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https://issues.apache.org/jira/browse/CALCITE-5526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17689357#comment-17689357
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TJ Banghart edited comment on CALCITE-5526 at 2/15/23 9:43 PM:
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[~wnoble] Elsewhere you expressed concern over relying on
{{CalciteCatalogReader}} within {{{}SqlDialect{}}}. Could you restate those
concerns here? That seemed like a reasonable approach since any user defined
types will be mapped to a schema.
Alternatively, shouldn't specific {{SqlDialect}} classes just handle this by
overriding {{unparseDateTimeLiteral}} and related methods? (ex.
[Clickhouse|https://github.com/apache/calcite/blob/79879f92abc4f2279496a0e6ca9066d9d24a1457/core/src/main/java/org/apache/calcite/sql/dialect/ClickHouseSqlDialect.java#L121-L136])
was (Author: tjbanghart):
[~wnoble] Elsewhere you expressed concern on relying on
{{CalciteCatalogReader}} within {{{}SqlDialect{}}}. Could you restate those
concerns here? That seemed like a reasonable approach since any user defined
types will be mapped to a schema.
Alternatively, shouldn't specific {{SqlDialect}} classes just handle this by
overriding {{unparseDateTimeLiteral}} and related methods? (ex.
[Clickhouse|https://github.com/apache/calcite/blob/79879f92abc4f2279496a0e6ca9066d9d24a1457/core/src/main/java/org/apache/calcite/sql/dialect/ClickHouseSqlDialect.java#L121-L136])
> Handle unparsing of literals based on type system
> -------------------------------------------------
>
> Key: CALCITE-5526
> URL: https://issues.apache.org/jira/browse/CALCITE-5526
> Project: Calcite
> Issue Type: Task
> Reporter: Will Noble
> Assignee: Will Noble
> Priority: Minor
>
> CALCITE-5424 dealt with parsing date/time literals via a custom type system,
> however there is still no way to unparse them via the same type system. This
> is handled in
> [SqlDialect.unparseDateTimeLiteral|https://github.com/apache/calcite/blob/a0e119ea42def418957f214f539469f1aba76c18/core/src/main/java/org/apache/calcite/sql/SqlDialect.java#L468]
> which simply calls the literal object's {{toString()}} method.
> The literal object (a subclass of {{SqlAbstractDateTimeLiteral}}) should not
> be able to determine it's own unparsed representation by itself since it
> could be unparsed in any dialect. Since the current system for resolving
> custom types relies on access to the catalog, it appears we'll need to
> introduce to {{SqlDialect}} a dependency on {{CalciteCatalogReader}} so it
> can use the same mappings for unparsing as it does for parsing.
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