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https://dev.mysql.com/doc/refman/8.4/en/system-schema.html
They cannot be read with SELECT, do not appear in the output of SHOW TABLES, are not listed in the INFORMATION_SCHEMA.TABLES table, and so forth. For example, you cannot select from the mysql.schemata table directly: mysql> SELECT * FROM ...It ...
https://dev.mysql.com/doc/refman/8.4/en/telemetry-metrics-meter-metrics.html
For example, the select metric corresponds to the Com_select statement counter variable. errors_select Connection_errors_select ASYNC COUNTER The number of errors that occurred during calls to select() or poll() on the listening port. The following ...
https://dev.mysql.com/doc/refman/8.4/en/temporary-table-problems.html
For example, the following does not work: SELECT * FROM temp_table JOIN temp_table AS t2; The statement produces this error: ERROR 1137: Can't reopen table: 'temp_table' You can work around this issue if your query permits use of a common table ...
https://dev.mysql.com/doc/refman/8.4/en/union.html
query_expression_body UNION [ALL | DISTINCT] query_block [UNION [ALL | DISTINCT] query_expression_body] [...] query_expression_body: See Section 15.2.14, “Set Operations with UNION, INTERSECT, and EXCEPT” UNION combines the result from multiple ...
https://dev.mysql.com/doc/refman/8.4/en/use.html
The named database remains the default until the end of the session or another USE statement is issued: USE db1; SELECT COUNT(*) FROM mytable; # selects from db1.mytable USE db2; SELECT COUNT(*) FROM mytable; # selects from db2.mytable The database ... USE db_name The USE statement tells MySQL to use the named database as the default (current) database for subsequent ...
https://dev.mysql.com/doc/refman/8.4/en/using-spatial-indexes.html
The following query finds all objects that are in the given rectangle: mysql> SET @poly = -> 'Polygon((30000 15000, 31000 15000, 31000 16000, 30000 16000, 30000 15000))'; mysql> SELECT fid,ST_AsText(g) FROM geom WHERE -> ... The optimizer ...
https://dev.mysql.com/doc/refman/8.4/en/window-function-optimization.html
Window functions affect the strategies the optimizer considers: Derived table merging for a subquery is disabled if the subquery has window functions. Semijoins are not applicable to window function optimization because semijoins apply to ...
https://dev.mysql.com/doc/refman/8.4/en/x-plugin-system-monitoring.html
Issue: mysql-py> \sql SELECT enabled FROM performance_schema.setup_consumers WHERE NAME = 'events_statements_history' +---------+ | enabled | +---------+ | YES | +---------+ Check if all instruments report data to the consumer. Issue: mysql-py> \sql ... For general X Plugin monitoring, use the status variables that it ...
https://dev.mysql.com/doc/mysql-enterprise-backup/8.4/en/restore.partial.html
Table-Level Recovery (TLR) allows selected tables (or schemas) to be restored from a backup (be it a full backup, a partial backup, or a backup created using transportable tablespaces (TTS)) using the --include-tables and --exclude-tables options.
https://dev.mysql.com/doc/c-api/8.4/en/c-api-prepared-statement-interface-usage.html
If the statement is a SELECT or any other statement that produces a result set, call mysql_stmt_result_metadata() if it is desired to obtain the result set metadata. If you obtained a SELECT statement's result set metadata by calling ... To prepare ...