[CALCITE-5285] CalcReduceExpressionsRule may transform to same rel

• Type: Bug
• Status: Reopened
• Priority: Major
• Resolution: Unresolved
• Component/s: server
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Krzysztof Ślusarski
• Created: 13/Sep/22 12:42
• Updated: 30/Nov/22 10:10

Description

Method CalcReduceExpressionsRule#onMatch enters the branch and calculates reduceExpressions() condition. If that one is true it creates new calc. Unfortunately logic in reduceExpressions() is different then in the rest of the method and it can create a calc that is equal to the input.

Example query SELECT floor(this / 1) FROM test.

Input calc contains program with exprs:

0 = {RexInputRef@11348} "$0"
1 = {RexInputRef@11349} "$1"
2 = {RexCall@11350} "CAST($t1):BIGINT(32)"
3 = {RexLiteral@11351} "1:BIGINT(32)"
4 = {RexCall@11352} "/($t2, $t3)"
5 = {RexCall@11353} "FLOOR($t4)"

The one on index 4 can be simplified (the division can be removed). That condition is met in reduceExpressions(),  but following logic in onMatch() doesn't simplify that expression. 

This makes the output calc equals to input one which breaks the rest of query optimizing.

 

Issue Links

• links to: GitHub Pull Request #2906