[jira] [Assigned] (CALCITE-5885) SqlNode#toSqlString() does not honor dialect's supportsCharSet() flag on nested types

["Jiajun Xie (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-5885?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jiajun Xie reassigned CALCITE-5885:
-----------------------------------

    Assignee: Jiajun Xie

> SqlNode#toSqlString() does not honor dialect's supportsCharSet() flag on nested types
> -------------------------------------------------------------------------------------
>
>                 Key: CALCITE-5885
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5885
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Chris Rice
>            Assignee: Jiajun Xie
>            Priority: Minor
>         Attachments: CharsetTest.java
>
>
> Say we generate a RelNode corresponding to
> {code:java}
> SELECT CAST(c AS VARCHAR) FROM t
> {code}
> and we were to "unparse" that rel node back into the Postgres SQL dialect using
> {code:java}
> var converter = new RelToSqlConverter(PostgresqlSqlDialect.DEFAULT);
> SqlImplementor.Result result = converter.visitRoot(rel);
> SqlNode sqlNode = result.asStatement();
> var sql = sqlNode.toSqlString(PostgresqlSqlDialect.DEFAULT).getSql();
> {code}
> it would generate something like:
> {code:java}
> SELECT CAST("c" AS VARCHAR) AS "c"
> FROM "t"
> {code}
> Note that there is no charset information included in the cast, since the {{PostgresSqlDialect}} specifies that it does not support char sets:
> {code:java}
>   @Override public boolean supportsCharSet() {
>     return false;
>   }
> {code}
> Given that, we would expect that unparsing
> {code:java}
> SELECT CAST(c AS VARCHAR ARRAY) FROM t
> {code}
> back into SQL would also generate a type with no charset specified, but it in fact generates
> {code:java}
> SELECT CAST("c" AS VARCHAR CHARACTER SET "ISO-8859-1" ARRAY) AS "c"
> FROM "t"
> {code}
> This seems to come from the way `SqlTypeUtil.convertTypeToSpec()` handles collection types.



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