[PERFORM] a question about Direct I/O and double buffering

Hi, A page may be double buffered in PG's buffer pool and in OS's buffer cache. Other DBMS like DB2 and Oracle has provided Direct I/O option to eliminate double buffering. I noticed there were discusses on the list. But I can not find similar option in PG. Does PG support direct I/O now? The

Re: [PERFORM] a question about Direct I/O and double buffering

Erik Jones wrote: On Apr 5, 2007, at 12:09 PM, Xiaoning Ding wrote: Hi, A page may be double buffered in PG's buffer pool and in OS's buffer cache. Other DBMS like DB2 and Oracle has provided Direct I/O option to eliminate double buffering. I noticed there were discusses on the list. But I

Re: [PERFORM] a question about Direct I/O and double buffering

Alex Deucher wrote: On 4/5/07, Erik Jones [EMAIL PROTECTED] wrote: On Apr 5, 2007, at 1:22 PM, Xiaoning Ding wrote: Erik Jones wrote: On Apr 5, 2007, at 12:09 PM, Xiaoning Ding wrote: Hi, A page may be double buffered in PG's buffer pool and in OS's buffer cache. Other DBMS like DB2

Re: [PERFORM] scalablility problem

I repeated the test again. It took 0.92 second under 8.2.3. I checked system load using top and ps. There is no other active processes. Xiaoning Ron Mayer wrote: Xiaoning Ding wrote: Postgresql is 7.3.18. [...] 1 process takes 0.65 second to finish. I update PG to 8.2.3. The results

Re: [PERFORM] scalablility problem

Scott Marlowe wrote: On Fri, 2007-03-30 at 15:25, Xiaoning Ding wrote: Hi all, When I run multiple TPC-H queries (DBT3) on postgresql, I found the system is not scalable. My machine has 8GB memory, and 4 Xeon Dual Core processor ( 8 cores in total). OS kernel is linux 2.6.9. Postgresql

Re: [PERFORM] scalablility problem

Christopher Browne wrote: Quoth [EMAIL PROTECTED] (Xiaoning Ding): When I run multiple TPC-H queries (DBT3) on postgresql, I found the system is not scalable. My machine has 8GB memory, and 4 Xeon Dual Core processor ( 8 cores in total). OS kernel is linux 2.6.9. Postgresql is 7.3.18. I I

Re: [PERFORM] scalablility problem

Michael Stone wrote: On Fri, Mar 30, 2007 at 10:00:30PM -0600, Guido Neitzer wrote: On 30.03.2007, at 19:18, Christopher Browne wrote: 2. There are known issues with the combination of Xeon processors and PAE memory addressing; that sort of hardware tends to be *way* less speedy than the

Re: [PERFORM] scalablility problem

Tom Lane wrote: Joshua D. Drake [EMAIL PROTECTED] writes: I use RHEL 4. I can not understand how the scalability related with shared memory? It isn't RHEL4 and shared memory. It is PostgreSQL and shared memory. Things have changed with PostgreSQL since 7.3 (7.3 is really god awful old) that

[PERFORM] scalablility problem

Hi all, When I run multiple TPC-H queries (DBT3) on postgresql, I found the system is not scalable. My machine has 8GB memory, and 4 Xeon Dual Core processor ( 8 cores in total). OS kernel is linux 2.6.9. Postgresql is 7.3.18. I run multiple q2 queries simultaneously. The results are: 1

Re: [PERFORM] scalablility problem

with pre 8.1 versions? Xiaoning Tom Lane wrote: Xiaoning Ding [EMAIL PROTECTED] writes: When I run multiple TPC-H queries (DBT3) on postgresql, I found the system is not scalable. My machine has 8GB memory, and 4 Xeon Dual Core processor ( 8 cores in total). OS kernel is linux 2.6.9. Postgresql