statistics: prioritize low selectivity indexes in the greedy search procedure of Selectivity()
#20038
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
…rocedure of `Selectivity()`
eurekaka
added
type/enhancement
eurekaka
requested review from
hanfei1991
and removed request for
a team and
hanfei1991
eurekaka
force-pushed
the
greedy_search
branch
2 times, most recently
from
584c75c
to
f07d698
Compare
|
Should it be cherry-picked to the release branch? |
ti-srebot
approved these changes
Sep 21, 2020
|
/merge |
ti-srebot
added
the
status/can-merge
|
/run-all-tests |
|
@eurekaka merge failed. |
|
/run-all-tests |
ti-srebot
pushed a commit
to ti-srebot/tidb
that referenced
this pull request
Sep 22, 2020
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
|
cherry pick to release-4.0 in PR #20154 |
zz-jason
pushed a commit
that referenced
this pull request
Oct 3, 2020
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Outdated suggestions cannot be applied.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.
What problem does this PR solve?
Issue Number: close #19904
Problem Summary:
Optimal index is not chosen when computing selectivity.
What is changed and how it works?
What's Changed:
Consider the selectivity of combined conditions in the greedy search procedure to choose the covering indexes.
How it Works:
Different indexes may indicate that different set of conditions are covered, we should prefer the combined conditions with lower selectivity. The rationale behind is that lower selectivity tends to reflect more functional dependencies between columns.
Related changes
Check List
Tests
Side effects
N/A
Release note
Selectivity()