plan: improve row count estimation using column order correlation #9839
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
eurekaka
added
type/enhancement
|
/run-all-tests |
winoros
reviewed
Mar 21, 2019
winoros
reviewed
Mar 21, 2019
eurekaka
force-pushed
the
corr_estimation
branch
from
78ecb28 to
0f30d20
Compare
Codecov Report
@@ Coverage Diff @@
## master #9839 +/- ##
===========================================
Coverage ? 77.9438%
===========================================
Files ? 407
Lines ? 83555
Branches ? 0
===========================================
Hits ? 65126
Misses ? 13590
Partials ? 4839 |
eurekaka
force-pushed
the
corr_estimation
branch
from
5ff3017 to
13b6897
Compare
winoros
reviewed
Mar 28, 2019
qw4990
reviewed
Mar 28, 2019
qw4990
reviewed
Mar 28, 2019
alivxxx
reviewed
Apr 10, 2019
eurekaka
force-pushed
the
corr_estimation
branch
2 times, most recently
from
5acf74f to
e51ac82
Compare
|
/run-all-tests |
zz-jason
reviewed
Apr 24, 2019
| @@ -44,18 +44,3 @@ IndexLookUp_11 0.00 root | |||
| ├─IndexScan_8 1.00 cop table:outdated_statistics, index:a, b, range:[1 1,1 1], keep order:false | |||
| └─Selection_10 0.00 cop eq(test.outdated_statistics.c, 1) | |||
| └─TableScan_9 1.00 cop table:outdated_statistics, keep order:false | |||
| CREATE TABLE `unknown_correlation` ( | |||
There was a problem hiding this comment.
It's better to keep this test, or move it to another file. In order to discover plan regression.
There was a problem hiding this comment.
This test is moved to TestLimitCrossEstimation.
| for _, col := range cols { | ||
| hist, ok := histColl.Columns[col.ID] | ||
| if !ok { | ||
| return nil, 0 |
There was a problem hiding this comment.
Why breaking here? Should we continue to compare other columns?
There was a problem hiding this comment.
If we don't know correlation of a column, we assume they are independent, so the whole condition should be treated as independent?
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?
Fix #9067
What is changed and how it works?
When estimating row count for TableScan with Limit pushed down:
tidb_opt_correlation_thresholdandtidb_opt_correlation_exp_factor;Check List
Tests
Code changes
Side effects
Related changes