[CALCITE-2933] In Druid adapter, expression like "cast(cast(\"timestamp\" as timestamp) as varchar)" returns as epoch millisecond

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.18.0
• Fix Version/s: 1.20.0
• Labels: pull-request-available
• Assignee: Danny Chen
• Reporter: Hongze Zhang
• Created: 19/Mar/19 07:20
• Updated: 24/Jun/19 15:02
• Resolved: 16/May/19 08:43

Description

SQL 1:

select cast("timestamp" as timestamp) as t from "foodmart" order by t limit 1

Result:

T=1997-01-01 00:00:00

SQL 2:

select cast(cast("timestamp" as timestamp) as varchar) as t from "foodmart" order by t limit 1

Result:

T=852076800000

The second query should returns with the same format as the first one.

See test case:
https://github.com/apache/calcite/blob/1229ef27094ea73ad9c7a397f442285c7e1df9b0/druid/src/test/java/org/apache/calcite/test/DruidAdapterIT2.java#L3930

Issue Links

• is part of: CALCITE-2932 DruidAdapterIT regression after 1.17 release
• is related to: CALCITE-2590 Remove redundant CAST when operand has exactly the same type as it is casted to
• is related to: CALCITE-2695 Simplify casts which are only widening nullability
• links to: GitHub Pull Request #1120