[CALCITE-6507] Random functions are incorrectly considered deterministic

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.37.0
• Fix Version/s: 1.38.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Ruben Q L
• Reporter: Ruben Q L
• Created: 31/Jul/24 07:53
• Updated: 17/Oct/24 22:41
• Resolved: 17/Oct/24 22:41

Description

RAND, RANDOM, and RAND_INTEGER don't override the isDeterministic method, so they get the default behavior, i.e. true, which is incorrect.

This can lead to undesired consequences, e.g.:
A) RelMetadataQuery#getPulledUpPredicates can consider them as constants (and place them inside RelOptPredicateList#constantMap) since RelMdPredicates calls RexUtil#isConstant, which uses a ConstantFinder that evaluates whether a RexCall is constant or not based on the operator's isDeterministic value.
B) As a consequence of A) SortRemoveConstantKeyRule can incorrectly remove an "ORDER BY RAND()"

Issue Links

• links to: GitHub Pull Request #3893