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https://dev.mysql.com/doc/refman/8.0/en/sys-host-summary-by-file-io.html
The host_summary_by_file_io and x$host_summary_by_file_io views have these columns: host The host from which the client connected. Rows for which the HOST column in the underlying Performance Schema table is NULL are assumed to be for background ...
https://dev.mysql.com/doc/refman/8.0/en/sys-user-summary-by-file-io.html
The user_summary_by_file_io and x$user_summary_by_file_io views have these columns: user The client user name. Rows for which the USER column in the underlying Performance Schema table is NULL are assumed to be for background threads and are ...By ...
https://dev.mysql.com/doc/refman/8.0/en/sys-schema-table-statistics-with-buffer.html
update_latency The total wait time of timed update I/O events for the table. By default, rows are sorted by descending total wait time (tables with most contention first). The schema_table_statistics_with_buffer and ... These views summarize table ...
https://dev.mysql.com/doc/refman/8.0/en/sys-statement-analysis.html
The statement_analysis and x$statement_analysis views have these columns: query The normalized statement string. total_latency The total wait time of timed occurrences of the statement. max_latency The maximum single wait time of timed occurrences ...db The default database for the statement, or NULL if there is ...
https://dev.mysql.com/doc/refman/8.0/en/constant-folding-optimization.html
Comparisons between constants and column values in which the constant value is out of range or of the wrong type with respect to the column type are now handled once during query optimization rather row-by-row than during execution. The comparisons ...Consider the table created by the following statement: CREATE TABLE t (c TINYINT UNSIGNED NOT NULL); The WHERE condition in the query SELECT * FROM t WHERE c < 256 contains the integral constant 256 which is out of range for a TINYINT UNSIGNED ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-metrics-table.html
(The _RESET columns act like the lap counter on a stopwatch: you can measure the activity during some time interval, while the cumulative figures are still available in COUNT, MAX_COUNT, and so on.) MAX_COUNT_RESET The maximum counter value since it ...With more detailed queries, you can diagnose issues such as performance bottlenecks, resource shortages, and application ... The INNODB_METRICS table provides a ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-space-requirements.html
If the operation takes a long time and concurrent DML modifies the table so much that the size of the temporary log file exceeds the value of innodb_online_alter_log_max_size, the online DDL operation fails with a DB_ONLINE_LOG_TOO_BIG error, and ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-programs-ndb-error-reporter.html
The archive is named ndb_error_report_YYYYMMDDhhmmss.tar.bz2, where YYYYMMDDhhmmss is a datetime string. ndb_error_reporter also accepts the options listed here: --connection-timeout=timeout Command-Line Format --connection-timeout=# Type Integer ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-mutex-instances-table.html
The work performed while holding a mutex is said to be in a “critical section,” and multiple queries do execute this critical section in a serialized way (one at a time), which is a potential bottleneck. When a thread succeeds in locking a ...A ... The mutex_instances table lists all the mutexes seen by the Performance Schema while the server ...
https://dev.mysql.com/doc/refman/8.0/en/x-plugin-system-monitoring.html
Issue: mysql-py> \sql SELECT NAME, ENABLED, TIMED FROM performance_schema.setup_instruments WHERE NAME LIKE 'statement/%' AND NOT (ENABLED and TIMED) If this statement reports at least one row, you need to enable the instruments. When you execute a ... For general X Plugin monitoring, use the status variables that it ...