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https://dev.mysql.com/doc/refman/5.7/en/query-issues.html
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https://dev.mysql.com/doc/refman/5.7/en/dba-dtrace-mysqld-ref.html
The query cache probes are best combined with a probe on the main query so that you can determine the differences in times between using or not using the query cache for specified queries. A high number of keycache reads across a range of queries ...
https://dev.mysql.com/doc/refman/5.7/en/glossary.html
If related data is being updated across multiple tables, queries see either all old values or all new values, not a mix of old and new values. MySQL monitors index searches for InnoDB tables, and if queries could benefit from a hash index, it builds ... These terms are commonly used in information about the MySQL database ...
https://dev.mysql.com/doc/refman/5.7/en/information-schema-optimization.html
Certain types of queries for INFORMATION_SCHEMA tables can be optimized to execute more quickly. Note Comparison behavior for database and table names in INFORMATION_SCHEMA queries might differ from what you expect. 1) Try to use constant lookup ...
https://dev.mysql.com/doc/refman/5.7/en/limit-optimization.html
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 data. MySQL sometimes optimizes a query that has a LIMIT row_count clause and no ...
https://dev.mysql.com/doc/refman/5.7/en/mysqldumpslow.html
The MySQL slow query log contains information about queries that take a long time to execute (see Section 5.4.5, “The Slow Query Log”). Normally, mysqldumpslow groups queries that are similar except for the particular values of number and ...
https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html
This prevents most The table tbl_name is full errors for SELECT operations that require a large temporary table, but also slows down queries for which in-memory tables would suffice. When using internal_tmp_disk_storage_engine=INNODB (the default), ... The MySQL server maintains many system variables that affect its ...
https://dev.mysql.com/doc/refman/5.7/en/execution-plan-information.html
Depending on the details of your tables, columns, indexes, and the conditions in your WHERE clause, the MySQL optimizer considers many techniques to efficiently perform the lookups involved in an SQL query. A query on a huge table can be performed ...
https://dev.mysql.com/doc/refman/5.7/en/controlling-optimizer.html
MySQL provides optimizer control through system variables that affect how query plans are evaluated, switchable optimizations, optimizer and index hints, and the optimizer cost model.
https://dev.mysql.com/doc/refman/5.7/en/estimating-performance.html
In most cases, you can estimate query performance by counting disk seeks. For small tables, you can usually find a row in one disk seek (because the index is probably cached). For bigger tables, you can estimate that, using B-tree indexes, you need ...