Contents
How do I update index statistics in MySQL?
2) ALTER TABLE DROP KEY -> ALTER TABLE ADD KEY
- To just update statistics you can use the already mentioned “ANALYZE TABLE”.
- If you experience performance degradation on write-heavy servers you might need to restart mysql.
Does MySQL automatically index primary key?
Yes, primary key is automatically indexed in MySQL because primary key, index, etc gets stored into B-trees. The primary key is implicitly indexed in InnoDB, MyISAM, and other engines.
Do I need index on foreign key?
MySQL requires that foreign key columns be indexed; if you create a table with a foreign key constraint but no index on a given column, an index is created. Information about foreign keys on InnoDB tables can also be found in the INNODB_FOREIGN and INNODB_FOREIGN_COLS tables, in the INFORMATION_SCHEMA database.
How to re index primary key of MySQL database?
1) create a new table and copy the existing data over. 2) add another autoincrement field to the existing table, then delete the original column. I did this in phpmyadmin by unchecking the A_I box (Auto Increment setting), clicking save, and then checking it again, and clicking save again.
When do I need to rebuild an InnoDB table?
If you need to rebuild an InnoDB table because a CHECK TABLE operation indicates that a table upgrade is required, use mysqldump to create a dump file and mysql to reload the file.
What’s the best way to rebuild a table in MySQL?
Dump and Reload Method If you are rebuilding tables because a different version of MySQL cannot handle them after a binary (in-place) upgrade or downgrade, you must use the dump-and-reload method. Dump the tables before upgrading or downgrading using your original version of MySQL. Then reload the tables after upgrading or downgrading.
How to repair a table in mysqlcheck command line?
mysqlcheck –repair provides command-line access to the REPAIR TABLE statement. This can be a more convenient means of repairing tables because you can use the –databases or –all-databases option to repair all tables in specific databases or all databases, respectively: