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https://dev.mysql.com/doc/refman/8.0/en/sys-metrics.html
This view summarizes MySQL server metrics to show variable names, values, types, and whether they are enabled. The metric type determines the source from which the name is taken: For global status variables: The VARIABLE_NAME column of the ...
https://dev.mysql.com/doc/refman/8.0/en/thread-pool-tuning.html
Of chief importance is the number of thread groups in the thread pool, which can be set on server startup using the --thread-pool-size option; this cannot be changed at runtime. The recommendation initial setting for this system variable is the ...
https://dev.mysql.com/doc/refman/8.0/en/sys-schema-table-statistics-with-buffer.html
By default, rows are sorted by descending total wait time (tables with most contention first). fetch_latency The total wait time of timed read I/O events for the table. insert_latency The total wait time of timed insert I/O events for the table.
https://dev.mysql.com/doc/refman/8.0/en/innodb-consistent-read.html
A consistent read means that InnoDB uses multi-versioning to present to a query a snapshot of the database at a point in time. The query sees the changes made by transactions that committed before that point in time, and no changes made by later or ...The exception to this rule is that the query sees the changes made by earlier statements within the same ...
https://dev.mysql.com/doc/refman/8.0/en/optimizing-myisam-bulk-data-loading.html
For a MyISAM table, you can use concurrent inserts to add rows at the same time that SELECT statements are running, if there are no deleted rows in middle of the data file. Use the following procedure: Execute a FLUSH TABLES statement or a ... These ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-metadata-locks-table.html
MySQL uses metadata locking to manage concurrent access to database objects and to ensure data consistency; see Section 10.11.4, “Metadata Locking”. Lock requests that have timed out and are waiting for the requesting session's lock request to ...Metadata locking applies not just to tables, but also to schemas, stored programs (procedures, functions, triggers, scheduled events), tablespaces, user locks acquired with the GET_LOCK() function (see Section 14.14, “Locking Functions”), and locks acquired with the locking service described in Section 7.6.9.1, “The Locking ...
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_hosts_lost The number of times a row could ...Performance_schema_digest_lost The number of digest instances that could not be instrumented in the events_statements_summary_by_digest ...
https://dev.mysql.com/doc/refman/8.0/en/error-log-components.html
From MySQL 8.0.30, log_error_services also implicitly loads error log components if they are not already loaded. Whether the component can be listed multiple times in the log_error_services value. If log_sink_json is named multiple times in the ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-cmp-per-index-table.html
COMPRESS_TIME The total time in seconds used for compressing data in this index. Compressed InnoDB pages are uncompressed whenever compression fails, or the first time a compressed page is accessed in the buffer pool and the uncompressed page does ... The INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET tables provide status information on operations related to compressed InnoDB tables and indexes, with separate statistics for each combination of database, table, and index, to help you evaluate the performance and usefulness of compression for specific ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-partitions-table.html
UPDATE_TIME The time that the partition or subpartition was last modified. CHECK_TIME The last time that the table to which this partition or subpartition belongs was checked. For each such row: The SUBPARTITION_NAME, SUBPARTITION_ORDINAL_POSITION, ...Each row in this table corresponds to an individual partition or subpartition of a partitioned ...