[CALCITE-2150] CurrentTimestamp is reduced in subquery

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Jark Wu
• Created: 25/Jan/18 05:57
• Updated: 22/Feb/19 01:19

Description

I add two unit test with ReduceExpressionsRule.PROJECT_INSTANCE reduce rule in the commit: https://github.com/wuchong/calcite/commit/e76c3ad3cc3ddc5c0bb0c3e385a71296329a7cb5

The first query is  "select sal, current_timestamp as t from emp" and the current_timestamp is not reduced as expected.

But the second query "select sal, sal + 5, t from (select sal, current_timestamp as t from emp)" the optimized plan is as following:
 

 LogicalProject(SAL=[$0], EXPR$1=[+($0, 5)], T=[2011-07-20 00:00:00])
   LogicalProject(SAL=[$5], T=[CURRENT_TIMESTAMP])
     LogicalTableScan(table=[[CATALOG, SALES, EMP]]

 

The current_timestamp in the outer Project is reduced as a constant: 2011-07-20 00:00:00 which maybe a bug I think.