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https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html

For the MERGE and NO_MERGE hints, these precedence rules apply: A hint takes precedence over any optimizer heuristic that is not a technical constraint. One means of control over optimizer strategies is to set the optimizer_switch system variable ...

10.5.7 Optimizing InnoDB DDL Operations

https://dev.mysql.com/doc/refman/8.0/en/optimizing-innodb-ddl-operations.html

Foreign key constraints can make a TRUNCATE statement work like a regular DELETE statement, in which case a sequence of commands like DROP TABLE and CREATE TABLE might be fastest. Many DDL operations on tables and indexes (CREATE, ALTER, and DROP ...

29.17 The Performance Schema Memory-Allocation Model

https://dev.mysql.com/doc/refman/8.0/en/performance-schema-memory-model.html

Memory used depends on the load actually seen, not the load estimated or explicitly configured for. As the Performance Schema collects data, memory is allocated in the corresponding buffer. The buffer size is unbounded, and may grow with the load.

29.12.2.3 The setup_instruments Table

https://dev.mysql.com/doc/refman/8.0/en/performance-schema-setup-instruments-table.html

Due to constraints on name lengths with respect to potentially large numbers of connections, connections are named simply connection. The setup_instruments table lists classes of instrumented objects for which events can be collected: mysql> SELECT ...

29.12.20.3 Statement Summary Tables

https://dev.mysql.com/doc/refman/8.0/en/performance-schema-statement-summary-tables.html

The row with DIGEST = NULL is maintained because Performance Schema tables have a maximum size due to memory constraints. The Performance Schema maintains tables for collecting current and recent statement events, and aggregates that information in ...

29.7 Performance Schema Status Monitoring

https://dev.mysql.com/doc/refman/8.0/en/performance-schema-status-monitoring.html

Names for these variables have several forms: Performance_schema_xxx_classes_lost indicates how many instruments of type xxx could not be loaded. Performance_schema_xxx_instances_lost indicates how many instances of object type xxx could not be ...

29.16 Performance Schema Status Variables

https://dev.mysql.com/doc/refman/8.0/en/performance-schema-status-variables.html

Performance Schema status variables have the following meanings: Performance_schema_accounts_lost The number of times a row could not be added to the accounts table because it was full. Performance_schema_digest_lost The number of digest instances ...

19.1.6.2 Replication Source Options and Variables

https://dev.mysql.com/doc/refman/8.0/en/replication-options-source.html

This section describes the server options and system variables that you can use on replication source servers. You can specify the options either on the command line or in an option file. On the source and each replica, you must set the server_id ...

15.2.13.1 SELECT ... INTO Statement

https://dev.mysql.com/doc/refman/8.0/en/select-into.html

There are also constraints on the use of INTO within UNION statements; see Section 15.2.18, “UNION Clause”. INTO form of SELECT enables a query result to be stored in variables or written to a file: SELECT ... Column and line terminators can be ...

5.3.4.2 Selecting Particular Rows

https://dev.mysql.com/doc/refman/8.0/en/selecting-rows.html

Instead, you're usually more interested in answering a particular question, in which case you specify some constraints on the information you want. As shown in the preceding section, it is easy to retrieve an entire table. But typically you don't ...

Displaying 121 to 130 of 138 total results