Pavel Stehule <pavel.stehule@xxxxxxxxx> writes: > 2011/10/9 Thom Brown <thom@xxxxxxxxx>: >> On 9 October 2011 04:35, Pavel Stehule <pavel.stehule@xxxxxxxxx> wrote: >>> It has a sense - index only scan  it is faster (and significantly >>> faster) on wider tables - or tables with strings where TOAST is not >>> active. Maybe there is a some issue because on thin tables is slower >>> (and I expect a should be faster everywhere). >> No, that's my point, I re-tested it on a table with just 2 int >> columns, and the results are roughly the same.  I added all the >> columns to make it expensive to fetch the  column being queried. > then I don't understand Are you sure you've remembered to vacuum the test table? I get results like yours (ie, no speed benefit for index-only scan) if the table doesn't have its visibility-map bits set. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
