infoschema, util/stmtsummary: enhance statements_summary.

[ClSlaid]

What problem does this PR solve?

Issue Number: close #24083

Problem Summary:

What is changed and how it works?

What's Changed:

• changed all files in util/stmtsummary
• record all evicted information by sum

before:

select * from `INFORMATION_SCHEMA`.`STATEMENTS_SUMMARY`;

output:

BEGIN_TIME	...	DIGEST	SCHEMA_NAME	...
2019-01-01 00:30	...	digest_2	schema_name_2	...
2019-01-01 00:30	...	digest_1	schema_name_1	...
2019-01-01 00:00	...	digest_0	schema_name_0	...

statement_summary table has a fixed size, some statement digests may get kicked by other digests, leading to lose of information.

This pull request will append a special row to the statement_summary, which would sum up those statement digests got evicted from statement_summary, so that all digests' information will be recorded.

Following MySQL's behavior, the row's DIGEST and SCHEMA_NAME match no record in the table, their value is <nil>.

BEGIN_TIME	...	DIGEST	SCHEMA_NAME	...
2019-01-01 00:30	...	digest_2	schema_name_2	...
2019-01-01 00:30	...	digest_1	schema_name_1	...
2019-01-01 00:00	...	digest_0	schema_name_0	...
2019-01-01 00:30	...	<nil>	<nil>	...

Special rows corresponding to each interval will also be append to statements_summary_history table.

How it Works:

• adjust stmtSummaryByDigestEvictedElement in evicted.go, added a class member to record details
• add and Mutex to stmtSummaryByDigestEvicted to prevent data racing.

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Under construction

Side effects

• Performance regression
  • Consumes more CPU
  • Consumes more MEM
• Breaking backward compatibility

Release note

• record all evicted statements information by sum.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: ce03218e9e9a880b7ea0b87403fc960f1e4e9696

[ClSlaid]

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[ClSlaid]

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