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https://dev.mysql.com/doc/refman/8.4/en/innodb-limits.html
If you reduce the InnoDB page size to 8KB or 4KB by specifying the innodb_page_size option when creating the MySQL instance, the maximum length of the index key is lowered proportionally, based on the limit of 3072 bytes for a 16KB page size. This ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-online-ddl-single-multi.html
Before the introduction of online DDL, it was common practice to combine many DDL operations into a single ALTER TABLE statement. Because each ALTER TABLE statement involved copying and rebuilding the table, it was more efficient to make several ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-performance-optimizer-statistics.html
You can use the STATS_PERSISTENT, STATS_AUTO_RECALC, and STATS_SAMPLE_PAGES clauses with CREATE TABLE and ALTER TABLE statements to configure optimizer statistics for individual tables. This section describes how to configure persistent and ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-physical-structure.html
InnoDB performs a bulk load when creating or rebuilding B-tree indexes. This method of index creation is known as a sorted index build. With the exception of spatial indexes, InnoDB indexes are B-tree data structures. Spatial indexes use R-trees, ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-recovery.html
In some cases of database corruption, it is enough to dump, drop, and re-create one or a few corrupt tables. To achieve point-in-time recovery after restoring a backup, you can apply changes from the binary log that occurred after the backup was ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-table-compression.html
Table compression is enabled using the ROW_FORMAT=COMPRESSED attribute with CREATE TABLE or ALTER TABLE. This section describes InnoDB table compression, which is supported with InnoDB tables that reside in file_per_table tablespaces or general ...
https://dev.mysql.com/doc/refman/8.4/en/key-space.html
In MyISAM tables, you can also prefix compress numbers by specifying the PACK_KEYS=1 table option when you create the table. You can roughly calculate the size for the index file as (key_length+4)/0.67, summed over all keys. This is for the worst ...
https://dev.mysql.com/doc/refman/8.4/en/known-issues.html
Creation of a table of type MERGE does not check whether the underlying tables are compatible types. This section lists known issues in recent versions of MySQL. For information about platform-specific issues, see the installation and debugging ...
https://dev.mysql.com/doc/refman/8.4/en/loop.html
Example: CREATE PROCEDURE doiterate(p1 INT) BEGIN label1: LOOP SET p1 = p1 + 1; IF p1 < 10 THEN ITERATE label1; END IF; LEAVE label1; END LOOP label1; SET @x = p1; END; . [begin_label:] LOOP statement_list END LOOP [end_label] LOOP implements a ...
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); ...