session, table: fix listColumnPartition data race (#33199)

[ti-srebot]

cherry-pick #33199 to release-6.0
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/34285

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/34285:release-6.0-1a19f959f454

---

What problem does this PR solve?

Issue Number: close #33030

Problem Summary:
ForListColumnPruning has a lot of fields, if we use the lock to fix data race, it will make the code dirty.
So I change the way to fix #32416.

#32416 :
In step 1

In the bootstrap phase, new collation is true
After bootstrap ends, new collation is false.

In step 2

a. In the bootstrap phase, new collation is true. ForListColumnPruning builds the hashMap(generate the partition hash key, by calling EncodeKey) in TableFromMeta

b. After bootstrap ends, new collation is false. The generated partition hash key(by calling EncodeKey) could not be found in the hashMap.

What is changed and how it works?

This way I will rebuild hashMap with new collation is false after step 2.a. Then we can find the key in step 2.b.

Check List

Tests

• Unit test
  Tests already exist: TestLocatePartition

• Integration test

• Manual test (add detailed scripts or steps below)

1. Set the new_collations_enabled_on_first_bootstrap item to false and run the SQL statements as follows:

set @@session.tidb_enable_list_partition = ON;
set @@tidb_partition_prune_mode = 'dynamic';
drop table if exists github_events;
CREATE TABLE `github_events` (
`id` bigint(20) DEFAULT NULL,
`type` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
PARTITION BY LIST COLUMNS(`type`)
(PARTITION `push_event` VALUES IN ("PushEvent"),
PARTITION `watch_event` VALUES IN ("WatchEvent")
);

2. Restart TiDB with new_collations_enabled_on_first_bootstrap = false and execute the following statements:

tidb> set @@session.tidb_enable_list_partition = ON;
Query OK, 0 rows affected (0.00 sec)

tidb> set @@tidb_partition_prune_mode = 'dynamic';
Query OK, 0 rows affected (0.00 sec)

tidb> desc select id,type from github_events  where  type = 'WatchEvent';
+-------------------------+----------+-----------+-----------------------+-------------------------------------------+
| id                      | estRows  | task      | access object         | operator info                             |
+-------------------------+----------+-----------+-----------------------+-------------------------------------------+
| TableReader_7           | 10.00    | root      | partition:watch_event | data:Selection_6                          |
| └─Selection_6           | 10.00    | cop[tikv] |                       | eq(test.github_events.type, "WatchEvent") |
|   └─TableFullScan_5     | 10000.00 | cop[tikv] | table:github_events   | keep order:false, stats:pseudo            |
+-------------------------+----------+-----------+-----------------------+-------------------------------------------+
3 rows in set (0.00 sec)

• No code

Side effects

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

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix the data race when using the list column partition.

[ti-chi-bot]

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[ti-srebot]

/run-all-tests

[ti-srebot]

@zimulala you're already a collaborator in bot's repo.

[xhebox]

closed for DMR version