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https://dev.mysql.com/doc/refman/8.0/en/innodb-next-key-locking.html
The so-called phantom problem occurs within a transaction when the same query produces different sets of rows at different times. For example, if a SELECT is executed twice, but returns a row the second time that was not returned the first time, ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-compression-background.html
An InnoDB table created with ROW_FORMAT=COMPRESSED can use a smaller page size on disk than the configured innodb_page_size value. But if you specify a value that is too small, there is additional overhead to reorganize the pages when data values ...
https://dev.mysql.com/doc/refman/8.0/en/thread-pool-tuning.html
You should bear in mind that the overhead of the connection polling operation for each thread group increases when using smaller values for the thread pool size with larger values for thread_pool_query_threads_per_group. Of chief importance is the ... This section provides guidelines on determining the best configuration for thread pool performance, as measured using a metric such as transactions per ...
https://dev.mysql.com/doc/refman/8.0/en/table-cache.html
For example, for 200 concurrent running connections, specify a table cache size of at least 200 * N, where N is the maximum number of tables per join in any of the queries which you execute. If table_open_cache is set too high, MySQL may run out of ... When you execute a mysqladmin status command, you should see something like this: Uptime: 426 Running threads: 1 Questions: 11082 Reloads: 1 Open tables: 12 The Open tables value of 12 can be somewhat puzzling if you have fewer than 12 ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-programs-ndb-select-all.html
ndb_select_all prints all rows from an NDB table to stdout. --gci Adds a GCI column to the output showing the global checkpoint at which each row was last updated. --gci64 Adds a ROW$GCI64 column to the output showing the global checkpoint at which ...Usage ndb_select_all -c connection_string tbl_name -d db_name [> file_name] Options that can be used with ndb_select_all are shown in the following ...
https://dev.mysql.com/doc/refman/8.0/en/replication-solutions-rbr-monitoring.html
The current progress of the replication applier (SQL) thread when using row-based replication is monitored through Performance Schema instrument stages, enabling you to track the processing of operations and check the amount of work completed and ...When these Performance Schema instrument stages are enabled the events_stages_current table shows stages for applier threads and their ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-programs-ndb-select-count.html
ndb_select_count prints the number of rows in one or more NDB tables. You can obtain row counts from multiple tables in the same database by listing the table names separated by spaces when invoking this command, as shown under Sample Output. With ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-data-node-memory-management.html
The size of the global shared memory for these resources is controlled by the SharedGlobalMemory configuration parameter (default: 128 MB). DataMemory is where records are stored, including hash indexes (approximately 15 bytes per row), ordered ...
https://dev.mysql.com/doc/refman/8.0/en/deleting-from-related-tables.html
If the total length of the DELETE statement for related_table is more than the default value of the max_allowed_packet system variable, you should split it into smaller parts and execute multiple DELETE statements. You probably get the fastest ...
https://dev.mysql.com/doc/refman/8.0/en/memory-storage-engine.html
However, the two types of tables differ in that MEMORY tables are not subject to storage conversion, whereas internal temporary tables are: If an internal temporary table becomes too large, the server automatically converts it to on-disk storage, as ...NDB Cluster offers the same features as the MEMORY engine with higher performance levels, and provides additional features not available with MEMORY: Row-level locking and multiple-thread operation for low contention between ...