Also I am thinking about turning off the flatten stage but not > > sure this > > > > > > > is > > > > > > > > going to happen (seems like a pandora box kind of flag where > > you do not > > > > > > > > know what to expect) > > > > > > > > > > > > > > > > On Thu, Oct 24, 2019 at 3:53 AM Igor Guzenko < > > ihor.huzenko....@gmail.com > > > > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > Hello Naveen, > > > > > > > > > > > > > > > > > > 1. If I understand correctly, then yes you can extract > > nested fields > > > > > > > from > > > > > > > > > struct type. The syntax depends on StructKind value for your > > data type, > > > > > > > > > for example for FULLY_QUALIFIED struct you should first > > > > > > > > > make alias for your table and then request nested field like, > > > > > > > > > table_alias.struct_column.nested_field. In rel tree such > > expressions > > > > > > > are > > > > > > > > > presented as RexCall with SqlItemOperator operator. > > > > > > > > > 2. Yes, this ability was implemented in CALCITE-3138 [1]. It > > builds > > > > > > > call to > > > > > > > > > ROW type constructor function on top of flattened tree for > > necessary > > > > > > > > > columns. > > > > > > > > > 3. Yes, examples of such functions are ROW(...), > > ANY_VALUE(...) etc. > > > > > > > > > > > > > > > > > > In current implementation of flattener invocation of ROW > > constructor > > > > > > > > > function is done despite of null handling same issue exists > > for some > > > > > > > > > aggregate function flattening, like COUNT(struct_column). > > > > > > > > > Proper null handling is real pain for flattener, original > > idea was to > > > > > > > > > handle special null indicator for each flattened struct, but > > in > > > > > > > practice I > > > > > > > > > recognized that it's really hard to deal with flattened > > fields indices > > > > > > > when > > > > > > > > > related methods are called from very different points, so > > for now the > > > > > > > > > problem remains unsolved. > > > > > > > > > If you can't avoid dealing with null values in your struct > > columns you > > > > > > > > > could try to avoid invocation to > > SqlToRelConverter.flattenTypes(...) > > > > > > > and > > > > > > > > > check whether final plan acceptable for you. As far as I know > > > > > > > > > there is no reading material for given topic, you can > > investigate > > > > > > > source > > > > > > > > > code by debugging RelStructuredTypeFlattener and reading > > some related > > > > > > > plans > > > > > > > > > in SqlToRelConverterTest.java and SqlToRelConverterTest.xml. > > > > > > > > > > > > > > > > > > [1] https://issues.apache.org/jira/browse/CALCITE-3138 > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > Igor > > > > > > > > > > > > > > > > > > On Thu, Oct 24, 2019 at 12:57 PM Naveen Kumar > > > > > > > > > <naveenkuma...@flipkart.com.invalid> wrote: > > > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > > > I work at Flipkart, we are using Calcite in our streaming > > platform. > > > > > > > In > > > > > > > > > most > > > > > > > > > > of our use cases, input data is nested. I understand > > Calcite flattens > > > > > > > > > > structs in scan and references fields positionally. > > > > > > > > > > > > > > > > > > > > I had a few questions on handling nested data - > > > > > > > > > > > > > > > > > > > > 1. Can RelNode DAG work with nested data (instead of > > flattened > > > > > > > fields) > > > > > > > > > > by referencing fields through their nested structure eg, > > > > > > > > > > data.order.orderId > > > > > > > > > > 2. In the current flattened behavior, can output of a > > query be a > > > > > > > > > struct. > > > > > > > > > > Eg if *orderId, orderData.timestamp, orderData.category* > > are output > > > > > > > of > > > > > > > > > > select query, can I declaratively organise output to below > > json > > > > > > > > > > structure - > > > > > > > > > > 1. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > *{ "orderId": "order1", "orderData": { "timestamp": > > 1571904384814, > > > > > > > > > > "category": "shoes" } }* > > > > > > > > > > 3. Can output of a UDF be struct type > > > > > > > > > > > > > > > > > > > > Please point me to any reading material or example that > > would help > > > > > > > with > > > > > > > > > > these questions. > > > > > > > > > > > > > > > > > > > > Regards, > > > > > > > > > > Naveen > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > *-----------------------------------------------------------------------------------------* > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > *This email and any files transmitted with it are > > confidential and > > > > > > > > > > intended solely for the use of the individual or entity to > > whom they > > > > > > > are > > > > > > > > > > addressed. If you have received this email in error, > > please notify > > > > > > > the > > > > > > > > > > system manager. 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