dump: always split TiDB v3.* tables through tidb rowid to save TiDB's memory

[lichunzhu]

What problem does this PR solve?

fix #295, an extension of #273
In TiDB v3.x:

1. table INFORMATION_SCHEMA.TIKV_REGION_STATUS doesn't have table_name/table_schema.
2. doesn't have SHOW TABLE REGIONS statement.
3. table INFORMATION_SCHEMA.PARTITIONS doesn't actually have data.
4. doesn't have tidb_decode_key function.

mysql> show create table information_schema.TIKV_REGION_STATUS;
+--------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table              | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+--------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| TIKV_REGION_STATUS | CREATE TABLE `TIKV_REGION_STATUS` (
  `REGION_ID` bigint(21) unsigned DEFAULT NULL,
  `START_KEY` text DEFAULT NULL,
  `END_KEY` text DEFAULT NULL,
  `EPOCH_CONF_VER` bigint(21) unsigned DEFAULT NULL,
  `EPOCH_VERSION` bigint(21) unsigned DEFAULT NULL,
  `WRITTEN_BYTES` bigint(21) unsigned DEFAULT NULL,
  `READ_BYTES` bigint(21) unsigned DEFAULT NULL,
  `APPROXIMATE_SIZE` bigint(21) unsigned DEFAULT NULL,
  `APPROXIMATE_KEYS` bigint(21) unsigned DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |
+--------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

What is changed and how it works?

Split chunks by PKIsHandle for TiDB v3.*. Make sure TiDB won't OOM through splitting tables by rowids.
We do some staff by our own to solve the problem that tidb lacks some info.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  Test dump with v3.0.0. The result is looks expected.

Related changes

• Need to cherry-pick to the release branch

Release note

• Always split TiDB v3.* tables through tidb rowid to save TiDB's memory.

[lichunzhu]

@kennytm PTAL

[sleepymole]

How about using sort.Slice ?

[lichunzhu]

fixed

[Ehco1996]

what's this?

[lichunzhu]

It's region info read from TiDB. This is built by creating a table, inserting data and select * from information_schema.tikv_region_status. These three columns are region_id, start_key, end_key separately.

[Ehco1996]

oh it's test fixtures

[ti-chi-bot]

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[lichunzhu]

/merge

[ti-chi-bot]

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

Commit hash: 62c52a8

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #306.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #307.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #308.