Richard Huxton wrote:
WITH ANY OF THIS QUERIES MSSQL TAKES NOT MUCH OF 7 SECONDS....
In which case they make a bad choice for showing PostgreSQL is faster
than MSSQL. Is this the only query you have, or are others giving you
problems too?
I think count(*) is about the weakest point in PG, but I don't think
there'll be a general solution available soon. As I'm sure someone has
mentioned, whatever else, PG needs to check the row for its visibility
information.
From the start of your email, you seem to suspect your configuration
needs some work. Once you are happy that your settings in general are
good, you can override some by issuing set statements before your query.
For example:
SET work_mem = 10000;
might well improve example #2 where you had a hash.
--
Richard Huxton
Archonet Ltd
Someone had suggested keeping a vector table with +1 and -1 for row
insertion and deletion and then running a cron to sum the vectors and
update a table so that you could select from that table to get the row
count. Perhaps some sort of SUM() on a column function.
Since this seems like a reasonable approach (or perhaps there may be yet
another better mechanism), cannot someone add this sort of functionality
to Postgresql to do behind the scenes?
-Mike
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