PDF (US Ltr)
- 35.1Mb
PDF (A4)
- 35.2Mb
Man Pages (TGZ)
- 256.4Kb
Man Pages (Zip)
- 361.2Kb
Info (Gzip)
- 3.4Mb
Info (Zip)
- 3.4Mb
Search Results
https://dev.mysql.com/doc/refman/5.7/en/group-by-optimization.html
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/innodb-buffer-pool.html
The buffer pool is an area in main memory where InnoDB caches table and index data as it is accessed. A table scan, performed for a mysqldump operation or a SELECT statement with no WHERE clause, for example, can bring a large amount of data into ...The buffer pool permits frequently used data to be accessed directly from memory, which speeds up ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-information-schema-understanding-innodb-locking.html
When a transaction updates a row in a table, or locks it with SELECT FOR UPDATE, InnoDB establishes a list or queue of locks on that row. Similarly, InnoDB maintains a list of locks on a table for table-level locks. If a second transaction wants to ...At any given time, a transaction may request a lock that is held by another transaction, in which case it is blocked by that other ...
https://dev.mysql.com/doc/refman/5.7/en/myisam-ftdump.html
It reads the MyISAM index file directly, so it must be run on the server host where the table is located. Before using myisam_ftdump, be sure to issue a FLUSH TABLES statement first if the server is running. Invoke myisam_ftdump like this: ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-log-events.html
Table 21.55 Events relating to NDB Cluster schema operations Event Priority Severity Level Description CreateSchemaObject 8 INFO Schema objected created AlterSchemaObject 8 INFO Schema object updated DropSchemaObject 8 INFO Schema object dropped ...
https://dev.mysql.com/doc/refman/5.7/en/nested-loop-joins.html
MySQL executes joins between tables using a nested-loop algorithm or variations on it. Nested-Loop Join Algorithm Block Nested-Loop Join Algorithm Nested-Loop Join Algorithm A simple nested-loop join (NLJ) algorithm reads rows from the first table ...For example, if 10 rows are read into a buffer and the buffer is passed to the next inner loop, each row read in the inner loop can be compared against all 10 rows in the ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-types.html
With this type of partitioning, a partition is selected based on the value returned by a user-defined expression that operates on column values in rows to be inserted into the table. When a new row is inserted into a partitioned table, it is these ... This section discusses the types of partitioning which are available in MySQL ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-status-variables.html
Performance Schema status variables have the following meanings: Performance_schema_accounts_lost The number of times a row could not be added to the accounts table because it was full. Performance_schema_digest_lost The number of digest instances ...This can be nonzero if the value of performance_schema_digests_size is too ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-timing.html
Performance Schema Timers Two Performance Schema tables provide timer information: performance_timers lists the available timers and their characteristics. For example, the standard gettimeofday() function can take hundreds of cycles, which is an ...
https://dev.mysql.com/doc/refman/5.7/en/resetting-permissions.html
Alternatively, on any platform, you can reset the password using the mysql client (but this approach is less secure): Stop the MySQL server if necessary, then restart it with the --skip-grant-tables option. If the ALTER USER statement fails to reset ...If you know the root password and want to change it, see Section 13.7.1.1, “ALTER USER Statement”, and Section 13.7.1.7, “SET PASSWORD ...