Re: [PERFORM] large dataset with write vs read clients

2010-10-09 Thread Florian Weimer
* Greg Smith: Given the size of your database, I'd advise you consider a migration to a new version ASAP. 8.4 is a nice stable release at this point, that's the one to consider moving to. It also offers asynchronous commits, which might be a good tradeoff here (especially if the data

Re: [PERFORM] large dataset with write vs read clients

2010-10-09 Thread Mladen Gogala
I have a logical problem with asynchronous commit. The commit command should instruct the database to make the outcome of the transaction permanent. The application should wait to see whether the commit was successful or not. Asynchronous behavior in the commit statement breaks the ACID rules

[PERFORM] Slow count(*) again...

2010-10-09 Thread Neil Whelchel
I know that there haven been many discussions on the slowness of count(*) even when an index is involved because the visibility of the rows has to be checked. In the past I have seen many suggestions about using triggers and tables to keep track of counts and while this works fine in a

Re: [PERFORM] Slow count(*) again...

2010-10-09 Thread Scott Marlowe
On Sat, Oct 9, 2010 at 5:26 PM, Neil Whelchel neil.whelc...@gmail.com wrote: I know that there haven been many discussions on the slowness of count(*) even when an index is involved because the visibility of the rows has to be checked. In the past I have seen many suggestions about using

Re: [PERFORM] Slow count(*) again...

2010-10-09 Thread Mladen Gogala
Neil Whelchel wrote: I know that there haven been many discussions on the slowness of count(*) even when an index is involved because the visibility of the rows has to be checked. In the past I have seen many suggestions about using triggers and tables to keep track of counts and while this

Re: [PERFORM] Slow count(*) again...

2010-10-09 Thread Mladen Gogala
Joe Conway wrote: On 10/09/2010 06:54 PM, Mladen Gogala wrote: In another database, whose name I will not mention, there is a parameter db_file_multiblock_read_count which specifies how many blocks will be read by a single read when doing a full table scan. PostgreSQL is in dire need of

Re: [PERFORM] Slow count(*) again...

2010-10-09 Thread Neil Whelchel
On Saturday 09 October 2010 18:47:34 Scott Marlowe wrote: On Sat, Oct 9, 2010 at 5:26 PM, Neil Whelchel neil.whelc...@gmail.com wrote: I know that there haven been many discussions on the slowness of count(*) even when an index is involved because the visibility of the rows has to be

Re: [PERFORM] Slow count(*) again...

2010-10-09 Thread Samuel Gendler
On Sat, Oct 9, 2010 at 7:44 PM, Mladen Gogala mladen.gog...@vmsinfo.comwrote: The architects of Postgres database would be well advised to operate under the assumption that every production database has a competent DBA keeping an eye on the database. I'd actually go so far as to say that