Add executor runtime info for explain for connection statement

[crazycs520]

This is a subtask of #17692

background

Currently, you can use explain for connection statement to check the plan information of the running sql, such as below:

 explain for connection 168;
+---------------------------+------------+-----------+------------------------+---------------------------------------------------------+
| id                        | estRows    | task      | access object          | operator info                                           |
+---------------------------+------------+-----------+------------------------+---------------------------------------------------------+
| HashAgg_11                | 1.00       | root      |                        | funcs:count(1)->Column#7                                |
| └─HashJoin_14             | 9659664.00 | root      |                        | CARTESIAN inner join, other cond:ne(test.t.b, test.t.b) |
|   ├─IndexReader_19(Build) | 3108.00    | root      |                        | index:IndexFullScan_18                                  |
|   │ └─IndexFullScan_18    | 3108.00    | cop[tikv] | table:t2, index:idx(b) | keep order:false                                        |
|   └─IndexReader_17(Probe) | 3108.00    | root      |                        | index:IndexFullScan_16                                  |
|     └─IndexFullScan_16    | 3108.00    | cop[tikv] | table:t1, index:idx(b) | keep order:false                                        |
+---------------------------+------------+-----------+------------------------+---------------------------------------------------------+

Feature Request

Add executor runtime info for explain for connection statement, such as below:

+---------------------------+------------+---------+-----------+------------------------+---------------------------------------------------------------------------------+---------------------------------------------------------+------------------+---------+
| id                        | estRows    | actRows | task      | access object          | execution info                                                                  | operator info                                           | memory           | disk    |
+---------------------------+------------+---------+-----------+------------------------+---------------------------------------------------------------------------------+---------------------------------------------------------+------------------+---------+
| HashAgg_11                | 1.00       | 1       | root      |                        | time:2.75491619s, loops:2, PartialConcurrency:4, FinalConcurrency:4             | funcs:count(1)->Column#7                                | 0 Bytes          | N/A     |
| └─HashJoin_14             | 9659664.00 | 9656556 | root      |                        | time:2.39850105s, loops:9432, Concurrency:5, probe collision:0, build:434.295µs | CARTESIAN inner join, other cond:ne(test.t.b, test.t.b) | 32.9375 KB       | 0 Bytes |
|   ├─IndexReader_19(Build) | 3108.00    | 3108    | root      |                        | time:690.901112ms, loops:5, rpc num: 1, rpc time:1.134724315s, proc keys:6190   | index:IndexFullScan_18                                  | 24.5615234375 KB | N/A     |
|   │ └─IndexFullScan_18    | 3108.00    | 3108    | cop[tikv] | table:t2, index:idx(b) | time:117ms, loops:8                                                             | keep order:false                                        | N/A              | N/A     |
|   └─IndexReader_17(Probe) | 3108.00    | 3108    | root      |                        | time:732.663444ms, loops:5, rpc num: 1, rpc time:1.134706548s, proc keys:6190   | index:IndexFullScan_16                                  | 24.5634765625 KB | N/A     |
|     └─IndexFullScan_16    | 3108.00    | 3108    | cop[tikv] | table:t1, index:idx(b) | time:117ms, loops:8                                                             | keep order:false                                        | N/A              | N/A     |
+---------------------------+------------+---------+-----------+------------------------+---------------------------------------------------------------------------------+---------------------------------------------------------+------------------+---------+

Actually the upper result it the result of explain analyze xxx.

Currently, TiDB doesn't collect the executor runtime information by default, but you can enable it by set the variable:

set tidb_enable_collect_execution_info=1;

Then TiDB will record the executor runtime information in the StatementContext.RuntimeStatsColl of the session. So you can add this runtime information in explain for connection statement.

Describe alternatives you've considered:

We can refer to the implementation of ExplainExec.generateExplainInfo, to avoid duplicate code.

Teachability, Documentation, Adoption, Migration Strategy:

• explain analyze

[zz-jason]

@crazycs520 Could you describe more about the use case of this feature?

[zz-jason]

Could we enable runtime statistics by default?

[hesper-guo]

/assign