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https://dev.mysql.com/doc/refman/8.4/en/adding-character-set.html
For each collation listed in the <charset> element for the character set in Index.xml, MYSET.xml must contain a <collation> element that defines the character ordering. For each <collation> element listed in the <charset> element for the character ... This section discusses the procedure for adding a character set to ...
https://dev.mysql.com/doc/refman/8.4/en/engine-condition-pushdown-optimization.html
This optimization improves the efficiency of direct comparisons between a nonindexed column and a constant. In such cases, the condition is “pushed down” to the storage engine for evaluation. This optimization can be used only by the NDB ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-check.html
It first checks all index entries for errors and then reads through all rows. It calculates a checksum for all key values in the rows and verifies that the checksum matches the checksum for the keys in the index tree. This may take a long time for a ... To check a MyISAM table, use the following commands: myisamchk tbl_name This finds 99.99% of all ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-crash-recovery.html
File Purpose tbl_name.MYD Data file tbl_name.MYI Index file Each of these three file types is subject to corruption in various ways, but problems occur most often in data files and index files. If you use --quick, myisamchk does not create a ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-shell-tutorial-javascript-documents-modify.html
In this case, the index is 0, or the first element in the array. mysql-js> db.countryinfo.modify("Name = 'France'").arrayInsert("$.Airports[0]", "CDG") To delete an element from the array, you must pass to the arrayDelete() method the index of the ... You can use the modify() method to update one or more documents in a ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-shell-tutorial-python-documents-modify.html
In this case, the index is 0, or the first element in the array. mysql-py> db.countryinfo.modify("Name = 'France'").array_insert("$.Airports[0]", "CDG") To delete an element from the array, you must pass to the array_delete() method the index of the ... You can use the modify() method to update one or more documents in a ...
https://dev.mysql.com/doc/refman/8.4/en/online-ddl-memory-management.html
Online DDL operations that create or rebuild secondary indexes allocate temporary buffers during different phases of index creation. Defining an appropriate buffer size limit avoids potential out of memory errors for online DDL operations that ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-mutex-instances-table.html
The mutex_instances table has these indexes: Primary key on (OBJECT_INSTANCE_BEGIN) Index on (NAME) Index on (LOCKED_BY_THREAD_ID) TRUNCATE TABLE is not permitted for the mutex_instances table. The mutex_instances table lists all the mutexes seen ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-rwlock-instances-table.html
The rwlock_instances table has these indexes: Primary key on (OBJECT_INSTANCE_BEGIN) Index on (NAME) Index on (WRITE_LOCKED_BY_THREAD_ID) TRUNCATE TABLE is not permitted for the rwlock_instances table. The rwlock_instances table lists all the ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-handles-table.html
The table_handles table has these indexes: Primary key on (OBJECT_INSTANCE_BEGIN) Index on (OBJECT_TYPE, OBJECT_SCHEMA, OBJECT_NAME) Index on (OWNER_THREAD_ID, OWNER_EVENT_ID) TRUNCATE TABLE is not permitted for the table_handles table. The ...