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https://dev.mysql.com/doc/refman/8.4/en/innodb-online-ddl-operations.html
Concurrent queries are permitted with ALGORITHM=COPY for tables partitioned by HASH or LIST, as MySQL copies the data while holding a shared lock. Online support details, syntax examples, and usage notes for DDL operations are provided under the ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-preload-buffer-pool.html
After restarting a busy server, there is typically a warmup period with steadily increasing throughput, as disk pages that were in the buffer pool are brought back into memory (as the same data is queried, updated, and so on). To reduce the warmup ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-tablespace-autoextend-size.html
By default, when a file-per-table or general tablespace requires additional space, the tablespace is extended incrementally according to the following rules: If the tablespace is less than an extent in size, it is extended one page at a time. If ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-temporary-tablespace.html
InnoDB uses session temporary tablespaces and a global temporary tablespace. Session Temporary Tablespaces Session temporary tablespaces store user-created temporary tables and internal temporary tables created by the optimizer when InnoDB is ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-troubleshooting-datadict.html
Information about table definitions is stored in the InnoDB data dictionary. If you move data files around, dictionary data can become inconsistent. If a data dictionary corruption or consistency issue prevents you from starting InnoDB, see Section ...
https://dev.mysql.com/doc/refman/8.4/en/is-null-optimization.html
MySQL can also optimize the combination col_name = expr OR col_name IS NULL, a form that is common in resolved subqueries. MySQL can perform the same optimization on col_name IS NULL that it can use for col_name = constant_value. For example, MySQL ...
https://dev.mysql.com/doc/refman/8.4/en/key-cache-restructuring.html
However, restructuring does not block queries that need to use indexes assigned to the cache. File system caching is not as efficient as using a key cache, so although queries execute, a slowdown can be anticipated. A key cache can be restructured ...
https://dev.mysql.com/doc/refman/8.4/en/locale-support.html
The locale indicated by the lc_time_names system variable controls the language used to display day and month names and abbreviations. This variable affects the output from the DATE_FORMAT(), DAYNAME(), and MONTHNAME() functions. The lc_time_names ...
https://dev.mysql.com/doc/refman/8.4/en/mathematical-functions.html
ABS(X) Returns the absolute value of X, or NULL if X is NULL. An implication of this is that ABS(-9223372036854775808) produces an error because the result cannot be stored in a signed BIGINT value. mysql> SELECT ABS(2); -> 2 mysql> SELECT ABS(-32); ...
https://dev.mysql.com/doc/refman/8.4/en/metadata-locking.html
Metadata contention increases the more that multiple queries attempt to access the same objects. MySQL uses metadata locking to manage concurrent access to database objects and to ensure data consistency. Metadata locking applies not just to ...