PDF (US Ltr)
- 41.8Mb
PDF (A4)
- 41.9Mb
Man Pages (TGZ)
- 272.3Kb
Man Pages (Zip)
- 378.3Kb
Info (Gzip)
- 4.2Mb
Info (Zip)
- 4.2Mb
Search Results
https://dev.mysql.com/doc/refman/9.7/en/optimizing-queries-myisam.html
If you often need to calculate results such as counts based on information from a lot of rows, it may be preferable to introduce a new table and update the counter in real time. Some general tips for speeding up queries on MyISAM tables: To help ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-examples.html
The Performance Schema is a tool to help a DBA do performance tuning by taking real measurements instead of “wild guesses.” This section demonstrates some ways to use the Performance Schema for this purpose. The discussion here relies on the ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-memory-summary-tables.html
The real memory usage for this account could have been in the range from 11.5MB to 13.5MB. Operation counts help to understand or tune the overall pressure the server is putting on the memory allocator, which has an impact on performance. Allocating ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-processlist-table.html
For a replica SQL thread, the value is the number of seconds between the timestamp of the last replicated event and the real time of the replica host. The MySQL process list indicates the operations currently being performed by the set of threads ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-setup-instruments-table.html
At this point, the real statement type is unknown, the type will be refined after SQL parsing. (Events do not really have a “name,” but this provides a way to associate events with instruments.) ENABLED Whether the instrument is enabled. The ...
https://dev.mysql.com/doc/refman/9.7/en/user-variables.html
Assignment of decimal and real values does not preserve the precision or scale of the value. You can store a value in a user-defined variable in one statement and refer to it later in another statement. This enables you to pass values from one ...
https://dev.mysql.com/doc/refman/9.7/en/subquery-optimization-with-exists.html
This is a problem because many real world subqueries become very slow unless the equality can be pushed down. To help the query optimizer better execute your queries, use these suggestions: Declare a column as NOT NULL if it really is. Certain ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-timing.html
If a processor's cycle rate fluctuates, conversion from cycles to real-time units is subject to error. Events are collected by means of instrumentation added to the server source code. Instruments time events, which is how the Performance Schema ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-user-defined-functions-table.html
The value is one of int, decimal, real, char, or row. The user_defined_functions table contains a row for each loadable function registered automatically by a component or plugin, or manually by a CREATE FUNCTION statement. For information about ...
https://dev.mysql.com/doc/refman/9.7/en/precision-math-numbers.html
In MySQL, types that are synonymous with FLOAT or DOUBLE are DOUBLE PRECISION and REAL. The scope of precision math for exact-value operations includes the exact-value data types (integer and DECIMAL types) and exact-value numeric literals.