PDF (US Ltr)
- 35.1Mb
PDF (A4)
- 35.2Mb
Man Pages (TGZ)
- 255.8Kb
Man Pages (Zip)
- 360.8Kb
Info (Gzip)
- 3.4Mb
Info (Zip)
- 3.4Mb
Search Results
https://dev.mysql.com/doc/refman/5.7/en/optimizing-queries-myisam.html
For MyISAM tables that change frequently, try to avoid all variable-length columns (VARCHAR, BLOB, and TEXT). The table uses dynamic row format if it includes even a single variable-length column. The only cases where splitting up a table makes an ... Some general tips for speeding up queries on MyISAM tables: To help MySQL better optimize queries, use ANALYZE TABLE or run myisamchk --analyze on a table after it has been loaded with ...
https://dev.mysql.com/doc/refman/5.7/en/replication-features-invoked.html
For example, trying to replicate a loadable function with statement-based replication generates this warning because it currently cannot be determined by the MySQL server whether the function is deterministic. The ORIGINATOR column in the ...
https://dev.mysql.com/doc/refman/5.7/en/show-slave-hosts.html
Statement output includes this column only if the source server is started with the --show-slave-auth-info option. Statement output includes this column only if the source server is started with the --show-slave-auth-info option. A zero in this ...
https://dev.mysql.com/doc/refman/5.7/en/subquery-materialization.html
Materialization speeds up query execution by generating a subquery result as a temporary table, normally in memory. Assume that where_condition involves columns only from t2 and not t1 so that the subquery is noncorrelated. The optimizer uses ...
https://dev.mysql.com/doc/refman/5.7/en/subquery-optimization-with-exists.html
Table-condition generator: If the subquery is a join of several tables, the triggered condition is checked as soon as possible. In EXPLAIN output, the fallback shows up as Full scan on NULL key in the Extra column: mysql> EXPLAIN SELECT t1.col1, ...
https://dev.mysql.com/doc/refman/5.7/en/bnl-bka-optimization.html
Suppose that join buffer B1 is employed to join tables t1 and t2 and the result of this operation is joined with table t3 using join buffer B2: A regular join buffer contains columns from each join operand. If B2 is a regular join buffer, each row r ... In MySQL, a Batched Key Access (BKA) Join algorithm is available that uses both index access to the joined table and a join ...
https://dev.mysql.com/doc/refman/5.7/en/engine-condition-pushdown-optimization.html
This optimization improves the efficiency of direct comparisons between a nonindexed column and a constant. (An index access method would be more efficient and so would be chosen in preference to condition pushdown.) Engine condition pushdown ...In ...
https://dev.mysql.com/doc/refman/5.7/en/group-by-optimization.html
The most important preconditions for using indexes for GROUP BY are that all GROUP BY columns reference attributes from the same index, and that the index stores its keys in order (as is true, for example, for a BTREE index, but not for a HASH ...
https://dev.mysql.com/doc/refman/5.7/en/identifier-qualifiers.html
ON mydb.mytable ...; A column name may be given multiple qualifiers to indicate context in statements that reference it, as shown in the following table. Suppose that column c1 occurs only in table t1, c2 only in t2, and c in both t1 and t2. Suppose ...An unqualified name is permitted in contexts where interpretation of the name is ...
https://dev.mysql.com/doc/refman/5.7/en/known-issues.html
DISTINCT with ORDER BY does not work inside GROUP_CONCAT() if you do not use all and only those columns that are in the DISTINCT list. When inserting a big integer value (between 263 and 264−1) into a decimal or string column, it is inserted as a ... This section lists known issues in recent versions of ...