Re: [GENERAL] Benchmarks - Mailing list pgsql-general
From | Differentiated Software Solutions Pvt. Ltd. |
---|---|
Subject | Re: [GENERAL] Benchmarks |
Date | |
Msg-id | 000101bf58d7$ad7370a0$1db6c5cb@nagma Whole thread Raw |
List | pgsql-general |
Hi, I had posted a message yesterday on 4 things which bugged me about postgres while running a 24x7 app. This discussion has degenrated into a discussion on vacuum. Now here is a person (Michael), who wants help to decide whether postgres is the right choice or not. It would be nice to help him... Please contribute to helping him decide. I want more responses on pg experiences with 24x7 apps. Bye, Murali -----Original Message----- From: The Hermit Hacker <scrappy@hub.org> To: Differentiated Software Solutions Pvt. Ltd. <diffs@vsnl.com> Cc: Michael Cornelison <mcornel@magnify.com>; pgsql-general@hub.org <pgsql-general@hub.org>; Kimi <kimi@intercept.co.in> Date: 06 January 2000 19:05 Subject: Re: [GENERAL] Benchmarks >On Thu, 6 Jan 2000, Differentiated Software Solutions Pvt. Ltd. wrote: > >> b) There are quite a few things which you'd take for granted in other DBs >> which postgres does not have. Quite late in the day I was shocked to find >> that postgres does not have roll-forward transaction logging. They have >> Multi-version concurrency control and rollback support but you can't restore >> a backup and play logs !! > >Being worked on...as memory serves, should be in v7.1, as its part of the >WAL work that Vadim is doing...scheduale: this summer > >> c) Another issue which rankles me a lot is that postgres maintains different >> tables in different files. I remember lots of debate on this issue between >> 1993 and 95 and most DBMS's have settled down into having all tables within >> their own file structure... presumably to take over buffering and other >> mechanisms from the OS onto themselves. I have even read literature where >> Oracle and DB2 allow U to create DB's on raw UNIX partitions. I'm not sure >> whether they are still used. > >There are several schools of thought on this one...I've read documentation >from Oracle that recommends against doing this, since the operating >itself, in most cases, will do a much better job of disk I/O...there are >generally ways of tweaking your OS to increase various things like disk >buffering and what not... > >> d) Postgres manual recommends a nightly vacuum. I read this also a bit >> late. This is equivalent of rebuild database. While this is in >> progress all other clients wait for vacuum release locks. This is >> really a handicap for a 24x7 app. > >rebuild? first off, vacuum is a 'cleanup tool'...it goes through and >removes unwanted/junk/deleted records from the database...if you do alot >of update/delete operations, then, yes, do a vacuum reasonably >often. nightly though? depends on how much your data changes. a vacuum >gives you nothing really on a database that is purely insert data. > >actually, there has been talk about, and work started on, getting rid of >the 'locking' issue...with the MVCC code, the lock *shouldn't* be required >anymore, but Tom Lane(?) did some preliminary work on removing this for >v7.0 and ran into a few roadblocks, especially where there was the risk of >simultaneous vacuum's happening...wasn't a pretty sight, if memory >serves... > >> At the same time.... postgres would be a great choice when you have >> a) hardware resource constraints >> b) Less money to buy software >> c) your app is not mission critical and 24x7. > >I love these two works "mission critical"...I run several applications >that clients consider to be mission critical, the least of which are two >accounting systems for dial-up ISPs...about the only time their databases >go down is when we upgrade or have to reboot the physical machine... > > >Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy >Systems Administrator @ hub.org >primary: scrappy@hub.org secondary: scrappy@{freebsd|postgresql}.org >
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