Maintenance operations.
REPAIR
For a table marked as crashed, usually after an interrupted write or a full disk.
phpMyAdmin: select the table, choose Repair table from the operations dropdown.
This resolves most cases without data loss.
If repair fails, restore from backup.
OPTIMISE
After large deletions, tables retain the space the deleted rows occupied.
Optimising reclaims it and can improve performance.
Select tables and choose Optimize table.
WHEN TO OPTIMISE
After clearing bloat: revisions, transients, spam, old logs.
Not routinely. On most tables it achieves little.
ANALYSE
Updates the statistics the query planner uses to choose how to run queries.
Occasionally helps a query that has become slow on a grown table.
BEFORE ANY OF THESE
Back up. These operations are generally safe and generally is not always.
ON LARGE TABLES
Optimising locks the table while it runs. On a busy site, do it at a quiet time.
IF CORRUPTION RECURS
Check disk space first. Then open a ticket.
