syncer(dm): Add unit test and integration test for multi-schema change when encountering "invalid connection" error

[lyzx2001]

What problem does this PR solve?

Issue Number: ref #4689

What is changed and how it works?

I have added unit test and integration test for multi-schema change when encountering "invalid connection" error, as additional tests for #6848. The running results have proved that the current logic works correctly for the multi-schema change situation as well.

According to experiments, the behavior of DM and TiDB is slightly different for multi-schema change.
Suppose we execute ALTER TABLE gbk.invalid_conn_test2 MODIFY i SMALLINT NOT NULL DEFAULT '0', MODIFY j SMALLINT NOT NULL DEFAULT '0' in DM and manually in TiDB separately.

For DM:

mysql>  ADMIN SHOW DDL JOBS;
+--------+---------+--------------------+-----------------------------------+--------------+-----------+----------+-----------+---------------------+---------------------+---------------------+--------+
| JOB_ID | DB_NAME | TABLE_NAME         | JOB_TYPE                          | SCHEMA_STATE | SCHEMA_ID | TABLE_ID | ROW_COUNT | CREATE_TIME         | START_TIME          | END_TIME            | STATE  |
+--------+---------+--------------------+-----------------------------------+--------------+-----------+----------+-----------+---------------------+---------------------+---------------------+--------+
|   1140 | gbk     | invalid_conn_test2 | modify column                     | public       |      1102 |     1135 |         0 | 2022-09-15 19:13:25 | 2022-09-15 19:13:25 | 2022-09-15 19:13:27 | synced |
|   1139 | gbk     | invalid_conn_test2 | modify column                     | public       |      1102 |     1135 |         0 | 2022-09-15 19:13:22 | 2022-09-15 19:13:22 | 2022-09-15 19:13:25 | synced |
| ...                                                                                                                                                                                                    |
+--------+---------+--------------------+-----------------------------------+--------------+-----------+----------+-----------+---------------------+---------------------+---------------------+--------+
10 rows in set (0.01 sec)

mysql> ADMIN SHOW DDL JOB QUERIES LIMIT 10 OFFSET 0;
+--------+----------------------------------------------------------------------------------------------------------------------------------------+
| JOB_ID | QUERY                                                                                                                                  |
+--------+----------------------------------------------------------------------------------------------------------------------------------------+
| 1140   | ALTER TABLE `gbk`.`invalid_conn_test2` MODIFY COLUMN `j` SMALLINT(4) NOT NULL DEFAULT '0'                                              |
| 1139   | ALTER TABLE `gbk`.`invalid_conn_test2` MODIFY COLUMN `i` SMALLINT(4) NOT NULL DEFAULT '0'                                              |
| ...                                                                                                                                             |
+--------+----------------------------------------------------------------------------------------------------------------------------------------+
10 rows in set (0.00 sec)

The multi-schema change DDL would be separated into two or more single DDL, and are executed by order one by one.

For manually operated in TiDB:

mysql> ADMIN SHOW DDL JOBS;
+--------+------------------+--------------------+---------------------------------+--------------+-----------+----------+-----------+---------------------+---------------------+---------------------+---------------+
| JOB_ID | DB_NAME          | TABLE_NAME         | JOB_TYPE                        | SCHEMA_STATE | SCHEMA_ID | TABLE_ID | ROW_COUNT | CREATE_TIME         | START_TIME          | END_TIME            | STATE         |
+--------+------------------+--------------------+---------------------------------+--------------+-----------+----------+-----------+---------------------+---------------------+---------------------+---------------+
|   2273 | gbk              | invalid_conn_test2 | alter table multi-schema change | none         |      2204 |     2271 |         0 | 2022-09-16 19:43:36 | 2022-09-16 19:43:36 | 2022-09-16 19:43:43 | synced        |
|   2273 | gbk              | invalid_conn_test2 | modify column /* subjob */      | public       |      2204 |     2271 |         0 | NULL                | NULL                | NULL                | done          |
|   2273 | gbk              | invalid_conn_test2 | modify column /* subjob */      | public       |      2204 |     2271 |         0 | NULL                | NULL                | NULL                | done          |
| ...                                                                                                                                                                                                                  |
+--------+------------------+--------------------+---------------------------------+--------------+-----------+----------+-----------+---------------------+---------------------+---------------------+---------------+
18 rows in set (0.01 sec)

mysql> ADMIN SHOW DDL JOB QUERIES LIMIT 10 OFFSET 0;
+--------+-------------------------------------------------------------------------------------------------------------------+
| JOB_ID | QUERY                                                                                                             |
+--------+-------------------------------------------------------------------------------------------------------------------+
| 2273   | ALTER TABLE gbk.invalid_conn_test2 MODIFY i SMALLINT NOT NULL DEFAULT '0', MODIFY j SMALLINT NOT NULL DEFAULT '0' |
| ...                                                                                                                        |
+--------+-------------------------------------------------------------------------------------------------------------------+
10 rows in set (0.01 sec)

The multi-schema change DDL would be separated into two or more subjob. The history returned by ADMIN SHOW DDL JOBS would contain both the subjobs and the original multi-schema change job. The history returned by ADMIN SHOW DDL JOB QUERIES LIMIT 10 OFFSET 0 would only contain the original multi-schema change job but not the subjobs.

I have added a unit test to test the manual TiDB situations since other unit tests have already covered the DM situations. I have added several integration tests to test the DM situations.

Check List

Tests

• Unit test
• Integration test

Questions

Will it cause performance regression or break compatibility?

No.

Do you need to update user documentation, design documentation or monitoring documentation?

No.

Release note

Fix the issue that dm-worker keeps retrying to execute ddl for every 5 minutes when encountering "invalid connection" error (works for multi-schema change as well).

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• GMHDBJD
• lance6716

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[lyzx2001]

/cc @lance6716

[codecov-commenter]

Codecov Report

Merging #7104 (93b3f4f) into master (f4754e1) will increase coverage by 6.0358%.
The diff coverage is 9.8039%.

Additional details and impacted files

Flag	Coverage Δ
cdc	67.5551% <ø> (+0.1075%)	⬆️
dm	?
engine	60.9629% <9.8039%> (-0.0056%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

@@               Coverage Diff                @@
##             master      #7104        +/-   ##
================================================
+ Coverage   59.8150%   65.8508%   +6.0358%     
================================================
  Files           803        565       -238     
  Lines         92129      52218     -39911     
================================================
- Hits          55107      34386     -20721     
+ Misses        32213      15171     -17042     
+ Partials       4809       2661      -2148     

[lance6716]

/cc @GMHDBJD

[GMHDBJD]

/run-all-tests

[GMHDBJD]

LGTM

[lance6716]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 2a4d28a

[lyzx2001]

/run-all-tests

[lance6716]

/hold

waiting refine tests and codes

[lance6716]

/run-dm-integration-test

[lance6716]

/run-all-tests

[lyzx2001]

/run-all-tests

[lance6716]

/unhold
/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 39cef26

[lyzx2001]

/run-all-tests

[lance6716]

/hold

need to fix CI

[lyzx2001]

/run-all-tests

[lyzx2001]

/run-all-tests

[lyzx2001]

/run-all-tests

[lyzx2001]

/run-all-tests

[lance6716]

/run-dm-integration-test

[lance6716]

/run-dm-integration-test

[lance6716]

/run-dm-integration-test

[lance6716]

/unhold
/merge

[ti-chi-bot]

@lyzx2001: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[lance6716]

/run-engine-integration-test

[lance6716]

/run-engine-integration-test