[jira] [Commented] (CALCITE-1998) Hive - Version specific handling for NULLS FIRST/ NULLS LAST

["Abbas Gadhia (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16241626#comment-16241626 ] 

Abbas Gadhia commented on CALCITE-1998:
---------------------------------------

Hi [~julianhyde], I just noticed that the MysqlDialect still uses "x is null" instead of isnull(x). Did you intend to leave it that way or was it an oversight?

> Hive - Version specific handling for NULLS FIRST/ NULLS LAST
> ------------------------------------------------------------
>
>                 Key: CALCITE-1998
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1998
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.15.0
>            Reporter: Abbas Gadhia
>            Assignee: Julian Hyde
>            Priority: Minor
>             Fix For: 1.15.0
>
>
> This JIRA is for PR https://github.com/apache/calcite/pull/545
> We are making the HiveSqlDialect version aware for the NULLS FIRST and NULLS LAST feature. In https://issues.apache.org/jira/browse/HIVE-12994 , the authors clarified that the default NullCollation for Hive is "NullDirection.LOW". Currently, the DEFAULT set in Calcite for Hive is NullCollation.HIGH
> In this PR, we are making 2 changes.
> # Change the default NullCollation from HIGH to LOW
> # Add NullCollation emulation in the HiveSqlDialect when the version of the dialect is less that 2.1.0 or when the version is blank. 
> We're also adding a new Dialect "BigQuerySqlDialect" with the "quoteString" as "`" based on https://cloud.google.com/bigquery/docs/reference/standard-sql/lexical



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