On 9 October 2011 04:35, Pavel Stehule <pavel.stehule@xxxxxxxxx> wrote: > 2011/10/8 Thom Brown <thom@xxxxxxxxx>: >> On 8 October 2011 21:13, Pavel Stehule <pavel.stehule@xxxxxxxxx> wrote: >>> 2011/10/8 Thom Brown <thom@xxxxxxxxx>: >>>> On 8 October 2011 19:47, Pavel Stehule <pavel.stehule@xxxxxxxxx> wrote: >>>>>>> I did it. It is strange, so your times are significantly slower than I >>>>>>> have. Have you enabled asserts? >>>>>> >>>>>> The table contains 15 million rows with column values randomly >>>>>> selected from the 1-350 range, with 60% within the 1-50 range, and >>>>>> asserts are enabled. >>>>>> >>>>> >>>>> Now I repeated tests on litlle bit wide table with 9 milion rows, but >>>>> without success. >>>>> >>>>> Try to disable asserts. I am not sure, but maybe there significantlly >>>>> change a speed. >>>> >>>> Okay, here you go. Results with debug_assertions = false: >>>> >>>> Index-only scan: 173.389 ms (78.442 ms) >>>> Index scan: 184239.399 ms (previously 164882.666 ms) >>>> Bitmap scan: 159354.261 ms (previously 154107.415 ms) >>>> Sequential scan: 134552.263 ms (previously 121296.999 ms) >>>> >>>> So no particularly significant difference, except with the index-only >>>> scan (which I repeated 3 times and it's about the same each time). >>> >>> what is size of table? >> >> 4884MB > > 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. -- Thom Brown Twitter: @darkixion IRC (freenode): dark_ixion Registered Linux user: #516935 EnterpriseDB UK: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
