Hello,
I analize my mysql slow query log and see this:
" # Time: 040320 15:35:31 # [EMAIL PROTECTED]: maxpcco_autoresp[maxpcco_autoresp] @ localhost [] # Query_time: 5 Lock_time: 0 Rows_sent: 764220 Rows_examined: 764220 SET last_insert_id=764597; SELECT LAST_INSERT_ID() AS id FROM arp3_cam; # [EMAIL PROTECTED]: maxpcco_autoresp[maxpcco_autoresp] @ localhost [] # Query_time: 5 Lock_time: 0 Rows_sent: 764222 Rows_examined: 764222 SET last_insert_id=764599; SELECT LAST_INSERT_ID() AS id FROM arp3_cam; # Time: 040320 15:35:33 # [EMAIL PROTECTED]: maxpcco_autoresp[maxpcco_autoresp] @ localhost [] # Query_time: 7 Lock_time: 0 Rows_sent: 764221 Rows_examined: 764221 SET last_insert_id=764598; SELECT LAST_INSERT_ID() AS id FROM arp3_cam; # Time: 040320 15:35:34 # [EMAIL PROTECTED]: maxpcco_autoresp[maxpcco_autoresp] @ localhost [] # Query_time: 6 Lock_time: 0 Rows_sent: 764224 Rows_examined: 764224 SET last_insert_id=764601; SELECT LAST_INSERT_ID() AS id FROM arp3_cam; # [EMAIL PROTECTED]: maxpcco_autoresp[maxpcco_autoresp] @ localhost [] # Query_time: 8 Lock_time: 0 Rows_sent: 764223 Rows_examined: 764223 SET last_insert_id=764600; SELECT LAST_INSERT_ID() AS id FROM arp3_cam; "
Why these query are much slow to me?
SET last_insert_id=(number); SELECT LAST_INSERT_ID() AS id FROM arp3_cam;
Its necessary to examine all rows to get last id? Its possible to change anything to speed up this query?
There is. Use this query instead:
SELECT LAST_INSERT_ID();
There is no need to select LAST_INSERT_ID() for *every row in the table*.
The slow query log also contains queries that don't use any index at all to select rows from a table, which indicates a full scan. That's probably why you're seeing those queries in the log.
-- Paul DuBois, MySQL Documentation Team Madison, Wisconsin, USA MySQL AB, www.mysql.com
MySQL Users Conference: April 14-16, 2004 http://www.mysql.com/uc2004/
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