expression: add header for tidb_decode_plan result (#18440)

[ti-srebot]

cherry-pick #18440 to release-4.0

---

What problem does this PR solve?

After #17573, TiDB will record runtime information in slow-log plan field. the tidb_decode_plan maybe output 8 fields when plan with runtime information. It's hard to know the filed means without a header/column_name.

This PR add header for tidb_decode_plan result, such as below:

> select tidb_decode_plan('2wLwlTAJNl84CTAJMQlmdW5jczpjb3VudCgxKS0+Q29sdW1uIzUwCTEJdGltZTo3NjYuMDk5NzZtcywgbG9vcHM6MiwgUGFydGlhbENvbmN1cnJlbmN5OjQsIEZpbmFsQ29uY3VycmVuY3k6NAkxMC43NDAwMDU0OTMxNjQwNjIgTUIJTi9BCjEJMV8xMQkwCTgwMDAJZXEoQwl7LDMxLCAwKQk3NjE0MBGDIDUuMzU5NjQ4bRWEODc2CTEuOTA5NjAzMTE4OAEdDDQ0IE0JWxgyCTExXzEyAeHwWzAwMDAJdGFibGU6U0xPV19RVUVSWSwgb25seSBzZWFyY2ggaW4gdGhlIGN1cnJlbnQgJ3RpZGItc2xvdy5sb2cnIGZpbGUJNzY0NjkJdGltZTo2NTEuODk5NDAzHY4kNwlOL0EJTi9BCg==');
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_decode_plan('2wLwlTAJNl84CTAJMQlmdW5jczpjb3VudCgxKS0+Q29sdW1uIzUwCTEJdGltZTo3NjYuMDk5NzZtcywgbG9vcHM6MiwgUGFydGlhbENvbmN1cnJlbmN5OjQsIEZpbmFsQ29uY3VycmVuY3k6NAkxMC43NDAwMDU0OTMxNjQwNjIgTUIJTi9BCjEJMV8xMQkwCTgwMDAJZXEoQwl7LDMxLCAwKQk3NjE0MBGDIDUuMzU5Nj |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|     id                     task    estRows    operator info                                                        actRows    execution info                                                         memory                   disk                               |
|     HashAgg_8              root    1          funcs:count(1)->Column#50                                            1          time:766.09976ms, loops:2, PartialConcurrency:4, FinalConcurrency:4    10.740005493164062 MB    N/A                                |
|     └─Selection_11         root    8000       eq(Column#31, 0)                                                     76140      time:765.359648ms, loops:76                                            1.9096031188964844 MB    N/A                                |
|       └─MemTableScan_12    root    10000      table:SLOW_QUERY, only search in the current 'tidb-slow.log' file    76469      time:651.899403ms, loops:77                                            N/A                      N/A                                |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

Before this PR, the result will be:

> select tidb_decode_plan('2wLwlTAJNl84CTAJMQlmdW5jczpjb3VudCgxKS0+Q29sdW1uIzUwCTEJdGltZTo3NjYuMDk5NzZtcywgbG9vcHM6MiwgUGFydGlhbENvbmN1cnJlbmN5OjQsIEZpbmFsQ29uY3VycmVuY3k6NAkxMC43NDAwMDU0OTMxNjQwNjIgTUIJTi9BCjEJMV8xMQkwCTgwMDAJZXEoQwl7LDMxLCAwKQk3NjE0MBGDIDUuMzU5NjQ4bRWEODc2CTEuOTA5NjAzMTE4OAEdDDQ0IE0JWxgyCTExXzEyAeHwWzAwMDAJdGFibGU6U0xPV19RVUVSWSwgb25seSBzZWFyY2ggaW4gdGhlIGN1cnJlbnQgJ3RpZGItc2xvdy5sb2cnIGZpbGUJNzY0NjkJdGltZTo2NTEuODk5NDAzHY4kNwlOL0EJTi9BCg==');
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_decode_plan('2wLwlTAJNl84CTAJMQlmdW5jczpjb3VudCgxKS0+Q29sdW1uIzUwCTEJdGltZTo3NjYuMDk5NzZtcywgbG9vcHM6MiwgUGFydGlhbENvbmN1cnJlbmN5OjQsIEZpbmFsQ29uY3VycmVuY3k6NAkxMC43NDAwMDU0OTMxNjQwNjIgTUIJTi9BCjEJMV8xMQkwCTgwMDAJZXEoQwl7LDMxLCAwKQk3NjE0MBGDIDUuMzU5Nj |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|     HashAgg_8              root    1        funcs:count(1)->Column#50                                            1        time:766.09976ms, loops:2, PartialConcurrency:4, FinalConcurrency:4    10.740005493164062 MB    N/A                                    |
|     └─Selection_11         root    8000     eq(Column#31, 0)                                                     76140    time:765.359648ms, loops:76                                            1.9096031188964844 MB    N/A                                    |
|       └─MemTableScan_12    root    10000    table:SLOW_QUERY, only search in the current 'tidb-slow.log' file    76469    time:651.899403ms, loops:77                                            N/A                      N/A                                    |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

What is changed and how it works?

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Unit test

Side effects

• Breaking backward compatibility

Release note

• Add a header for tidb_decode_plan result.

[ti-srebot]

/run-all-tests

[tangenta]

LGTM

[ti-srebot]

@tangenta,Thanks for your review.

[djshow832]

LGTM

[ti-srebot]

@djshow832,Thanks for your review.

[SunRunAway]

/merge

[ti-srebot]

/run-all-tests

[ti-srebot]

@ti-srebot merge failed.

[crazycs520]

/rebuild