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https://dev.mysql.com/doc/refman/8.4/en/index-extensions.html
Consider this table definition: CREATE TABLE t1 ( i1 INT NOT NULL DEFAULT 0, i2 INT NOT NULL DEFAULT 0, d DATE DEFAULT NULL, PRIMARY KEY (i1, i2), INDEX k_d (d) ) ENGINE = InnoDB; This table defines the primary key on columns (i1, i2). It also ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-files-table.html
The CREATION_TIME, LAST_UPDATE_TIME, and LAST_ACCESSED values are as reported by the operating system, and are not supplied by the NDB storage engine. This is the same as the value shown for the id column in the ndbinfo.dict_obj_info table and the ... The FILES table provides information about the files in which MySQL tablespace data is ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-read-only-instance.html
All queries read the latest version of a record, because update and deletes are not possible. Run the server with change buffering disabled (innodb_change_buffering=0) and do a slow shutdown. To enable read-only mode for an entire MySQL instance, ...
https://dev.mysql.com/doc/refman/8.4/en/json-validation-functions.html
This can be done using either of the functions detailed in this section, both of which take two arguments, a JSON schema, and a JSON document which is validated against the schema. JSON_SCHEMA_VALID() returns true if the document validates against ...Both functions handle null or invalid input as follows: If at least one of the arguments is NULL, the function returns ...
https://dev.mysql.com/doc/refman/8.4/en/load-xml.html
The tagname in the optional ROWS IDENTIFIED BY clause must also be given as a literal string, and must be surrounded by angle brackets (< and >). To write data from a table to an XML file, you can invoke the mysql client with the --xml and -e ...
https://dev.mysql.com/doc/refman/8.4/en/mrr-optimization.html
Reading rows using a range scan on a secondary index can result in many random disk accesses to the base table when the table is large and not stored in the storage engine's cache. With the Disk-Sweep Multi-Range Read (MRR) optimization, MySQL ...
https://dev.mysql.com/doc/refman/8.4/en/multiple-unix-servers.html
It is also possible to use the same server binary and start each invocation of it with different parameter values at runtime. For MySQL installation using an RPM distribution, server startup and shutdown is managed by systemd on several Linux ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-gr-memory-monitoring-ps-sample-queries.html
This section describes sample queries using the instruments and events for monitoring Group Replication memory usage. row *************************** EVENT_NAME: memory/group_rpl/memory_gr SUM(COUNT_ALLOC): 127 SUM(COUNT_FREE): 117 ...The memory ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-status-variable-tables.html
There are also summary tables that provide status variable information aggregated by account, host name, and user name. To obtain global and per-session statement execution counts, use the events_statements_summary_global_by_event_name and ... The ...
https://dev.mysql.com/doc/refman/8.4/en/replication-asynchronous-connection-failover-replica.html
The feature is designed for a group of senders and a group of receivers to keep synchronized with each other even when some members are temporarily unavailable. When the feature is active and correctly configured, if the primary that is replicating ... Asynchronous connection failover for replicas is activated automatically for a replication channel on a Group Replication primary when you set SOURCE_CONNECTION_AUTO_FAILOVER=1 in the CHANGE REPLICATION SOURCE TO statement for the ...