Обсуждение: Question about PostgreSQL from Delphi newsgroups
Hi, Someone asked me a question about PostgreSQL on the Delphi newsgroups and I was not sure how to answer them: "Do you know if using PostgreSQL a query or connection can have a priority set, so it can run quicker than other queries? For example, in a POS system the reporting queries should have lower priority than the generated invoices insert queries. " Thanks, Tony
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On Thu, 15 Nov 2007 15:00:00 -0600
Tony Caduto <tony_caduto@amsoftwaredesign.com> wrote:
> Hi,
> Someone asked me a question about PostgreSQL on the Delphi newsgroups
> and I was not sure how to answer them:
>
> "Do you know if using PostgreSQL a query or connection can have a
> priority set, so it can run quicker than other queries?
No.
Sincerely,
Joshua D. Drake
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On Thu, Nov 15, 2007 at 03:00:00PM -0600, Tony Caduto wrote: > > "Do you know if using PostgreSQL a query or connection can have a > priority set, so it can run quicker than other queries? No, it can't. The archives contain a lot of discussion about this issue. Look in -performance first, I think. A -- Andrew Sullivan Old sigs will return after re-constitution of blue smoke
On Nov 15, 2007 3:00 PM, Tony Caduto <tony_caduto@amsoftwaredesign.com> wrote: > Hi, > Someone asked me a question about PostgreSQL on the Delphi newsgroups > and I was not sure how to answer them: > > "Do you know if using PostgreSQL a query or connection can have a > priority set, so it can run quicker than other queries? > For example, in a POS system the reporting queries should have lower > priority than the generated invoices insert queries. " The answer is Yes, No, and sort of. It is possible to set different priorities on various backend processes by means things like renice etc... There are issues of priority inversion (look it up on wikipedia) that may or may not affect you, and changing the priority may or may not help, because in most OSes process priority does not translate to I/O priority, which is usually the real underlying issue. My recommendation is that if you want to have a live fast transactional database, AND you want to run reports, then you should something like slony replication and run your reports against the slave server. It certainly works well for me.