[41] Fix count on all null VALUES clause #70
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Cherry pick apache#13029
Before the change, the
ValuesExec
containingNullArray
would incorrectly report column statistics as being non-null, which would misinformAggregateStatistics
optimizer and foldcount(always_null)
into row count instead of 0.This commit fixes the column statistics derivation for values with
NullArray
and therefore fixes execution of logical plans with count over such values.Note that the bug was not reproducible using DataFusion SQL frontend, because in DataFusion SQL the
VALUES (NULL)
doesn't have typeDataType:Null
(it has some apparently arbitrarily picked type instead).As a follow-up, all usages of
Array:null_count
should be inspected. The function can easily be misused (it returns "physical nulls", which do not exist for null type).