Re: Repeated Query is much slower in PostgreSQL8.2.4 than DB2 9.1

Hi Craig,

The log is really long, but I compared the result of "explain analyze"
for first and later executions, except for 3 "time=XXX" numbers, they
are identical.
I agree with you that PostgreSQL is doing different level of caching,
I just wonder if there is any way to speed up PostgreSQL in this
scenario, which is a wrong way perhaps.

Thank you.
Ning


On Wed, Jul 15, 2009 at 5:27 PM, Craig
Ringer<craig@postnewspapers.com.au> wrote:
> On Wed, 2009-07-15 at 12:10 +0900, ning wrote:
>
>> First execution: PostgreSQL 0.006277 seconds / DB2 0.009028 seconds
>> Second execution: PostgreSQL 0.005932 seconds / DB2 0.000332 seconds
>
> Actually, on second thoughts that looks a lot like DB2 is caching the
> query results and is just returning the cached results when you repeat
> the query.
>
> I'm not sure to what extent PostgreSQL is capable of result caching, but
> I'd be surprised if it could do as much as DB2.
>
> --
> Craig Ringer
>
>