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 Here's how I set it up: create table stuff (id serial, a text, b int, c int, d text, e text, f int, g int, h text, thing int); insert into stuff (a,b,c,d,e,f,g,h,thing) select 'nfewiufn weoifn weiou fnwe fnoi weuoifn woeuifniunfeiwodnjnfdoewnfjienfjioe wneinrienrf',53424524,26575757,'fhdsouhfuisdhfiudshif sdhiuf iu hfius dhfiu sdiuf dsihfiusdhiufhdsiufhdsiu fhiuds fhiusd fiuds fidsf iuds fiu dsiuf sdhiu','dfoisdhjfojdsoifjdiosjfoidsjiofjds',52944234,5246463,'fdfidsjoifjdsoifjoidsjfodsjfd',ceil(random()*350) from generate_series(1,6000000); insert into stuff (a,b,c,d,e,f,g,h,thing) select 'nfewiufn weoifn weiou fnwe fnoi weuoifn woeuifniunfeiwodnjnfdoewnfjienfjioe wneinrienrf',53424524,26575757,'fhdsouhfuisdhfiudshif sdhiuf iu hfius dhfiu sdiuf dsihfiusdhiufhdsiufhdsiu fhiuds fhiusd fiuds fidsf iuds fiu dsiuf sdhiu','dfoisdhjfojdsoifjdiosjfoidsjiofjds',52944234,5246463,'fdfidsjoifjdsoifjoidsjfodsjfd',ceil(random()*50) from generate_series(1,9000000); create index idx_stuff_thing on stuff (thing); vacuum analyse stuff; Testing without all the extra columns in the table yields a similar result pattern. -- 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
