create table a ( imgid int not null, parent int, imgtype char(3), img longtext, primary key (imgid), key searchkey (parent, imgid) ) type = innodb;
T1) select imgid, parent from a where parent = 10; returns 3357 rows in 0.08 sec. T2) select imgid, parent, imgtype from a where parent = 10; return 3357 rows in 8.32 sec.!!!
T7) After change the searchkey to (parent, imgid, imgtype), T1/T2, T3/T4 runs in almost same speed.
Anybody can explain my questions:
Q1- What cause the slow down, T2 vs T1 and T4 vs T3? Q2- Can I assume mysql pooly handled on large BLOB data, by comparing performance of T6 and T4?
Best Reguards.
Q1:
It's explained in the MySQL Documentation under Optimization - How MySQL Uses Indexes. See http://www.mysql.com/doc/en/MySQL_indexes.html and pay close attention to the 5th bullet. This explains the behavior you see from T7.
Q2: I have no answer for you there, Sorry.
-- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
