ddl: introduce a new system variable to control the `store-write-bwlimit` when ingesting (#57145) by ti-chi-bot · Pull Request #57378 · pingcap/tidb

ti-chi-bot · 2024-11-14T05:55:52Z

This is an automated cherry-pick of #57145

What problem does this PR solve?

Issue Number: close #57156

Problem Summary:

See the issue description

What changed and how does it work?

Introduce a new system variable to control the store-write-bwlimit when ingesting

Check List

Tests

Unit test
Integration test
Manual test (add detailed scripts or steps below)
No need to test
- I checked and no code files have been changed.

Manual test:

bootstrap a cluster
Turn on tidb_ddl_enable_fast_reorg, and with tidb_enable_dist_task on or off, do the following test:
1. set the tidb_ddl_reorg_max_write_speed to 1mb
2. add index for a table, the speed is slow
3. after setting the tidb_ddl_reorg_max_write_speed to 0(no limitation), the speed of adding index increases

For a table containing 200,000 rows:

TiDB root@127.0.0.1:test> select count(*) from t1;
+----------+
| count(*) |
+----------+
| 200000   |
+----------+
1 row in set
Time: 0.272s
TiDB root@127.0.0.1:test> select * from t1 limit 3;
+----+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| id | data                                                                                                                                                                                                                                                            |
+----+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 0  | fIhixzEuzMNSXLflhCwAktUGYYhXHfgqVHhmognLsnbaEQhXXvzJOehnEXunFcaeVoZSgLNXEFWTAWjfcPYCQRYNKRlHFGJCstAarZvqyeqwmJoHquIfGHFAUIUovzCeyisLSCrIeypScZdsubrPCcbiyBggiehBqnplnbRoVgNogIVdymQwXdUoyhXNzUzLdBhuqdYcznbnCbkZoFdPQiDYBhECaxNtGwbIjHqGsziqIZTHSxzxlmQVZrsUaRb |
| 1  | UdcuwmGBTvKnZbvFUISeLxhzCYmmGqBkTBodTGxKlPIheJffnZUezUAKzVSOCcIFyJxAGmWrqtJhIblTwOLuSPEbzyxGjStWbCrKQxndouhfvnbgeqzCWdNGcSPCjWOyKGixbEjHejDrCXOuhTVdMqouiEKhWPlqBGydoAVUSBHAVqSJdjIhgASkbzIWiFbrtgOMYuPqSqnoMnMaJdatMUoWofkVhRdxOorjyOyWtfaMKTdWdXxQvIjRmZUezRl |
| 2  | UJttwvfdAXHvQxCITRMoAvLNVElknAuGssAOciBtXzqtoiYISIiicCelyiWGNqjHKfXgqxUJWbbtlhFuEdhvlVPGrcwcArMwcmLaIxklvCDqOJnBNgoPMGTSQaMesuugXAuHHmgjgoIpkQGUdsCcAiDOhTmGBYhZfzqcdCXZNDOFiqOCsYQUCiFrMzEOOcZeJPTHGaZCsMHSQhXxcFqThkWUULEIQRlgBaQBgexlXOFqASzhtBGaFtRMcMlbIGF |
+----+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
3 rows in set
Time: 0.019s
TiDB root@127.0.0.1:test> show create table t1;
+-------+-------------------------------------------------------------+
| Table | Create Table                                                |
+-------+-------------------------------------------------------------+
| t1    | CREATE TABLE `t1` (                                         |
|       |   `id` int NOT NULL,                                        |
|       |   `data` varchar(255) DEFAULT NULL,                         |
|       |   PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */     |
|       | ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |
+-------+-------------------------------------------------------------+
1 row in set
Time: 0.013s

Setting tidb_ddl_reorg_max_write_speed from 4mb to unlimited would result in different speeds of adding index:

TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = '4mb';
Query OK, 0 rows affected
Time: 0.010s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 63.228s

TiDB root@127.0.0.1:test> alter table t1 drop index idx_data;
Query OK, 0 rows affected
Time: 0.107s
TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = '8mb';
Query OK, 0 rows affected
Time: 0.031s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 33.176s

TiDB root@127.0.0.1:test> alter table t1 drop index idx_data;
Query OK, 0 rows affected
Time: 0.105s
TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = '16mb';
Query OK, 0 rows affected
Time: 0.059s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 15.432s

TiDB root@127.0.0.1:test> alter table t1 drop index idx_data;
Query OK, 0 rows affected
Time: 0.220s
TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = '32mb';
Query OK, 0 rows affected
Time: 0.026s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 7.717s

TiDB root@127.0.0.1:test> alter table t1 drop index idx_data;
Query OK, 0 rows affected
Time: 0.139s
TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = '64mb';
Query OK, 0 rows affected
Time: 0.018s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 4.387s

TiDB root@127.0.0.1:test> alter table t1 drop index idx_data;
Query OK, 0 rows affected
Time: 0.140s
TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = '128mb';
Query OK, 0 rows affected
Time: 0.019s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 4.375s

TiDB root@127.0.0.1:test> alter table t1 drop index idx_data;
Query OK, 0 rows affected
Time: 0.096s
TiDB root@127.0.0.1:test> set @@global.tidb_ddl_reorg_max_write_speed = 0;
Query OK, 0 rows affected
Time: 0.038s
TiDB root@127.0.0.1:test> CREATE INDEX idx_data ON test.t1 (data)
Query OK, 0 rows affected
Time: 4.229s

With the tidb_ddl_reorg_max_write_speed increased, the metric shows that the number of write operations increased as expected

To verify that decreasing the tidb_ddl_reorg_max_write_speed helps to lower the impact of ADD INDEX on online service, we observe that with a further speed limitation, the QPS of sysbench increases.

Side effects

Performance regression: Consumes more CPU
Performance regression: Consumes more Memory
Breaking backward compatibility

Documentation

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Add a system variable tidb_ddl_reorg_max_write_speed to limit the speed of ingesting when adding index
增加系统变量 tidb_ddl_reorg_max_write_speed 来限制加索引时 ingesting 的速度上限

codecov · 2024-11-14T06:23:50Z

Codecov Report

Attention: Patch coverage is 70.83333% with 7 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-8.5@7d9ee81). Learn more about missing BASE report.

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##             release-8.5     #57378   +/-   ##
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================================================
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CbcWestwolf · 2024-11-14T06:48:32Z

/retest

ti-chi-bot · 2024-11-19T16:43:58Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tangenta, yudongusa

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ti-chi-bot · 2024-11-19T16:44:02Z

[LGTM Timeline notifier]

Timeline:

2024-11-19 09:11:33.479250949 +0000 UTC m=+952255.670119945: ☑️ agreed by tangenta.
2024-11-19 16:44:01.212728765 +0000 UTC m=+979403.403597758: ☑️ agreed by yudongusa.

CbcWestwolf added 5 commits November 14, 2024 05:55

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ti-chi-bot added release-note Denotes a PR that will be considered when it comes time to generate release notes. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. type/cherry-pick-for-release-8.5 This PR is cherry-picked to release-8.5 from a source PR. labels Nov 14, 2024

ti-chi-bot mentioned this pull request Nov 14, 2024

ddl: introduce a new system variable to control the store-write-bwlimit when ingesting #57145

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ti-chi-bot bot merged commit c104575 into pingcap:release-8.5 Nov 19, 2024

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ddl: introduce a new system variable to control the `store-write-bwlimit` when ingesting (#57145)#57378

ddl: introduce a new system variable to control the `store-write-bwlimit` when ingesting (#57145)#57378
ti-chi-bot[bot] merged 5 commits intopingcap:release-8.5from
ti-chi-bot:cherry-pick-57145-to-release-8.5

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