Search Results
https://dev.mysql.com/doc/refman/8.4/en/innodb-persistent-stats.html
The persistent optimizer statistics feature improves plan stability by storing statistics to disk and making them persistent across server restarts so that the optimizer is more likely to make consistent choices each time for a given query.
https://dev.mysql.com/doc/refman/8.4/en/memory-storage-engine.html
Despite the in-memory processing for MEMORY tables, they are not necessarily faster than InnoDB tables on a busy server, for general-purpose queries, or under a read/write workload. User-Created and Temporary Tables MEMORY table contents are stored ... The MEMORY storage engine (formerly known as HEAP) creates special-purpose tables with contents that are stored in ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-limitations-transactions.html
This issue does not occur for queries that use index or table scans, even against NDB tables having BLOB or TEXT columns. You can help minimize issues with shared read locks by avoiding queries that use unique key lookups that retrieve BLOB or TEXT ... A number of limitations exist in NDB Cluster with regard to the handling of ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-options-variables.html
Two additional sources of information about pushed join performance are available: The status variables Ndb_pushed_queries_defined, Ndb_pushed_queries_dropped, Ndb_pushed_queries_executed, and Ndb_pushed_reads. Setting ndb_row_checksum to 0 means ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-failover.html
In the event that the primary Cluster replication process fails, it is possible to switch over to the secondary replication channel. This means that the ndb_apply_status table contains information for the replica on this host as well as for any ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-indexes.html
Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. If the table has an index for the columns in question, MySQL ...
https://dev.mysql.com/doc/refman/8.4/en/mysqladmin.html
Questions The number of questions (queries) from clients since the server was started. Slow queries The number of queries that have taken more than long_query_time seconds. You can use it to check the server's configuration and current status, to ...
https://dev.mysql.com/doc/refman/8.4/en/no-matching-rows.html
If you have a complicated query that uses many tables but that returns no rows, you should use the following procedure to find out what is wrong: Test the query with EXPLAIN to check whether you can find something that is obviously wrong. Select ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-limitations-partitioning-keys-unique-keys.html
This section discusses the relationship of partitioning keys with primary keys and unique keys. The rule governing this relationship can be expressed as follows: All columns used in the partitioning expression for a partitioned table must be part ...
https://dev.mysql.com/doc/refman/8.4/en/privileges-provided.html
AUDIT_ABORT_EXEMPT Allows queries blocked by an “abort” item in the audit log filter. SKIP_QUERY_REWRITE Queries issued by a user with this privilege are not subject to being rewritten by the Rewriter plugin (see Section 7.6.4, “The Rewriter ... The privileges granted to a MySQL account determine which operations the account can ...