fix bug: MySQL CPU utilization spiked to 100%

[fengve]

What changed?

Removing unnecessary left joins serves no purpose other than wasting MySQL's CPU.
Adding an index to a FOR GROUP statement

Why?

Solve sql

SELECT STATUS , COUNT ( * ) FROM executions_visibility ev LEFT JOIN custom_search_attributes  USING ( namespace_id, run_id ) WHERE ( namespace_id= "32049b68-7872-4094-8e63-d0dd59896a83" ) AND TemporalNamespaceDivision IS NULL GROUP BY STATUS

mysql cpu occupied 100%

Why is the left join meaningless here?

1. COUNT(*) only counts the left table （executions_visibility）.
2. The filter condition 'TemporalNamespaceDivision IS NULL' also applies to the left table.
3. All connection keys are PK（namespace_id, run_id）, and there is no 1:N relationship.

How did you test it?

• built
• run locally and tested manually
• covered by existing tests
• added new unit test(s)
• added new functional test(s)

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