… Extra 1 SIMPLE sol ALL (NULL) (NULL) (NULL) (NULL) 3 Using temporary; Using filesort 1 SIMPLE dom ALL (NULL) (NULL) (NULL) (NULL) 36 1…) (NULL) (NULL) (NULL) 99 Using where 1 SIMPLE cb eq_ref PRIMARY,cou_id PRIMARY 4 lds.ctf.ctf_cou_id 1 Using where
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
… will state that. Filesort is for indicating that filesort algorithm was used, while Disk_filesort means that sorting was done through temporary files. INNODB USAGE… DISTINCT c from sbtest where id between 501895 and 502895 order by c; or if InnoDB was not used: # Time: 071031 20…
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
… workaround is to modify statement to become SELECT with appropriate where clause. This however would not tell you full story, especially… catches possibly complex queries it can give you head ache. filesort, using temporary are always in the first line So it is impossible…
Post: The MySQL optimizer, the OS cache, and sequential versus random I/O
April 28, 2008 By 17 Comments
… the WHERE clause. Here’s the query plan initially. *************************** 1. row *************************** table: dim1 type: range key_len: 195 rows: 18790 Extra: Using where; Using temporary; Using filesort *************************** 2. row *************************** table: fact type: ref key_len: 4 rows: 606 Extra: Using where *************************** 3. row *************************** table: dim2…
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
… to have the patched MySQL installed in the system. Locate where the original mysqld binary is with: (garfield:~/work/mysql-5… it will depend on many factors such as storage engines used (InnoDB will take significantly longer to close than MyISAM), database… to get only those which use on-disk temporary storage for intermediate results “tmp_table_on_disk,filesort_on_disk†would be…
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
… management required or server does everything itself. Especially when using a CMS where DB structure is prepdefined A: MySQL Server will not… WHERE A=5 ORDER BY B will use index (A,B) for sorting optimization, for more complicated conditions you will need to use… mysql use index for group by? A: If you have Index on the column MySQL can avoid temporary table or filesort for group…
Post: Modeling MySQL Capacity by Measuring Resource Consumptions
March 8, 2011 By 1 Comment
…as network IO or memory to store temporary table, but let us ignore them for … unlikely to help. One helpful way to use this information is to compare systems with…0 0 0 0 0 0 # Boolean: # Filesort 0% yes, 99% no # Full scan 0% yes… which are in 100us range are ones where no IO needed to happen so such…
Comment: How to find wrong indexing with glance view
August 23, 2008 By 27 Comments
I was describing myspace’s search referenced by Nachos where country (sorry, it’s not city) is mandatory. Anyway, condition … be filesort and not necessary temporary table as we select from one table. To solve sorting issue on big sets, people can use pre-explain. Then decide either use hint to force ordered access or access based…
