On Wed, Oct 22, 2008 at 3:29 AM, Matthieu Imbert <[EMAIL PROTECTED]> wrote: > Jeroen Vermeulen wrote: >> Matthieu Imbert wrote: >> >>> scenario 1 - parse the textual representation of all results of >>> requests to the database and convert textual timestamps to a binary >>> format that i choose among those ones (number of microseconds since >>> 2000-01-01, or a structure similar to pg_tm (but with >>> microsecond precision), or a time-format similar to one defined in >>> rfc1305, or something else) >>> >>> or >>> >>> scenario 2 - directly use pgsql binary timestamp format. I think the >>> latter is far more efficient. I'm new to postgresql, but from >>> what i understand, here are the conversions involved in both scenarios >>> (hopping that my ascii art won't be garbled by your mail >>> clients ;-) : >>> >>> >>> scenario 1: >>> .---------. .----------. .---------. .----------. .--------------. >>> .----------. .---------. >>> |timestamp| |pgsql | |timestamp| |pgsql | |timestamp | |my >>> | |my | >>> |storage |->|internal |->|storage |->|network |->|as >>> |->|timestamp |->|timestamp| >>> |in | |to | |in | |to | |textual | >>> |conversion| |format | >>> |database | |network | |network | |textual | |representation| >>> |routines | | | >>> |backend | |conversion| | | |conversion| | | | >>> | | | >>> | | |function | | | |function | | | | >>> | | | >>> '---------' '----------' '---------' '----------' '--------------' >>> '----------' '---------' >> >> I think this scenario has two boxes too many. Why would the backend >> convert to network representation before converting to text? >> >> >> Jeroen >> > > You mean that when results are asked in textual representation (the default), > data is sent on network directly as text?
yes. You should know that text/binary conversions rarely play a significant role in terms of performance. There are exceptions...large bytea columns, or enormous sets of integers. This is coming from a guy that co-wrote a library that allows you to pull data directly in binary. merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
