… require 1TB in size. Now to see this point of intersection, let’s review different workload (which actually is closer to…/local/Percona-Server-5.5.30-rel30.2-500.Linux.x86_64/lib/mysql/libjemalloc.so [mysqld] gdb datadir=/mnt/data/mysql #for SSD… = 10G myisam_repair_threads = 1 myisam_recover socket=/var/lib/mysql/mysql.sock user=root skip-grant-tables TokuDB-related options are…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
… loaded the values from MySQL 5.5.30 and MySQL 5.6.10 to the different tables and ran the query: mysql [localhost] {msandbox} (test) > select…/sandboxes/msb_5_5_30/data/mysq | /mnt/data/sandboxes/msb_5_6_10/data/mysq | | CHARACTER_SETS_DIR | /mnt/nfs/dist/mysql-5.5.30…_union=on,index_merge_intersection=on,engine_condition_pushdown=on 1 row in set (0.00 sec) mysql [localhost] {msandbox} (test) > select…
Post: The Optimization That (Often) Isn't: Index Merge Intersection
December 14, 2012 By 6 Comments
… choices but only one index actually used. To some extent, MySQL 5.0 and later changed this situation with the introduction of… intersect(user_type,status,parent_id); Using where; Using index; Using filesort At first glance, this might not look too bad. MySQL… adjust the optimizer_switch configuration setting and disable index_merge_intersection. It’s a dynamically-adjustable setting and can be modified…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 31 Comments
… intersect(i1,i2); Using where | +—-+————-+———+————-+—————+——-+———+——+——+————————————-+ 1 row in set (0.00 sec) As you can see in this case MySQL does the Intersection…for such queries. P.S The tests were done in MySQL 5.4.2
Post: SystemTap - DTrace for Linux ?
September 14, 2009 By 17 Comments
…, this case is maybe too simple, but basically you can intersect internal MySQL function and script (measure time, count of call, statistics) what you what. I did not figure out yet how to intersect… application, as you may know DTrace-probes were added into MySQL 5.4, so interesting how it works. I should mention that…
Comment: Adjusting Innodb for Memory resident workload
March 27, 2009 By 11 Comments
… a DBA, but I know a little bit more about MySQL than most of the people here, so fixing this was… queries that hurt performance badly, all of them with “using intersect” in “Extra” and “index_merge” in “type” EXPLAIN fields. Other… second. We using MySQL 5.0.27 with no patches (except maybe for OS vendor specific — it`s RHEL 5.0). Binary log…
Comment: How to find wrong indexing with glance view
August 23, 2008 By 27 Comments
…’, mysql can use either indexes built on multiple columns or intersection of multiple accesses by indexes. When we talk about index_merge_intersection, we should understand that mysql finds one…-union-to-implement-loose-index-scan-to-mysql/#comment-1695 2. http://dev.mysql.com/doc/refman/5.1/en/index-merge-intersection.html
Comment: Multi Column indexes vs Index Merge
June 1, 2010 By 31 Comments
… 7. 1 row IN SET (0.00 sec) 1. mysql [localhost] {msandbox} (test)> EXPLAIN SELECT avg… 5. | 1 | SIMPLE | idxtest | index_merge | i1,i2,combined | i2,i1 | 4,4 | NULL | 959 | USING intersect…
