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Posted to issues@calcite.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2019/09/29 10:28:00 UTC
[jira] [Updated] (CALCITE-3379) Support expand atom expression in
table to relational node conversion
[ https://issues.apache.org/jira/browse/CALCITE-3379?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
ASF GitHub Bot updated CALCITE-3379:
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Labels: pull-request-available (was: )
> Support expand atom expression in table to relational node conversion
> ---------------------------------------------------------------------
>
> Key: CALCITE-3379
> URL: https://issues.apache.org/jira/browse/CALCITE-3379
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.21.0
> Reporter: Danny Chen
> Assignee: Danny Chen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.22.0
>
>
> Now there are 2 ways to convert a RelOptTable to LogicalTableScan:
> 1. One way is tp open the Config#sConvertTableAccess[1] flag and the SqlToRelConverter would invoke the #toRel method which transforms the table to a node returned by the user(Usually a table scan).
> 2. Another way it to use the LogicalTableScan rule, this rule would invoke RelOptTable#toRel and wrap the returned node with a LogicalTableScan.
>
> The different between 1 and 2 is that, 2 happens in the planning rule but 1 happens in sql-to-rel conversion, 1 also supports to expand the table columns based on the defined default values expressions, see InitializerExpressionFactory#newColumnDefaultValue.
>
> The problem with the InitializerExpressionFactory#newColumnDefaultValue is that it use InitializerContext#convertExpression to convert a SqlNode, if the SqlNode is not validated, we always got a RexCall with SqlUnresolvedFunction. We should give the user change to validate their SqlNode or even we can support pure string expressions because they can be used to persist.
>
> Another problem with #toRel is that after the expressions applied as a projection, use has no change to apply any other rel nodes if they want, we can actually support this, the same way as we support the column expressions.
>
> [1]https://github.com/apache/calcite/blob/2dc97e6723e1b5bf762540f87ffffb5cd1a848a1/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java#L5605
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