Re: Perl/DBI vs Native

Craig James <craig_james(at)emolecules(dot)com> writes:
> Valentin Bogdanov wrote:
>> I have ran quite a few tests comparing how long a query takes to
>> execute from Perl/DBI as compared to psql/pqlib. No matter how many
>> times I run the test the results were always the same.
>>
>> I run a SELECT all on a fairly big table and enabled the
>> log_min_duration_statement option. With psql postgres consistently
>> logs half a second while the exact same query executed with Perl/DBI
>> takes again consistently 2 seconds.

> The problem may be that your two tests are not equivalent. When Perl
> executes a statement, it copies the *entire* result set back to the
> client before it returns the first row.

Sure, but so does psql (unless you've turned on the magic FETCH_COUNT
setting). I think the theories about prepared versus literal statements
were more promising; but I don't know DBI well enough to know exactly
what it was sending to the server.

regards, tom lane