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https://dev.mysql.com/doc/refman/5.7/en/optimizing-innodb-queries.html
To tune queries for InnoDB tables, create an appropriate set of indexes on each table. Follow these guidelines for InnoDB indexes: Because each InnoDB table has a primary key (whether you request one or not), specify a set of primary key columns ...
https://dev.mysql.com/doc/refman/5.7/en/explain-for-connection.html
To obtain the execution plan for an explainable statement executing in a named connection, use this statement: EXPLAIN [options] FOR CONNECTION connection_id; EXPLAIN FOR CONNECTION returns the EXPLAIN information that is currently being used to ...
https://dev.mysql.com/doc/refman/5.7/en/tracing-example.html
Now we can examine the trace, whose first column (QUERY), containing the original statement to be traced, is shown here: SELECT * FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE\G *************************** 1. Next, for every table in the query, we ...row ...
https://dev.mysql.com/doc/refman/5.7/en/using-innodb-tables.html
.frm Files MySQL stores data dictionary information for tables in .frm files in database directories. InnoDB tables are created using the CREATE TABLE statement; for example: CREATE TABLE t1 (a INT, b CHAR (20), PRIMARY KEY (a)) ENGINE=InnoDB; The ...However, the ENGINE clause is useful if the CREATE TABLE statement is to be replayed on a different MySQL Server instance where the default storage engine is not InnoDB or is ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-performance-ro-txn.html
InnoDB can avoid the overhead associated with setting up the transaction ID (TRX_ID field) for transactions that are known to be read-only. In this case, attempting to make changes to the database (for InnoDB, MyISAM, or other types of tables) ...A ...Eliminating unnecessary transaction IDs reduces the size of internal data structures that are consulted each time a query or data change statement constructs a read ...
https://dev.mysql.com/doc/refman/5.7/en/myisam-storage-engine.html
Table 15.2 MyISAM Storage Engine Features Feature Support B-tree indexes Yes Backup/point-in-time recovery (Implemented in the server, rather than in the storage engine.) Yes Cluster database support No Clustered indexes No Compressed data Yes ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-table-descriptions.html
Tables in the performance_schema database can be grouped as follows: Setup tables. For example, to set the sizes of the wait event history tables, set performance_schema_events_waits_history_size and ...The events_waits_current table contains the ...These tables have the same structure as the current events tables, but contain more ...
https://dev.mysql.com/doc/refman/5.7/en/bit-functions.html
Table 12.17 Bit Functions and Operators Name Description & Bitwise AND >> Right shift << Left shift ^ Bitwise XOR BIT_COUNT() Return the number of bits that are set | Bitwise OR ~ Bitwise inversion The following list describes available bit ...
https://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html
The following relational comparison operators can be used to compare not only scalar operands, but row operands: = > < >= <= <> != The descriptions for those operators later in this section detail how they work with row operands. For additional ...
https://dev.mysql.com/doc/refman/5.7/en/create-logfile-group.html
The optional UNDO_BUFFER_SIZE parameter sets the size used by the UNDO buffer for the log file group; The default value for UNDO_BUFFER_SIZE is 8M (eight megabytes); this value cannot exceed the amount of system memory available. This includes any ...For rules covering the naming of log file groups, see Section 9.2, “Schema Object ... CREATE LOGFILE GROUP logfile_group ADD UNDOFILE 'undo_file' [INITIAL_SIZE [=] initial_size] [UNDO_BUFFER_SIZE [=] undo_buffer_size] [REDO_BUFFER_SIZE [=] redo_buffer_size] [NODEGROUP [=] nodegroup_id] [WAIT] [COMMENT [=] 'string'] ENGINE [=] engine_name This statement ...