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https://issues.apache.org/jira/browse/BEAM-10896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17214845#comment-17214845
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Beam JIRA Bot commented on BEAM-10896:
--------------------------------------
This issue is assigned but has not received an update in 30 days so it has been
labeled "stale-assigned". If you are still working on the issue, please give an
update and remove the label. If you are no longer working on the issue, please
unassign so someone else may work on it. In 7 days the issue will be
automatically unassigned.
> Support UNNEST an array of structs
> ----------------------------------
>
> Key: BEAM-10896
> URL: https://issues.apache.org/jira/browse/BEAM-10896
> Project: Beam
> Issue Type: New Feature
> Components: dsl-sql-zetasql
> Reporter: Robin Qiu
> Assignee: Robin Qiu
> Priority: P2
> Labels: stale-assigned
>
> Currently UNNEST an array of structs does not work properly in Beam ZetaSQL:
>
> e.g. SELECT p.some_field FROM table, UNNEST(table.array_of_structs) AS p
>
> Execution of such queries will crash with error in ProjectScanConverter:
> Exception in thread "main" java.lang.AssertionError: Field ordinal 1 is
> invalid for type 'RecordType(VARCHAR id)'Exception in thread "main"
> java.lang.AssertionError: Field ordinal 1 is invalid for type
> 'RecordType(VARCHAR id)' at
> org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexBuilder.makeFieldAccess(RexBuilder.java:197)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertResolvedStructFieldAccessInternal(ExpressionConverter.java:881)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertResolvedStructFieldAccess(ExpressionConverter.java:871)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertRexNodeFromResolvedExpr(ExpressionConverter.java:309)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertResolvedStructFieldAccess(ExpressionConverter.java:869)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertRexNodeFromResolvedExpr(ExpressionConverter.java:309)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertResolvedStructFieldAccess(ExpressionConverter.java:869)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertRexNodeFromResolvedExpr(ExpressionConverter.java:309)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.convertRexNodeFromComputedColumnWithFieldList(ExpressionConverter.java:368)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ExpressionConverter.retrieveRexNode(ExpressionConverter.java:196)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ProjectScanConverter.convert(ProjectScanConverter.java:45)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.ProjectScanConverter.convert(ProjectScanConverter.java:29)
> at
> org.apache.beam.sdk.extensions.sql.zetasql.translation.QueryStatementConverter.convertNode(QueryStatementConverter.java:99)
>
> The root cause is that Calcite 1.20.0 Uncollect will "unwrap" the struct/row
> in an array being unnested:
> [https://github.com/apache/calcite/blob/calcite-1.20.0/core/src/main/java/org/apache/calcite/rel/core/Uncollect.java#L146-L152]
>
> The Calcite Uncollect API has a change in 1.23.0 that could provide us a way
> to bypass this "unwrapping":
> https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/core/Uncollect.java#L171-L172
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