Search Results
https://dev.mysql.com/doc/refman/8.4/en/where-optimization.html
The examples use SELECT statements, but the same optimizations apply for WHERE clauses in DELETE and UPDATE statements. MySQL quickly detects that some SELECT statements are impossible and returns no rows. A table that is used with a WHERE clause on ... This section discusses optimizations that can be made for processing WHERE ...
https://dev.mysql.com/doc/refman/8.4/en/optimizer-statistics.html
This histogram type is created when the number of distinct values in the column is less than or equal to the number of buckets specified in the ANALYZE TABLE statement that generated the histogram. This histogram type is created when the number of ... The column_statistics data dictionary table stores histogram statistics about column values, for use by the optimizer in constructing query execution ...
https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-metric-mysqlserver-handleractivity-category.html
Table 6.8 Handler Activity Metrics NameDescriptionCommit (Delta) The number of internal COMMIT statements. Prepare (Delta) The number of times the first entry in an index was read. Read First (Delta) The number of requests to read a row based on a ... Lists the Handler Activity metrics and provides a brief description of ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-buffer-page-table.html
IS_HASHED Whether a hash index has been built on this page. This column is applicable only to pages with a PAGE_TYPE value of INDEX. This can be the name of a clustered index or a secondary index. This column is applicable only to pages with a ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-params-ndbd.html
BuildIndexThreads: Number of threads to use for building ordered indexes during system or node restart. Setting this parameter to 0 disables multithreaded building of ordered indexes. DataMemory: Number of bytes on each data node allocated for ...
https://dev.mysql.com/doc/mysql-cluster-manager/8.4/en/mcm-attribute-tables-ndbd.html
BuildIndexThreads: Number of threads to use for building ordered indexes during system or node restart. Setting this parameter to 0 disables multithreaded building of ordered indexes. DataMemory: Number of bytes on each data node allocated for ...
https://dev.mysql.com/doc/mysql-monitor/8.0/en/admin-advisors-reference.html
It is used on master replication servers as a record of the statements to be sent to slave servers. The server writes information to this log when clients connect or disconnect, and it logs each SQL statement received from clients. As this SHOW ...
https://dev.mysql.com/doc/refman/8.4/en/alter-table-generated-columns.html
For stored columns, indexing changes are done in place, and expression changes are not done in place. Adding or dropping a secondary index on a virtual generated column is an in-place operation. For more information, see Section 15.1.20.9, ... ALTER ...
https://dev.mysql.com/doc/mysqld-version-reference/en/options-variables.html
The following table shows all the options and variables available in MySQL Server. Intr: The version or versions in which the item was introduced. Depr: The version or versions in which the item was deprecated. Removed: The version or versions in ...
https://dev.mysql.com/doc/heatwave/en/mys-hw-troubleshooting.html
Smaller, simpler queries, such as those that use indexes for quick lookups, often execute faster on the MySQL DB System. Alternatively, run the following statement: mysql> ALTER TABLE tbl_name SECONDARY_LOAD; The following error is reported if the ...Solution A: Your query contains an unsupported predicate, function, operator, or has encountered some other ...