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https://dev.mysql.com/doc/refman/8.4/en/mysql-shell-tutorial-python-documents-index.html
The final parameter indicates whether the field should require the NOT NULL constraint. Indexes are used to find documents with specific field values quickly. Without an index, MySQL must begin with the first document and then read through the ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-tips.html
This section provides information about techniques for more effective use of mysql and about mysql operational behavior. Input-Line Editing Disabling Interactive History Unicode Support on Windows Displaying Query Results Vertically Using ...
https://dev.mysql.com/doc/refman/8.4/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 ...
https://dev.mysql.com/doc/refman/8.4/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 ...
https://dev.mysql.com/doc/refman/8.4/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.
https://dev.mysql.com/doc/refman/8.4/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 ...
https://dev.mysql.com/doc/refman/8.4/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 ...
https://dev.mysql.com/doc/refman/8.4/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 ...
https://dev.mysql.com/doc/refman/8.4/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 ...
https://dev.mysql.com/doc/refman/8.4/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 ...