planner, executor: enable inline projection for Limit #20288

pingyu · 2020-09-28T17:10:44Z

What problem does this PR solve?

Issue Number: part of #14428

Problem Summary:
Implement inline projection for Limit, part of #14428.

What is changed and how it works?

What's Changed:
Enable inline projection for LIMIT.

How it Works:
markChildrenUsedCols is applied to Limit.

Benchmark:

$ go test  -v -benchmem -run=XX -bench="BenchmarkLimitExec" -count 1
goos: darwin
goarch: amd64
pkg: github.com/pingcap/tidb/executor
BenchmarkLimitExec/(rows:30000,_offset:10000,_count:10000,_inline_projection:false)-12         	   20329	     58699 ns/op	   24373 B/op	     100 allocs/op
BenchmarkLimitExec/(rows:30000,_offset:10000,_count:10000,_inline_projection:true)-12          	  255342	      5157 ns/op	    3216 B/op	      34 allocs/op
PASS
ok  	github.com/pingcap/tidb/executor	60.073s

About 10x faster for a simple select i from t where j=1 limit 10000,10000
(i & j are both LongLong fields)

Related changes

PR to update pingcap/docs/pingcap/docs-cn:
No.
Need to cherry-pick to the release branch
No.

Check List

Tests

Unit test
Manual test (add detailed scripts or steps below)

mysql root@localhost:test1> explain select i from t1 where k=1;                                                                                                                                               
+-----------------------+----------+-----------+---------------+--------------------------------+
| id                    | estRows  | task      | access object | operator info                  |
+-----------------------+----------+-----------+---------------+--------------------------------+
| Projection_4          | 10.00    | root      |               | test1.t1.i                     |
| └─TableReader_7       | 10.00    | root      |               | data:Selection_6               |
|   └─Selection_6       | 10.00    | cop[tikv] |               | eq(test1.t1.k, 1)              |
|     └─TableFullScan_5 | 10000.00 | cop[tikv] | table:t1      | keep order:false, stats:pseudo |
+-----------------------+----------+-----------+---------------+--------------------------------+
4 rows in set
Time: 0.014s
mysql root@localhost:test1> explain select i from t1 where k=1 limit 3;                                                                                                                                       
+--------------------------+---------+-----------+---------------+--------------------------------+
| id                       | estRows | task      | access object | operator info                  |
+--------------------------+---------+-----------+---------------+--------------------------------+
| Limit_8                  | 3.00    | root      |               | offset:0, count:3              |
| └─TableReader_14         | 3.00    | root      |               | data:Limit_13                  |
|   └─Limit_13             | 3.00    | cop[tikv] |               | offset:0, count:3              |
|     └─Selection_12       | 3.00    | cop[tikv] |               | eq(test1.t1.k, 1)              |
|       └─TableFullScan_11 | 3000.00 | cop[tikv] | table:t1      | keep order:false, stats:pseudo |
+--------------------------+---------+-----------+---------------+--------------------------------+
5 rows in set
Time: 0.014s
mysql root@localhost:test1>

Side effects

Performance regression
- Consumes more CPU
  No.
- Consumes more MEM
  No.
Breaking backward compatibility
No.

Release note

Support inline projection for Limit

…r_limit_inline_proj

pingyu · 2020-09-28T17:15:52Z

/run-all-tests

pingyu · 2020-09-28T18:59:06Z

/run-all-tests

planner/core/logical_plans.go

planner/core/physical_plans.go

planner/core/rule_column_pruning.go

planner/core/logical_plans.go

util/chunk/chunk.go

pingyu · 2020-10-11T14:55:49Z

/run-all-tests

pingyu · 2020-10-11T15:05:17Z

/run-unit-test

pingyu · 2020-10-11T15:44:34Z

All comments are addressed or replied, PTAL~ @SunRunAway

(Failure of unit-test was caused by infosync.GetAllServerInfo timeout in domain_test.go, and should not be relevant to this PR)

[2020-10-11T15:11:41.828Z] === RUN   TestInfo
...
[2020-10-11T15:11:41.829Z] [2020/10/11 23:10:16.965 +08:00] [WARN] [syncer.go:305] ["[ddl] etcd-cli delete key failed"] [key=/tidb/server/info/957e7044-c832-467c-827d-39ebacf3dc20] [error="context deadline exceeded"] [retryCnt=0]
[2020-10-11T15:11:41.829Z] [2020/10/11 23:10:18.409 +08:00] [INFO] [info.go:773] ["get key failed"] [key=/tidb/server/info] [error="context deadline exceeded"]
[2020-10-11T15:11:41.829Z] [2020/10/11 23:10:19.609 +08:00] [INFO] [info.go:773] ["get key failed"] [key=/tidb/server/info] [error="context deadline exceeded"]
[2020-10-11T15:11:41.829Z] [2020/10/11 23:10:20.810 +08:00] [INFO] [info.go:773] ["get key failed"] [key=/tidb/server/info] [error="context deadline exceeded"]
[2020-10-11T15:11:41.829Z] [2020/10/11 23:10:22.010 +08:00] [INFO] [info.go:773] ["get key failed"] [key=/tidb/server/info] [error="context deadline exceeded"]
[2020-10-11T15:11:41.829Z] [2020/10/11 23:10:23.211 +08:00] [INFO] [info.go:773] ["get key failed"] [key=/tidb/server/info] [error="context deadline exceeded"]
...
[2020-10-11T15:11:41.829Z] --- FAIL: TestInfo (13.08s)
[2020-10-11T15:11:41.829Z]     domain_test.go:220: err context deadline exceeded, infos map[]
[2020-10-11T15:11:41.829Z] FAIL
[2020-10-11T15:11:41.829Z] coverage: 83.3% of statements
[2020-10-11T15:11:41.829Z] FAIL	github.com/pingcap/tidb/domain	42.953s

planner/core/rule_build_key_info.go

SunRunAway · 2020-10-15T05:53:27Z

/reward 750

ti-challenge-bot · 2020-10-15T05:53:30Z

This PR's linked issue is not picked.

SunRunAway · 2020-10-15T06:37:37Z

/cc @XuHuaiyu

SunRunAway · 2020-10-15T07:23:51Z

/reward 750

ti-challenge-bot · 2020-10-15T07:23:56Z

Reward success.

SunRunAway · 2020-10-15T11:55:03Z

/cc @qw4990

qw4990

LGTM

qw4990 · 2020-10-15T12:50:48Z

/merge

ti-srebot · 2020-10-15T12:53:45Z

/run-all-tests

ti-srebot · 2020-10-15T13:05:12Z

@pingyu merge failed.

pingyu · 2020-10-18T03:11:20Z

/run-all-tests

XuHuaiyu · 2020-10-19T02:48:03Z

/merge

ti-srebot · 2020-10-19T02:48:12Z

/run-all-tests

ti-challenge-bot · 2020-10-19T02:55:17Z

@pingyu, Congratulations, you get 750 in this PR, and your total score is 750 in high-performance challenge program.

More

Tip : None

Warning:
The pull request merged, pingyu got the score. But it seems linked issue not picked.

cc: Mentor @SunRunAway

…p#20288)" This reverts commit 4501f6d.

pingyu added 9 commits September 23, 2020 02:26

executor: inline projection for limit

bed804b

wip pingcap#14428

f92d7fa

Merge branch 'master' of https://github.com/pingcap/tidb into executo…

e10c5bc

…r_limit_inline_proj

improve codes

a60340c

Merge branch 'master' into executor_limit_inline_proj

fcf637d

improve codes

f5d1283

fix unittest

165d463

Merge branch 'master' of https://github.com/pingcap/tidb into executo…

f9534d7

…r_limit_inline_proj

improve codes; add benchmark

c17d53d

pingyu requested review from a team as code owners September 28, 2020 17:10

pingyu requested review from SunRunAway and removed request for a team September 28, 2020 17:10

ti-srebot added the contribution This PR is from a community contributor. label Sep 28, 2020

improve benchmark

8bc17b1

github-actions bot added the sig/execution SIG execution label Sep 28, 2020

bug fix. add unit tests

21f49f5

hi-rustin mentioned this pull request Sep 29, 2020

challenge bot should not report error when the challenge program is not reward ti-community-infra/ti-challenge-bot#150

Closed

1 task

SunRunAway reviewed Oct 10, 2020

View reviewed changes

pingyu added 3 commits October 10, 2020 20:58

Merge branch 'master' into executor_limit_inline_proj

03434d4

address comments

919354c

improve BuildKeyInfo implementation

de436ef

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SunRunAway reviewed Oct 12, 2020

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planner/core/rule_build_key_info.go Show resolved Hide resolved

try chunk.Prune

fd47280

ti-srebot requested a review from XuHuaiyu October 15, 2020 06:37

ti-challenge-bot bot added the rewarded label Oct 15, 2020

SunRunAway mentioned this pull request Oct 15, 2020

Support inline projection for executors #14428

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9 tasks

ti-srebot requested a review from qw4990 October 15, 2020 11:55

qw4990 approved these changes Oct 15, 2020

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ti-srebot added status/can-merge Indicates a PR has been approved by a committer. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Oct 15, 2020

ti-srebot approved these changes Oct 15, 2020

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ti-srebot added the status/LGT2 Indicates that a PR has LGTM 2. label Oct 15, 2020

Merge branch 'master' into executor_limit_inline_proj

4e91cfd

Merge branch 'master' into executor_limit_inline_proj

e756808

ti-srebot merged commit 4501f6d into pingcap:master Oct 19, 2020

pingyu mentioned this pull request Oct 20, 2020

planner, executor: enable inline projection for Selection #20335

Closed

francis0407 mentioned this pull request Nov 3, 2020

planner: support stable result mode #20765

Closed

bb7133 added a commit to bb7133/tidb that referenced this pull request May 14, 2021

Revert "planner, executor: enable inline projection for Limit (pingca…

4b53b35

…p#20288)" This reverts commit 4501f6d.

mjonss mentioned this pull request May 17, 2021

Wrong value when query a partition table with LIMIT #24636

Closed

eurekaka mentioned this pull request Jun 10, 2021

panic may happen when limit is on top of window functions #25344

Closed

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planner, executor: enable inline projection for Limit #20288

planner, executor: enable inline projection for Limit #20288

pingyu commented Sep 28, 2020 •

edited by SunRunAway

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planner, executor: enable inline projection for Limit #20288

planner, executor: enable inline projection for Limit #20288

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pingyu commented Sep 28, 2020 • edited by SunRunAway Loading

What problem does this PR solve?

What is changed and how it works?

Related changes

Check List

Release note

pingyu commented Sep 28, 2020

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