[SPARK-16621] Generate stable SQLs in SQLBuilder

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.1, 2.1.0
• Component/s: SQL
• Assignee: Dongjoon Hyun
• Reporter: Dongjoon Hyun
• Created: 19/Jul/16 07:35
• Updated: 27/Jul/16 06:52
• Resolved: 27/Jul/16 05:28

Description

Currently, the generated SQLs have not-stable IDs for generated attributes.
The stable generated SQL will give more benefit for understanding or testing the queries. This issue provides stable SQL generation by the followings.

• Provide unique ids for generated subqueries, `gen_subquery_xxx`.
• Provide unique and stable ids for generated attributes, `gen_attr_xxx`.

*Before*

scala> new org.apache.spark.sql.catalyst.SQLBuilder(sql("select 1")).toSQL
res0: String = SELECT `gen_attr_0` AS `1` FROM (SELECT 1 AS `gen_attr_0`) AS gen_subquery_0

scala> new org.apache.spark.sql.catalyst.SQLBuilder(sql("select 1")).toSQL
res1: String = SELECT `gen_attr_4` AS `1` FROM (SELECT 1 AS `gen_attr_4`) AS gen_subquery_0

*After*

scala> new org.apache.spark.sql.catalyst.SQLBuilder(sql("select 1")).toSQL
res1: String = SELECT `gen_attr_0` AS `1` FROM (SELECT 1 AS `gen_attr_0`) AS gen_subquery_0

scala> new org.apache.spark.sql.catalyst.SQLBuilder(sql("select 1")).toSQL
res2: String = SELECT `gen_attr_0` AS `1` FROM (SELECT 1 AS `gen_attr_0`) AS gen_subquery_0

Issue Links

• links to: [Github] Pull Request #14257 (dongjoon-hyun)