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https://dev.mysql.com/doc/refman/5.7/en/execution-plan-information.html
A query on a huge table can be performed without reading all the rows; a join involving several tables can be performed without comparing every combination of rows. Depending on the details of your tables, columns, indexes, and the conditions in ...
https://dev.mysql.com/doc/refman/5.7/en/explain-extended.html
See Section 8.2.2.1, “Optimizing Subqueries, Derived Tables, and View References with Semijoin Transformations”. For SELECT statements, the EXPLAIN statement produces extra (“extended”) information that is not part of EXPLAIN output but can ...
https://dev.mysql.com/doc/refman/5.7/en/foreign-key-optimization.html
That way, each small table can have a primary key for fast lookups of its data, and you can query just the set of columns that you need using a join operation. If a table has many columns, and you query many different combinations of columns, it ...
https://dev.mysql.com/doc/refman/5.7/en/function-optimization.html
If a function is tagged nondeterministic, a reference to it in a WHERE clause is evaluated for every row (when selecting from one table) or combination of rows (when selecting from a multiple-table join). A function is nondeterministic if, given ...
https://dev.mysql.com/doc/refman/5.7/en/group-by-handling.html
SQL-92 and earlier does not permit queries for which the select list, HAVING condition, or ORDER BY list refer to nonaggregated columns that are not named in the GROUP BY clause. SQL:1999 and later permits such nonaggregates per optional feature ...
https://dev.mysql.com/doc/refman/5.7/en/group-by-modifiers.html
You cannot test them as NULL values in join conditions or the WHERE clause to determine which rows to select. The GROUP BY clause permits a WITH ROLLUP modifier that causes summary output to include extra rows that represent higher-level (that is, ...
https://dev.mysql.com/doc/refman/5.7/en/group-by-optimization.html
If the WHERE clause contains range predicates (see the discussion of the range join type in Section 8.8.1, “Optimizing Queries with EXPLAIN”), a Loose Index Scan looks up the first key of each group that satisfies the range conditions, and again ... The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where all rows from each group are consecutive, and then use this temporary table to discover groups and apply aggregate functions (if ...
https://dev.mysql.com/doc/refman/5.7/en/group-replication-background.html
Servers can leave and join the group and the view is updated accordingly. The most common way to create a fault-tolerant system is to resort to making components redundant, in other words the component can be removed and the system should continue ...
https://dev.mysql.com/doc/refman/5.7/en/group-replication-deploying-locally.html
Usually you want all members to be able to serve as seeds for members that are joining the group and have not got the transactions processed by the group. The most common way to deploy Group Replication is using multiple server instances, to ...
https://dev.mysql.com/doc/refman/5.7/en/group-replication-ip-address-permissions.html
When a replication group is reconfigured (for example, when a new primary is elected or a member joins or leaves), the group members re-establish connections between themselves. The Group Replication plugin has a configuration option to determine ...