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https://dev.mysql.com/doc/refman/8.4/en/order-by-optimization.html
This section describes when MySQL can use an index to satisfy an ORDER BY clause, the filesort operation used when an index cannot be used, and execution plan information available from the optimizer about ORDER BY. An ORDER BY with and without ...
https://dev.mysql.com/doc/internals/en/optimizer-order-by-clauses.html
In general, the optimizer will skip the sort procedure for the ORDER BY clause if it sees that the rows will be in order anyway. For the query: SELECT column1 FROM Table1 ORDER BY 'x'; the optimizer will throw out the ORDER BY clause. For the ...
https://dev.mysql.com/doc/internals/en/row-order-within-result-sets.html
Please keep in mind that the row order within a significant number of result sets depends on storage engine properties and in worst cases the current load (NDB!, partitioning?, parallel query?) on the testing box. Either use --sorted_result SELECT ...
https://dev.mysql.com/doc/ndbapi/en/mccj-clusterj-_query-ordering.html
Ordering 4.3.1.20.1 Synopsis public static final class Query.Ordering extends, Enum<Ordering> {// Public Static Fields public static final Ordering ASCENDING ; public static final Ordering DESCENDING ;// Public Static Methods public static Ordering ...
https://dev.mysql.com/doc/internals/en/event-data-for-specific-event-types.html
The low-order five bits are 1 to indicate an empty option (has a length of 0) or 0 to indicate a non-empty option (has a length of 1). This should does not cause inconsistencies in replication because the only important property of transaction ...
https://dev.mysql.com/doc/workbench/en/wb-performance-reports.html
With Sorting – Lists all normalized statements that have done sorts (access in the following priority order: sort_merge_passes, sort_scans, and sort_rows). Tables with Full Table Scans – Finds tables that are being accessed by full table scans, ... Performance schema based reports provide insight into the MySQL server operations through helpful high-level ...
https://dev.mysql.com/doc/internals/en/com-query-response.html
Image description If it is not a valid Protocol::LengthEncodedInteger it is either a ERR_Packet or a Protocol::LOCAL_INFILE_Request. Image description 14.6.4.1.1 Text Resultset A Text Resultset is a possible COM_QUERY Response. It is made up of two ...
https://dev.mysql.com/doc/connectors/en/connector-j-time-instants.html
Background A time instant is a specific moment on a time-line. A time instant is said to be preserved when it always refers to the same point in time when its value is being stored to or retrieved from a database, no matter what time zones the ...
https://dev.mysql.com/doc/refman/8.4/en/lock-order-tool.html
To enable detection of lock-acquisition deadlocks and enforcement that runtime execution is free of them, MySQL supports LOCK_ORDER tooling. This enables a lock-order dependency graph to be defined as part of server design, and server runtime ...
https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-performance-page-database-file-io.html
Table 5.2 Database File I/O By Host NameDescription 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 threads and are reported with a ...