…。 the explain: type:index，Extra:Using index; Using temporary; Using filesort i am chinese, so my english is bad…..sorry….. THANKS.
Post: What does Using filesort mean in MySQL?
March 5, 2009 By 27 Comments
… work at Percona, and I asked you “what does Using filesort mean in EXPLAIN,” what would you say? I have asked… truth is, filesort is badly named. Anytime a sort can’t be performed from an index, it’s a filesort. It has nothing to do with files. Filesort should be called “sort.” It is…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…_join: No Tmp_table: Yes Disk_tmp_table: No # Filesort: Yes Disk_filesort: No Merge_passes: 0 QC_Hit tells whether query…_tmp_table will state that. Filesort is for indicating that filesort algorithm was used, while Disk_filesort means that sorting was done through…_join: No Tmp_table: No Disk_tmp_table: No # Filesort: No Disk_filesort: No Merge_passes: 0 # No InnoDB statistics available for…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… things like whether Query cache was used or not, if Filesort was used, whether tmp table was created in memory or…: No Tmp_table: No Tmp_table_on_disk: No # Filesort: No Filesort_on_disk: No Merge_passes: 0 # InnoDB_IO_r_ops… 0 0 0 0 0 0 0 # Boolean: # Filesort 4% yes, 95% no # Filesort on 0% yes, 99% no # Full scan 4…
Post: MySQL Optimizer and Innodb Primary Key
October 3, 2006 By 9 Comments
… the sense it would not be faster to do external filesort than to do lookups in primary key order: mysql> explain… effectively key on (a,id) which means MySQL could skip filesort if ordering is done by primary key: mysql> explain select… Extra: Using where; Using index; Using filesort 1 row in set (0.00 sec) Filesort should be avoided in this case which…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
… | ref | PRIMARY,k | k | 4 | const | 1 | Using temporary; Using filesort | | 1 | SIMPLE | t | ref | k | k | 4 | test.test.i… | ref | PRIMARY,k | k | 4 | const | 1 | Using temporary; Using filesort | | 1 | SIMPLE | t | ref | k | k | 4 | test.test.i… index will be likely selected even if it leads to filesort. The solution for this problem is ether extending your indexes…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 14 Comments
… | Using where; Using filesort | +—-+————-+——–+——-+—————+——+———+——+——-+—————————–+ 1 row in set (0.00 sec) We can however use UNION to avoid filesort of full table… | NULL | NULL | Using filesort | +—-+————–+————–+——+—————+——+———+——-+——-+—————-+ 4 rows in set (0.01 sec) In this case there is also filesort but it applied only…
Comment: What does Using filesort mean in MySQL?
March 15, 2012 By 27 Comments
… ORDER BY a LIMIT 1698, 1 This one uses filesort (Extra: Using filesort): EXPLAIN SELECT * FROM table1 ORDER BY a LIMIT 1699… that MySQL uses to determine whether to use index or filesort? On mysql manual I notice that the above query satisfies… to resolve the query. It cannot if you see Using filesort in the Extra column.
Post: Finding what Created_tmp_disk_tables with log_slow_filter
September 22, 2008 By 3 Comments
…, full_scan, full_join, tmp_table, tmp_table_on_disk, filesort, filesort_on_disk] So now all I had to do was set the filter to “tmp_table_on_disk,filesort_on_disk†and I would get only those which use…. SET GLOBAL log_slow_filter:= “tmp_table_on_disk,filesort_on_diskâ€; Wait a couple of minutes and then set…
Post: Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
… patching file sql-common/my_time.c patching file sql/filesort.cc patching file sql/log.cc patching file sql/log…, full_scan, full_join, tmp_table, tmp_table_on_disk, filesort, filesort_on_disk] It allows you to filter queries logged by… temporary storage for intermediate results “tmp_table_on_disk,filesort_on_disk†would be a proper flags set. To clear…
