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https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-objects-table.html
For existing rows, only the ENABLED and TIMED columns can be modified, by users with the UPDATE privilege on the table. The setup_objects table has these columns: OBJECT_TYPE The type of object to instrument. The setup_objects table controls ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-status-variable-summary-tables.html
Each status variable summary table has one or more grouping columns to indicate how the table aggregates status values: status_by_account has USER, HOST, and VARIABLE_NAME columns to summarize status variables by account. status_by_host has HOST and ... The Performance Schema makes status variable information available in the tables described in Section 29.12.15, “Performance Schema Status Variable ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-status-variable-tables.html
For example: SELECT EVENT_NAME, COUNT_STAR FROM performance_schema.events_statements_summary_global_by_event_name WHERE EVENT_NAME LIKE 'statement/sql/%'; The global_status and session_status tables have these columns: VARIABLE_NAME The status ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-summary-tables.html
Each summary table has grouping columns that determine how to group the data to be aggregated, and summary columns that contain the aggregated values. Tables that summarize events in similar ways often have similar sets of summary columns and differ ... Summary tables provide aggregated information for terminated events over ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-system-variable-tables.html
The global_variables and session_variables tables have these columns: VARIABLE_NAME The system variable name. For session_variables, this column contains the variable value in effect for the current session. The global_variables and ... The MySQL ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-system-variables.html
The value applies to storage required for these columns: The SQL_TEXT column of the events_statements_current, events_statements_history, and events_statements_history_long statement event tables. Any bytes in excess of ...The Performance Schema ...
https://dev.mysql.com/doc/refman/8.4/en/show-processlist.html
row *************************** Id: 3123 User: stefan Host: localhost db: apollon Command: Query Time: 0 State: NULL Info: SHOW FULL PROCESSLIST SHOW PROCESSLIST output has these columns: Id The connection identifier. This is the same value ... SHOW ...
https://dev.mysql.com/doc/refman/8.4/en/stored-program-restrictions.html
Name Conflicts within Stored Routines The same identifier might be used for a routine parameter, a local variable, and a table column. The behavior that variables take precedence over table columns is nonstandard. However, the time shown in the ...
https://dev.mysql.com/doc/refman/8.4/en/where-optimization.html
If all columns in ORDER BY and GROUP BY clauses come from the same table, that table is preferred first when joining. If there is an ORDER BY clause and a different GROUP BY clause, or if the ORDER BY or GROUP BY contains columns from tables other ... This section discusses optimizations that can be made for processing WHERE ...
https://dev.mysql.com/doc/c-api/8.4/en/mysql-fetch-field.html
MYSQL_FIELD * mysql_fetch_field(MYSQL_RES *result) Description Returns the definition of one column of a result set as a MYSQL_FIELD structure. Call this function repeatedly to retrieve information about all columns in the result set. This should ...For metadata-optional connections, this function returns NULL when the resultset_metadata system variable is set to ...