On Tue, May 23, 2006 at 02:55:03PM -0700, George Pavlov wrote: > Here is something that seems anomalous to me: when I set a boolean field > to FALSE performance is much better than when I set it to TRUE. Any > reason for FALSE to be favored over TRUE? > > Some details: > > vacuum analyze my_table; > update my_table set is_foo=FALSE where some_id = 47; > --142 rows affected, 8047 ms execution time. > vacuum analyze my_table; > update my_table set is_foo=TRUE where some_id = 47; > --142 rows affected, 48609 ms execution time. > > I have run these kinds of queries repeatedly and the timing above is > representative--the setting to FALSE case is about 6 times more > performant. The table my_table has about 105K rows and has many other > columns of various types. Thre is a trigger on the table, but it does > not do anything special based on this column's value. The some_id column > is indexed. This is on PG 8.1.3 on Linux. Are there any indexes containing is_foo? -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
