MySQL Manual
5 MySQL Optimisation
- 5.2 Optimising
SELECTs and Other Queries- 5.2.1
EXPLAINSyntax (Get Information About aSELECT) - 5.2.2 Estimating Query Performance
- 5.2.3 Speed of
SELECTQueries - 5.2.4 How MySQL Optimises
WHEREClauses - 5.2.5 How MySQL Optimises
IS NULL - 5.2.6 How MySQL Optimises
DISTINCT - 5.2.7 How MySQL Optimises
LEFT JOINandRIGHT JOIN - 5.2.8 How MySQL Optimises
ORDER BY - 5.2.9 How MySQL Optimises
LIMIT - 5.2.10 Speed of
INSERTQueries - 5.2.11 Speed of
UPDATEQueries - 5.2.12 Speed of
DELETEQueries - 5.2.13 Other Optimisation Tips
- 5.2.1
5.2.12 Speed of DELETE Queries
If you want to delete all rows in the table, you should use
TRUNCATE TABLE table_name. See section 6.4.7 TRUNCATE Syntax.
The time to delete a record is exactly proportional to the number of indexes. To delete records more quickly, you can increase the size of the index cache. See section 5.5.2 Tuning Server Parameters.
User Comments
| Posted by Piter on Friday May 17 2002, @6:24am | [Delete] [Edit] |
"delete from ... order by ... limit ..." is very
slow.
A much faster way is to "select from ... order
by ... limit ..." and then "delete from ...
where ..." using the results of the previous
select query.
