fix: Use the right row container to extract rows in grouping set #11899
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Summary: Currently we always extract rows from grouping set through the default row container in the grouping set. It can cause potential performance and even data correctness problem in spill path as the row extract depends on the column stats recorded in the row container to decide whether apply fast no null path or slow path with nulls. If we use default row container to extract rows from the row container used by spill, the column stats is not accurate. If spill merge row container has null, then we get random non-null value for non column. This is correctness problem. If spill merge row container has no null, then we get slow path with null handling This PR fixes by always use the right container to extract rows Differential Revision: D67352373
facebook-github-bot
added
the
CLA Signed
|
This pull request was exported from Phabricator. Differential Revision: D67352373 |
✅ Deploy Preview for meta-velox canceled.
|
Yuhta
approved these changes
Dec 17, 2024
They are all covered once we optimize the row container column stats. |
|
This pull request has been merged in 2d2cdbd. |
athmaja-n
pushed a commit
to athmaja-n/velox
that referenced
this pull request
Jan 10, 2025
…ebookincubator#11899) Summary: Pull Request resolved: facebookincubator#11899 Currently we always extract rows from grouping set through the default row container in the grouping set. It can cause potential performance and even data correctness problem in spill path as the row extract depends on the column stats recorded in the row container to decide whether apply fast no null path or slow path with nulls. If we use default row container to extract rows from the row container used by spill, the column stats is not accurate. If spill merge row container has null, then we get random non-null value for non column. This is correctness problem. If spill merge row container has no null, then we get slow path with null handling This PR fixes by always use the right container to extract rows Reviewed By: Yuhta Differential Revision: D67352373 fbshipit-source-id: 9d48857c4b3ca270bfc6777e0c3e4fbc03ee1e03
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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.
Summary:
Currently we always extract rows from grouping set through the default row container in the grouping set.
It can cause potential performance and even data correctness problem in spill path as the row extract depends
on the column stats recorded in the row container to decide whether apply fast no null path or slow path with nulls.
If we use default row container to extract rows from the row container used by spill, the column stats is not accurate.
If spill merge row container has null, then we get random non-null value for non column. This is correctness problem.
If spill merge row container has no null, then we get slow path with null handling
This PR fixes by always use the right container to extract rows
Differential Revision: D67352373