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05-16-2008, 01:42 PM
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 Re: Execution Plan Cost The read-only plan of the query (SELECT $1 > 5) is prepared, so there is not parsing or planning. Any insight into what operations account for the executor startup/shutdown time? Thanks a lot, Luis Vargas On May 8 2008, Tom Lane wrote: >Luis Vargas <Luis.Vargas@cl.cam.ac.uk> writes: >> At the backend, I'm measuring the cost of executing (via >> SPI_execute_plan) the read-only plan of a simple query with no reference >> to tables. E.g. simpleplan(int) AS SELECT $1 > 5 > >> Executing this plan via SPI_execute takes around 70% more time than >> directly executing the relevant operator function (int4gt) and using >> DatumGetBool. > >Only that much? I'd have expected it to be several hundred times >slower, considering that int4gt is an utterly trivial function and >executor startup/shutdown is a fairly heavyweight operation. > > regards, tom lane > -- ************************************************** ************************ PhD Research Student Room FE04, Computer Laboratory, University of Cambridge Office: +44 (0) 1223 763 776 Mobile: +44 (0) 7767 086 105 MSN Messenger: luis_herring@hotmail.com ************************************************** ************************ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers      |
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