Re: Cached Query Plans (was: global prepared statements)

"Jonah H. Harris" <jonah(dot)harris(at)gmail(dot)com> writes:
> On Sat, Apr 12, 2008 at 2:19 PM, Dawid Kuroczko <qnex42(at)gmail(dot)com> wrote:
>> There are other benefits as well. Oracle lets you see the statistics associated
>> with given plans. So you can see how many times given (cached) query was
>> executed, how much resources did it consume and do on.

> Yes, and it also uses that data at both the statement and column level
> to determine what needs more analysis to help build better plans in
> the future.

>> Right now the only way of getting such information from PostgreSQL is by
>> logging all queries and analyzing logs. The current_query column of
>> pg_stat_activity is useless as the (prepared) queries are usually so short
>> lived that you will see one execution out of thousands happening.

> Yes, this is worthless on large active databases. The logging
> overhead alone starts to affect performance.

But somehow, all that stuff with cached plans is free?

regards, tom lane