Bug #110804 sql as "select count(*) from table" can't be logged in the slow query log.

• Submitted: 25 Apr 2023 13:47
• Modified: 26 Apr 2023 23:00
• Reporter: Siliang Wu
• Status: Verified
• Category: MySQL Server: Logging
• Severity: S3 (Non-critical)
• Version: 8.0.32
• OS: Any
• CPU Architecture: Any

[25 Apr 2023 13:47] Siliang Wu

Description:
When the variable min_examined_row_limit is set as a number larger than 0.
A sql as "select count(*) from table_name" execute longer than long_query_time,
but the sql is not logged in the slow query log.

Because the rows_examined for "select count(*) from table_name" is 0. "select count(*) from table_name" will search the whole table, so the rows_examined shouldn't be zero.

How to repeat:
Set min_examined_row_limit larger than 0 such as 100.
Execute a query as "select count(*) from table_name" which take longer time than long_query_time.
The sql won't be logged in the slow query log.

Suggested fix:
The rows_examined for the query "select count(*) from table_name" should not be calculated as

[26 Apr 2023 23:00] MySQL Verification Team

Hi,

Thanks for the report, reproduced as described.