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https://dev.mysql.com/doc/refman/8.0/en/no-matching-rows.html
If you have a complicated query that uses many tables but that returns no rows, you should use the following procedure to find out what is wrong: Test the query with EXPLAIN to check whether you can find something that is obviously wrong. Issue a ...Select only those columns that are used in the WHERE ...
https://dev.mysql.com/doc/refman/8.0/en/obtaining-plugin-information.html
Any that have a PLUGIN_LIBRARY value of NULL are built in and cannot be unloaded. Any that have a Library value of NULL are built in and cannot be unloaded. The mysql.plugin table shows which plugins have been registered with INSTALL PLUGIN. There ...
https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html
Conflicting hints In some cases hints can conflict, such as when JOIN_ORDER and JOIN_PREFIX have table orders that are impossible to apply at the same time: SELECT /*+ JOIN_ORDER(t1, t2) JOIN_PREFIX(t2, t1) */ ... These hints have no effect in MySQL ... One means of control over optimizer strategies is to set the optimizer_switch system variable (see Section 10.9.2, “Switchable ...
https://dev.mysql.com/doc/refman/8.0/en/optimizing-innodb-bulk-data-loading.html
If you have UNIQUE constraints on secondary keys, you can speed up table imports by temporarily turning off the uniqueness checks during the import session: SET unique_checks=0; ... If you have FOREIGN KEY constraints in your tables, you can speed ... These performance tips supplement the general guidelines for fast inserts in Section 10.2.5.1, “Optimizing INSERT ...
https://dev.mysql.com/doc/refman/8.0/en/optimizing-innodb-configuration-variables.html
Increasing the number of background threads for read or write operations, if you have a high-end I/O subsystem that is not fully utilized by the default values. InnoDB log files have often been kept small to avoid long startup times after a crash.
https://dev.mysql.com/doc/refman/8.0/en/optimizing-innodb-diskio.html
binlog_row_image If binary logs are on non-rotational storage and all tables have primary keys, consider setting this option to minimal to reduce logging. If you follow best practices for database design and tuning techniques for SQL operations, ...
https://dev.mysql.com/doc/refman/8.0/en/option-defaults-equals.html
You might try starting the server with --log-error my-errors, but this does not have the intended effect, as shown here: $> mysqld_safe --log-error my-errors & [1] 31357 $> 080111 22:53:31 mysqld_safe Logging to '/usr/local/mysql/var/tonfisk.err'.
https://dev.mysql.com/doc/refman/8.0/en/option-files.html
In an option file, you can have spaces around the = character, something that is not true on the command line. Note Any files to be found and included using the !includedir directive on Unix operating systems must have file names ending in .cnf. For ... Most MySQL programs can read startup options from option files (sometimes called configuration ...
https://dev.mysql.com/doc/refman/8.0/en/parenthesized-query-expressions.html
The maximum level of nesting supported is 63; this is after any simplifications or merges have been performed by the parser. parenthesized_query_expression: ( query_expression [order_by_clause] [limit_clause] ) [order_by_clause] [limit_clause] ...
https://dev.mysql.com/doc/refman/8.0/en/partitioning-limitations-partitioning-keys-unique-keys.html
The rule governing this relationship can be expressed as follows: All columns used in the partitioning expression for a partitioned table must be part of every unique key that the table may have. This section discusses the relationship of ...