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https://issues.apache.org/jira/browse/CALCITE-5711?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-5711:
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Labels: pull-request-available (was: )
> Implement the SINGLE_VALUE aggregation in PostgreSQL Dialect
> ------------------------------------------------------------
>
> Key: CALCITE-5711
> URL: https://issues.apache.org/jira/browse/CALCITE-5711
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.34.0
> Reporter: xiong duan
> Assignee: xiong duan
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.35.0
>
>
> When we use the SQL including the scalar query, converting this SQL Rel to
> PostgreSQL will include the SINGLE_VALUE aggregation function(PostgreSQL
> can't handle it) in the dialect SQL.
> Input SQL:
> {code:java}
> select "product_class_id" as c
> from "product" where "brand_name" = (select "product_name" from "product")
> {code}
> PostgreSQL Dialect now generates SQL:
> {code:java}
> SELECT \"product\".\"product_class_id\" AS \"C\"
> FROM \"foodmart\".\"product\"
> LEFT JOIN (SELECT SINGLE_VALUE(\"product_name\") AS \"$f0\"
> FROM \"foodmart\".\"product\") AS \"t0\" ON TRUE
> WHERE \"product\".\"brand_name\" = \"t0\".\"$f0\" {code}
> PostgreSQL Dialect will generate SQL:
> {code:java}
> SELECT "product"."product_class_id" AS "C"
> FROM "foodmart"."product"
> LEFT JOIN (SELECT CASE COUNT(*) WHEN 0 THEN NULL WHEN 1 THEN
> MIN("product_name") ELSE (SELECT CAST(NULL AS VARCHAR(60))
> UNION ALL
> SELECT CAST(NULL AS VARCHAR(60))) END AS "$f0"
> FROM "foodmart"."product") AS "t0" ON TRUE
> WHERE "product"."brand_name" = "t0"."$f0" {code}
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