planner,executor,infoschema: add system tables tiflash_tables and tiflash_segments (#18092)

[ti-srebot]

cherry-pick #18092 to release-4.0

---

What problem does this PR solve?

we can read tiflash storage stat from tidb for the ease of debug.

What is changed and how it works?

What's Changed: add two new system tables tiflash_tables and tiflash_segments.

How it Works: it uses etcd client to get http port of tiflash nodes, and then get data from corresponding tiflash system tables through the http port.

mysql> select tidb_table,table_id,segment_count,tiflash_instance from tiflash_tables where tidb_database = 'test';
+------------+----------+---------------+------------------+
| tidb_table | table_id | segment_count | tiflash_instance |
+------------+----------+---------------+------------------+
| t          |       45 |             1 | 127.0.0.1:9500   |
| t2         |       47 |             1 | 127.0.0.1:9500   |
+------------+----------+---------------+------------------+
2 rows in set (0.01 sec)

mysql> select count(*) from tiflash_tables;
+----------+
| count(*) |
+----------+
|       22 |
+----------+
1 row in set (0.02 sec)

mysql> select tidb_table,table_id from tiflash_tables where tiflash_instance='127.0.0.1:9500' limit 5;
+------------------+----------+
| tidb_table       | table_id |
+------------------+----------+
| t                |       45 |
| t2               |       47 |
| tables_priv      |       11 |
| columns_priv     |       13 |
| global_variables |       15 |
+------------------+----------+
5 rows in set (0.02 sec)

mysql> select `tidb_table`,`segment_id`,`range`,`rows` from tiflash_segments where tidb_database='test';
+------------+------------+--------------------------------------------+------+
| tidb_table | segment_id | range                                      | rows |
+------------+------------+--------------------------------------------+------+
| t          |          1 | [-9223372036854775808,9223372036854775807) |    0 |
| t2         |          1 | [-9223372036854775808,9223372036854775807) |    0 |
+------------+------------+--------------------------------------------+------+
2 rows in set (0.01 sec)

mysql> select count(*) from tiflash_segments;
+----------+
| count(*) |
+----------+
|       22 |
+----------+
1 row in set (0.01 sec)

mysql> select `tidb_table`,`segment_id`,`range`,`rows` from tiflash_segments where tiflash_instance='127.0.0.1:9500' limit 5;
+------------------+------------+--------------------------------------------+------+
| tidb_table       | segment_id | range                                      | rows |
+------------------+------------+--------------------------------------------+------+
| t                |          1 | [-9223372036854775808,9223372036854775807) |   64 |
| t2               |          1 | [-9223372036854775808,9223372036854775807) |    0 |
| tables_priv      |          1 | [-9223372036854775808,9223372036854775807) |    0 |
| columns_priv     |          1 | [-9223372036854775808,9223372036854775807) |    0 |
| global_variables |          1 | [-9223372036854775808,9223372036854775807) |    0 |
+------------------+------------+--------------------------------------------+------+
5 rows in set (0.01 sec)

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Unit test
• Manual test: create a tidb cluster with three tiflash nodes, create 100000 tables in tidb，and then select from the two new added system tables to see whether the results meet expectation.

Release note

• Add system tables tiflash_tables and tiflash_segments

[ti-srebot]

/run-all-tests

[ti-srebot]

@lidezhu please accept the invitation then you can push to the cherry-pick pull requests.
https://github.com/ti-srebot/tidb/invitations

[lidezhu]

/run-all-tests

[lidezhu]

/run-all-tests

[crazycs520]

LGTM

[lidezhu]

/run-all-tests

[lidezhu]

/run-all-tests

[lidezhu]

/run-all-tests

[lidezhu]

/run-all-tests

[lidezhu]

/run-all-tests

[lidezhu]

/run-all-tests

[lidezhu]

@crazycs520 PTAL

[tangenta]

LGTM

[crazycs520]

/run-all-tests

[ti-srebot]

/run-all-tests