*: add show table regions syntax

[crazycs520]

What problem does this PR solve?

Related Parser PR: pingcap/parser#349
Add sql syntax to check split table region status.

SHOW TABLE [table_name] REGIONS

SHOW TABLE [table_name] INDEX [index_name] REGIONS;

What is changed and how it works?

eg

tidb > create table t (a int, b int, index idx(a));
Query OK, 0 rows affected
Time: 0.077s
tidb > split table t between (0) and (10000000000000000) regions 10;
Query OK, 0 rows affected
Time: 0.046s
tidb > split table t index idx between (0) and (1000000000) regions 4;
Query OK, 0 rows affected
Time: 0.408s
mysql>show table t regions;
+-----------+-------------------------------------+-------------------------------------+-----------+-----------------+------------------+------------+
| REGION_ID | START_KEY                           | END_Key                             | LEADER_ID | LEADER_STORE_ID | PEERS            | SCATTERING |
+-----------+-------------------------------------+-------------------------------------+-----------+-----------------+------------------+------------+
| 2173      | t_89_i_1_03800000002cb4178003000000 | t_89_r_1000000000000000             | 2177      | 5               | 2175, 2176, 2177 | 0          |
| 2178      | t_89_r_1000000000000000             | t_89_r_2000000000000000             | 2179      | 6               | 2179, 2183, 2243 | 0          |
| 2184      | t_89_r_2000000000000000             | t_89_r_3000000000000000             | 2186      | 2               | 2186, 2187, 2245 | 0          |
| 2188      | t_89_r_3000000000000000             | t_89_r_4000000000000000             | 2193      | 5               | 2191, 2193, 2192 | 0          |
| 2194      | t_89_r_4000000000000000             | t_89_r_5000000000000000             | 2196      | 2               | 2195, 2196, 2198 | 0          |
| 2199      | t_89_r_5000000000000000             | t_89_r_6000000000000000             | 2202      | 13              | 2201, 2202, 2203 | 0          |
| 2204      | t_89_r_6000000000000000             | t_89_r_7000000000000000             | 2205      | 6               | 2205, 2208, 2241 | 0          |
| 2210      | t_89_r_7000000000000000             | t_89_r_8000000000000000             | 2213      | 13              | 2211, 2212, 2213 | 0          |
| 2214      | t_89_r_8000000000000000             | t_89_r_9000000000000000             | 2218      | 5               | 2217, 2218, 2219 | 0          |
| 3         | t_89_r_9000000000000000             |                                     | 122       | 6               | 122, 2066, 2073  | 0          |
| 2225      | t_89_i_1_                           | t_89_i_1_03800000000ee6b28003000000 | 2228      | 5               | 2227, 2228, 2229 | 0          |
| 2230      | t_89_i_1_03800000000ee6b28003000000 | t_89_i_1_03800000001dcd650003000000 | 2234      | 6               | 2231, 2234, 2235 | 0          |
| 2236      | t_89_i_1_03800000001dcd650003000000 | t_89_i_1_03800000002cb4178003000000 | 2238      | 13              | 2237, 2238, 2239 | 0          |
+-----------+-------------------------------------+-------------------------------------+-----------+-----------------+------------------+------------+
13 rows in set
Time: 0.012s
mysql>show table t index idx regions;
+-----------+-------------------------------------+-------------------------------------+-----------+-----------------+------------------+------------+
| REGION_ID | START_KEY                           | END_Key                             | LEADER_ID | LEADER_STORE_ID | PEERS            | SCATTERING |
+-----------+-------------------------------------+-------------------------------------+-----------+-----------------+------------------+------------+
| 2225      | t_89_i_1_                           | t_89_i_1_03800000000ee6b28003000000 | 2228      | 5               | 2227, 2228, 2229 | 0          |
| 2230      | t_89_i_1_03800000000ee6b28003000000 | t_89_i_1_03800000001dcd650003000000 | 2234      | 6               | 2231, 2234, 2235 | 0          |
| 2236      | t_89_i_1_03800000001dcd650003000000 | t_89_i_1_03800000002cb4178003000000 | 2238      | 13              | 2237, 2238, 2239 | 0          |
| 2173      | t_89_i_1_03800000002cb4178003000000 | t_89_r_1000000000000000             | 2177      | 5               | 2175, 2176, 2177 | 0          |
+-----------+-------------------------------------+-------------------------------------+-----------+-----------------+------------------+------------+

Check List

Tests

• Unit test

Code changes

Side effects

Related changes

[ngaut]

PTAL @morgo

[morgo]

Should we call the syntax ADMIN SPLIT TABLE .. instead? It is not a strong preference, but there is an advantage to having all TiDB extensions under one namespace.

[crazycs520]

@morgo, Great, I will change this syntax later.

[morgo]

@morgo, Great, I will change this syntax later.

No problem! Don't feel you have to follow this advice if it doesn't make sense to you. ADMIN commands all explicitly require super privilege for now. If this doesn't make sense to SPLIT TABLE, feel free to take a different path.

[winkyao]

@morgo ADMIN requires super privilege, it will hurt the usability of SPLIT TABLE statement. So I think to keep SPLIT TABLE syntax is better?

[morgo]

@morgo ADMIN requires super privilege, it will hurt the usability of SPLIT TABLE statement. So I think to keep SPLIT TABLE syntax is better?

@winkyao you are right. We may need to take a look at other admin commands (ADMIN CHECKSUM TABLE) too, but that's a separate discussion. Let's keep it as split for now.

[crazycs520]

@morgo , I want to change this syntax to SHOW TABLE table_name [INDEX] [index_name] regions.

Because of I found that syntax is nothing to do with the split table. I can just use this syntax to check the table regions status/information.

[morgo]

@morgo , I want to change this syntax to SHOW TABLE table_name [INDEX] [index_name] regions.

Because of I found that syntax is nothing to do with the split table. I can just use this syntax to check the table regions status/information.

LGTM (assuming this command is read-only of course).

[codecov]

Codecov Report

Merging #10612 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master    #10612   +/-   ##
=========================================
  Coverage   81.261%   81.261%           
=========================================
  Files          423       423           
  Lines        91334     91334           
=========================================
  Hits         74219     74219           
  Misses       11822     11822           
  Partials      5293      5293

[winkyao]

rest LGTM

[tiancaiamao]

LGTM @winkyao

[winkyao]

LGTM

[crazycs520]

/run-all-tests