[CALCITE-1998] Hive - Version specific handling for NULLS FIRST/ NULLS LAST

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.15.0
• Fix Version/s: 1.15.0
• Component/s: core
• External issue URL: https://github.com/apache/calcite/pull/545
• External issue ID: 545
• Assignee: Julian Hyde
• Reporter: Abbas Gadhia
• Created: 05/Oct/17 12:58
• Updated: 09/Dec/17 18:21
• Resolved: 02/Nov/17 23:27

Description

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.

1. Change the default NullCollation from HIGH to LOW
2. 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