planner,executor,infoschema: add system table table_storage_stats (#15056)

[ti-srebot]

cherry-pick #15056 to release-4.0

---

What problem does this PR solve?

we can only get the disk-usage from http API

What is changed and how it works?

1. This pr could help us by using the table_storage_stats get the usage of a table, if a table is empty or its size < 0, its TABLE_SIZE would return 1MB.
2. Extract the get PdRegionStats func to helper which used by http API and this sys table.

mysql> select * from table_storage_stats where table_schema = 'test';
+--------------+------------+----------+------------+--------------+--------------------+------------+------------+
| TABLE_SCHEMA | TABLE_NAME | TABLE_ID | PEER_COUNT | REGION_COUNT | EMPTY_REGION_COUNT | TABLE_SIZE | TABLE_KEYS |
+--------------+------------+----------+------------+--------------+--------------------+------------+------------+
| test         | t          |      143 |          3 |            1 |                  1 |          1 |          0 |
| test         | usertable  |      343 |          3 |           97 |                  0 |       9127 |   16605517 |
| test         | t2         |      348 |          3 |            1 |                  1 |          1 |          0 |
| test         | tcs1       |      360 |          3 |           70 |                  0 |       7087 |   10204927 |
| test         | tcs2       |      362 |          3 |           70 |                  0 |       7141 |    9712408 |
| test         | tcs3       |      364 |          3 |           70 |                  0 |       7174 |    9765219 |
+--------------+------------+----------+------------+--------------+--------------------+------------+------------+
6 rows in set (0.35 sec)


mysql> select count(*) from information_schema.TABLE_STORAGE_STATS;
+----------+
| count(*) |
+----------+
|     1249 |
+----------+

mysql> select * from table_storage_stats where table_schema = 'mysql'and table_name = 'tidb';
+--------------+------------+----------+------------+--------------+--------------------+------------+------------+
| TABLE_SCHEMA | TABLE_NAME | TABLE_ID | PEER_COUNT | REGION_COUNT | EMPTY_REGION_COUNT | TABLE_SIZE | TABLE_KEYS |
+--------------+------------+----------+------------+--------------+--------------------+------------+------------+
| mysql        | tidb       |       17 |          3 |            1 |                  1 |          1 |        134 |
+--------------+------------+----------+------------+--------------+--------------------+------------+------------+
1 row in set (0.12 sec)

Check List

Tests

• Integration test

Release note

• Add system table table_storage_stats

[ti-srebot]

/run-all-tests

[AilinKid]

Rest LGTM

[AilinKid]

LGTM

[ti-srebot]

@AilinKid, Thanks for your review, however we are sorry that your vote won't be count.

[tangenta]

LGTM

[ti-srebot]

@tangenta, Thanks for your review, however we are sorry that your vote won't be count.

[djshow832]

LGTM

[ti-srebot]

@djshow832, Thanks for your review, however we are sorry that your vote won't be count.

[crazycs520]

LGTM

[crazycs520]

/run-all-tests

[SunRunAway]

LGTM

[SunRunAway]

/merge

[ti-srebot]

Sorry @SunRunAway, this branch cannot be merged without an approval of release maintainers

[Hexilee]

/merge

[ti-srebot]

Sorry @Hexilee, this branch cannot be merged without an approval of release maintainers

[Hexilee]

/merge

[ti-srebot]

/run-all-tests

[SunRunAway]

/merge