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https://dev.mysql.com/doc/refman/8.4/en/server-system-variables.html
end_markers_in_json Command-Line Format --end-markers-in-json[={OFF|ON}] System Variable end_markers_in_json Scope Global, Session Dynamic Yes SET_VAR Hint Applies Yes Type Boolean Default Value OFF Whether optimizer JSON output should add end ...
https://dev.mysql.com/doc/internals/en/optimizer-features-to-trace.html
Some features in the optimizer can be invoked many times during statement optimization and execution, and thus can make the trace grow beyond reason. They are: Greedy search: with a N-table join, this could explore factorial(N) plans Range ...
https://dev.mysql.com/doc/refman/8.4/en/function-optimization.html
For example, some optimizations may not be available, or more locking might be required. The behavior just described has implications for performance and replication: Because a nondeterministic function does not produce a constant value, the ...A ...
https://dev.mysql.com/doc/refman/8.4/en/mrr-optimization.html
With the Disk-Sweep Multi-Range Read (MRR) optimization, MySQL tries to reduce the number of random disk access for range scans by first scanning the index only and collecting the keys for the relevant rows. The Multi-Range Read optimization ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-optimization.html
To coalesce fragmented rows and eliminate wasted space that results from deleting or updating rows, run myisamchk in recovery mode: $> myisamchk -r tbl_name You can optimize a table in the same way by using the OPTIMIZE TABLE SQL statement.
https://dev.mysql.com/doc/refman/8.4/en/optimize-overview.html
Optimizing at the Hardware Level Any database application eventually hits hardware limits as the database becomes more and more busy. This time improves slowly with new disks and is very hard to optimize for a single table. The way to optimize seek ... Database performance depends on several factors at the database level, such as tables, queries, and configuration ...
https://dev.mysql.com/doc/refman/8.4/en/subquery-optimization.html
Note A limitation on UPDATE and DELETE statements that use a subquery to modify a single table is that the optimizer does not use semijoin or materialization subquery optimizations. As a workaround, try rewriting them as multiple-table UPDATE and ...
https://dev.mysql.com/doc/refman/8.4/en/window-function-optimization.html
Window functions affect the strategies the optimizer considers: Derived table merging for a subquery is disabled if the subquery has window functions. Semijoins are not applicable to window function optimization because semijoins apply to ...The ...
https://dev.mysql.com/doc/heatwave/en/mys-hw-limitations-index-optimizer-hints.html
MySQL attempts to enforce the FIRSTMATCH strategy and ignores all other semijoin strategies specified explicitly as subquery optimizer hints. However, MySQL may still select the DUPSWEEDOUT semijoin strategy during JOIN order optimization, even if ...A plan that uses the DUPSWEEDOUT semijoin strategy would produce incorrect results if executed on ...
https://dev.mysql.com/doc/refman/8.4/en/limit-optimization.html
MySQL sometimes optimizes a query that has a LIMIT row_count clause and no HAVING clause: If you select only a few rows with LIMIT, MySQL uses indexes in some cases when normally it would prefer to do a full table scan. If an index is not used for ... If you need only a specified number of rows from a result set, use a LIMIT clause in the query, rather than fetching the whole result set and throwing away the extra ...