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https://issues.apache.org/jira/browse/CALCITE-6355?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-6355:
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Labels: pull-request-available (was: )
> RelToSqlConverter[ORDER BY] generates an incorrect order by when NULLS LAST
> is used in non-projected field
> ----------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-6355
> URL: https://issues.apache.org/jira/browse/CALCITE-6355
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.36.0
> Reporter: Bruno Volpato
> Priority: Minor
> Labels: pull-request-available
>
>
> We are using RelToSqlConverter, and seeing issues with it generating invalid
> queries when using _DESC NULLS LAST,_ specifically.
>
> For example, this test query:
>
> {code:java}
> select "product_id"
> from "product"
> where "net_weight" is not null
> group by "product_id"
> order by MAX("net_weight") desc {code}
> Gets resolved correctly, with a subquery, to:
>
> {code:java}
> SELECT "product_id"
> FROM (SELECT "product_id", MAX("net_weight") AS "EXPR$1"
> FROM "foodmart"."product"
> WHERE "net_weight" IS NOT NULL
> GROUP BY "product_id"
> ORDER BY 2 DESC) AS "t3" {code}
>
>
> However, if I specify `desc nulls last`:
>
> {code:java}
> select "product_id"
> from "product"
> where "net_weight" is not null
> group by "product_id"
> order by MAX("net_weight") desc nulls last {code}
> It creates an invalid query (order by 2, but only one field was projected):
>
>
> {code:java}
> SELECT "product_id"
> FROM "foodmart"."product"
> WHERE "net_weight" IS NOT NULL
> GROUP BY "product_id"
> ORDER BY 2 DESC NULLS LAST {code}
>
>
>
> Trying to troubleshoot it, it appears that without the `NULLS LAST`, we have
> the following instance:
>
> {code:java}
> SqlBasicCall -> SqlNumericLiteral {code}
>
>
> But when including it, it gets wrapped in another call:
>
> {code:java}
> SqlBasicCall -> SqlBasicCall -> SqlNumericLiteral {code}
>
>
> So the [hasSortByOrdinal
> method|https://github.com/apache/calcite/blob/main/core/src/main/java/org/apache/calcite/rel/rel2sql/SqlImplementor.java#L1938C21-L1958]
> ends up returning {_}false{_}, which causes `needNewSubQuery` to incorrectly
> report _false_ too.
>
> It appears that the best way to deal with this is by using a recursion to
> find numeric literals - but let me know if there are better ideas.
>
> I plan to take a stab at this since I got enough context.
>
>
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