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https://issues.apache.org/jira/browse/CALCITE-7642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18093779#comment-18093779
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zzwqqq commented on CALCITE-7642:
---------------------------------
[~jensen] Thanks for checking. You are right that the generated SQL is valid in
PostgreSQL because quoted identifiers are case-sensitive there.
I should have described the issue more precisely. This is not a PostgreSQL
runtime error. In the example, I used a PostgreSQL dialect with
case-sensitivity disabled, but RelToSqlConverter still produced output names
`id` and `ID`.
Row type field names may be uniquified using the type factory's type system,
but SQL output names should follow the target dialect's case-sensitivity. I
think the second output name should be uniquified as `ID0` for this dialect.
> RelToSqlConverter may generate duplicate output column names for
> case-insensitive dialects
> ------------------------------------------------------------------------------------------
>
> Key: CALCITE-7642
> URL: https://issues.apache.org/jira/browse/CALCITE-7642
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: zzwqqq
> Assignee: zzwqqq
> Priority: Major
> Labels: pull-request-available
>
> RelToSqlConverter can emit output column names that are distinct in a row
> type but not distinct for the target dialect.
> Reproducer:
> Use a case-insensitive PostgreSQL dialect:
> {code:java}
> new PostgresqlSqlDialect(
> PostgresqlSqlDialect.DEFAULT_CONTEXT.withCaseSensitive(false)){code}
> Input SQL:
> {code:sql}
> SELECT *
> FROM (VALUES (1)) AS "t" ("id")
> JOIN (VALUES (1)) AS "t0" ("ID") ON TRUE
>
> {code}
> Current output:
> {code:java}
> SELECT "t"."id", "t0"."ID"
> FROM (VALUES (1)) AS "t" ("id"),
> (VALUES (1)) AS "t0" ("ID"){code}
> The output column names are "id" and "ID", which are duplicates for a
> case-insensitive dialect.
> Expected output:
> {code:sql}
> SELECT "t"."id", "t0"."ID" AS "ID0"
> FROM (VALUES (1)) AS "t" ("id"),
> (VALUES (1)) AS "t0" ("ID"){code}
> I think RelToSqlConverter should uniquify generated output names using the
> target dialect's case-sensitivity.
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