Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

On 12/26/05, David Lang <[EMAIL PROTECTED]> wrote: > raid5 writes n+1 blocks not n+n/2 (unless n=2 for a 3-disk raid). you can > have a 15+1 disk raid5 array for example > > however raid1 (and raid10) have to write 2*n blocks to disk. so if you are > talking about pure I/O needed raid5 wins hands d

Re: [PERFORM] Performance hit on large row counts

David Scott <[EMAIL PROTECTED]> writes: > I didn't mention I was the only user with transactions open on the > system during this. Would cluster eliminate more rows then vacuum full > if the only open transaction is the one running the vacuum and it is a > clean transaction? It wouldn't el

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

On Mon, 26 Dec 2005, Alex Turner wrote: Yes, but those blocks in RAID 10 are largely irrelevant as they are to independant disks. In RAID 5 you have to write parity to an 'active' drive that is part of the stripe. (They are irrelevant unless of course you are maxing out your SCSI bus - yet an

Re: [PERFORM] Performance hit on large row counts

Tom Lane wrote: The CLUSTER may be affecting things in some other way, like by squeezing out dead tuples causing a reduction in the total table and index sizes. I didn't mention I was the only user with transactions open on the system during this. Would cluster eliminate more rows then

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

Yes, but those blocks in RAID 10 are largely irrelevant as they are to independant disks. In RAID 5 you have to write parity to an 'active' drive that is part of the stripe. (They are irrelevant unless of course you are maxing out your SCSI bus - yet another reason why SATA can be faster than SCS

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

Yes - they work excellently. I have several medium and large servers running 3ware 9500S series cards with great success. We have rebuilding many failed RAID 10s over the course with no problems. Alex On 12/26/05, Benjamin Arai <[EMAIL PROTECTED]> wrote: > Have you have any experience rebuildin

Re: [PERFORM] Bitmap indexes etc.

Ivan Voras <[EMAIL PROTECTED]> writes: > This is PostgreSQL 8.1.0. > - what does "Bitmap Heap Scan" phase do? A plain indexscan fetches one tuple-pointer at a time from the index, and immediately visits that tuple in the table. A bitmap scan fetches all the tuple-pointers from the index in one g

[PERFORM] Bitmap indexes etc.

Hi! This is not actually a question about performance, but an inquiry to help me understand what is going on. Below this text are two EXPLAIN ANALYZE outputs, before and after VACUUM ANALYZE was run. I have several questions about the proposed plans (mostly the first one). There is only one ta

Re: [PERFORM] Performance hit on large row counts

David Scott <[EMAIL PROTECTED]> writes: > We are trying to ascertain if we are up against the limits of what > postgres can accomplish without having the tables clustered. ... > We are aware that there is a minimum time that is required to resolve > the index values against the table to ascerta

[PERFORM] Performance hit on large row counts

We are trying to ascertain if we are up against the limits of what postgres can accomplish without having the tables clustered. We would prefer not to have to cluster our tables because according to the documentation this is a one time operation and not maintained. Is there any other performa

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

Benjamin, On 12/26/05 10:21 AM, "Benjamin Arai" <[EMAIL PROTECTED]> wrote: > Have you have any experience rebuilding arrays in linux using the 3Ware > utilities? If so, did it work well? Sure we have - nowadays with disks failing as much as they do how could we not? ;-) 3Ware has some *nice* t

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

Have you have any experience rebuilding arrays in linux using the 3Ware utilities?  If so, did it work well? Luke Lonergan wrote: Benjamin, Have you done any benchmarking of the 9550SX against a software raid configuration? Interesting - no, not on SATA, mostly bec

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

On Mon, 26 Dec 2005, Alex Turner wrote: It's irrelavent what controller, you still have to actualy write the parity blocks, which slows down your write speed because you have to write n+n/2 blocks. instead of just n blocks making the system write 50% more data. RAID 5 must write 50% more data t

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

It's irrelavent what controller, you still have to actualy write the parity blocks, which slows down your write speed because you have to write n+n/2 blocks. instead of just n blocks making the system write 50% more data. RAID 5 must write 50% more data to disk therefore it will always be slower.

[PERFORM] Fwd: vacuuming template0 gave ERROR

-- Forwarded message --From: Gourish Singbal <[EMAIL PROTECTED]>Date: Dec 26, 2005 5:04 PM Subject: vacuuming template0 gave ERRORTo: "pgsql-admin@postgresql.org"   Guys,   Got the following ERROR when i was vacuuming the template0 database. postgresql

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

Benjamin, > Have you done any benchmarking of the 9550SX against a software raid > configuration? Interesting - no, not on SATA, mostly because I've had awful luck with Linux drivers and SATA. The popular manufacturers of SATA to PCI bridge chipsets are Silicon Image and Highpoint, and I'

Re: [PERFORM] What's the best hardver for PostgreSQL 8.1?

Have you done any benchmarking of the 9550SX against a software raid configuration?  Luke Lonergan wrote: Frank, You definitely DO NOT want to do RAID 5 on a database server. That is probably the worst setup you could have, I've seen it have lower performance than just a