Re: General key issues when comparing performance between PostgreSQL and oracle

On Tue, Jul 16, 2013 at 10:51 AM, Brian Fehrle
<brianf(at)consistentstate(dot)com> wrote:
> Hi all (Hopefully this is the correct mailing list for this).
>
> I'm working on performance tuning a host of queries on PostgreSQL 9.2 from
> an application, each query having its own issues and fixes, however from
> what I understand this application runs the exact same queries on the exact
> same data in half the time on oracle and SQL server.
>
> Are there any known differences between the database systems in terms of
> query planners or general operations (sorting, unions) that are notable
> different between the systems that would make postgres slow down when
> executing the exact same queries?
>
> It's worth noting that the queries are not that good, they have issues with
> bad sub-selects, Cartesian products, and what looks like bad query design in
> general, so the blame isn't completely with the database being slow, but I
> wonder what makes oracle preform better when given not-so-great queries?
>
> I know this is rather general and high level, but any tips or experience
> anyone has would be appreciated.

Here's the thing. The Postgres team is small, and they have to choose
wisely what to work on. So, do they work on making everything else
better, faster and more reliable, or do they dedicate precious man
hours to making bad queries run well?

Fact is that if the query can be made better, then you get to do that.
After optimizing the query, if you find a corner case where
postgresql's query planner is making a bad decision or where some new
db method would make it faster then it's time to appeal to the
community to see what they can do. If you don't have the time to fix
bad queries, then you might want to stick to Oracle or MSSQL server.
OR spend the money you'd spend on those on a postgres hacker to see
what they can do for you.