opt: support SplitScanIntoUnionScans for exclusive constraint boundaries#65350
Merged
craig[bot] merged 1 commit intocockroachdb:masterfrom May 18, 2021
Merged
opt: support SplitScanIntoUnionScans for exclusive constraint boundaries#65350craig[bot] merged 1 commit intocockroachdb:masterfrom
craig[bot] merged 1 commit intocockroachdb:masterfrom
Conversation
This commit adds support for applying the SplitScanIntoUnionScans rule in some cases if the constraint boundary is exclusive. For example, prior to this commit, SplitScanIntoUnionScans did not apply for the following query, even if an index was available on (x, y): SELECT x, y FROM tab WHERE (x = 0 OR x = 10) AND y IS NOT NULL ORDER BY y LIMIT 10 This was because the index constraint, (/0/NULL - /0] (/10/NULL - /10], had an exclusive boundary. This commit adds support for applying the rule in such cases, as long as the prefix length is shorter than the key length. In this case, the prefix length is 1 (for column x), and the key with the exclusive boundary has length 2, so it is valid to apply SplitScanIntoUnionScans. Release note (performance improvement): The optimizer can now avoid full table scans for queries with a LIMIT and ORDER BY clause in some additional cases where the ORDER BY columns are not a prefix of an index.
Member
|
This change is |
f684ff7 to
7c76659
Compare
mgartner
approved these changes
May 17, 2021
Contributor
mgartner
left a comment
There was a problem hiding this comment.
Cool!
Reviewed 3 of 3 files at r1.
Reviewable status:complete! 1 of 0 LGTMs obtained (waiting on @DrewKimball)
rytaft
commented
May 18, 2021
Contributor
|
Build succeeded: |
This file contains hidden or 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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
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.
This commit adds support for applying the
SplitScanIntoUnionScansrule in some cases if the constraint boundary is exclusive. For example,
prior to this commit,
SplitScanIntoUnionScansdid not apply for the followingquery, even if an index was available on (x, y):
This was because the index constraint,
(/0/NULL - /0] (/10/NULL - /10], had anexclusive boundary. This commit adds support for applying the rule in such
cases, as long as the prefix length is shorter than the key length. In this
case, the prefix length is 1 (for column x), and the key with the exclusive
boundary has length 2, so it is valid to apply
SplitScanIntoUnionScans.Release note (performance improvement): The optimizer can now avoid
full table scans for queries with a LIMIT and ORDER BY clause in some
additional cases where the ORDER BY columns are not a prefix of an index.