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Re: PostgreSQL clustering VS MySQL clustering

From: Marty Scholes <marty(at)outputservices(dot)com>
To: herve(at)elma(dot)fr, pgsql-performance(at)postgresql(dot)org
Cc: Marty Scholes <marty(at)outputservices(dot)com>
Subject: Re: PostgreSQL clustering VS MySQL clustering
Date: 2005-01-21 18:18:00
Message-ID: 41F14758.4030602@outputservices.com (view raw or flat)
Thread:
Lists: pgsql-performance
This is probably a lot easier than you would think.  You say that your 
DB will have lots of data, lots of updates and lots of reads.

Very likely the disk bottleneck is mostly index reads and writes, with 
some critical WAL fsync() calls.  In the grand scheme of things, the 
actual data is likely not accessed very often.

The indexes can be put on a RAM disk tablespace and that's the end of 
index problems -- just make sure you have enough memory available.  Also 
make sure that the machine can restart correctly after a crash: the 
tablespace is dropped and recreated, along with the indexes.  This will 
cause a machine restart to take some time.

After that, if the WAL fsync() calls are becoming a problem, put the WAL 
files on a fast RAID array, etiher a card or external enclosure, that 
has a good amount of battery-backed write cache.  This way, the WAL 
fsync() calls will flush quickly to the RAM and Pg can move on while the 
RAID controller worries about putting the data to disk.  With WAL, low 
access time is usually more important than total throughput.

The truth is that you could have this running for not much money.

Good Luck,
Marty

> Le Jeudi 20 Janvier 2005 19:09, Bruno Almeida do Lago a écrit :
>  > Could you explain us what do you have in mind for that solution? I mean,
>  > forget the PostgreSQL (or any other database) restrictions and 
> explain us
>  > how this hardware would be. Where the data would be stored?
>  >
>  > I've something in mind for you, but first I need to understand your 
> needs!
> 
> I just want to make a big database as explained in my first mail ... At the
> beginning we will have aprox. 150 000 000 records ... each month we will 
> add
> about 4/8 millions new rows in constant flow during the day ... and in same
> time web users will access to the database in order to read those data.
> Stored data are quite close to data stored by google ... (we are not 
> making a
> google clone ... just a lot of data many small values and some big ones ...
> that's why I'm comparing with google for data storage).
> Then we will have a search engine searching into those data ...
> 
> Dealing about the hardware, for the moment we have only a bi-pentium Xeon
> 2.8Ghz with 4 Gb of RAM ... and we saw we had bad performance results 
> ... so
> we are thinking about a new solution with maybe several servers (server
> design may vary from one to other) ... to get a kind of cluster to get 
> better
> performance ...
> 
> Am I clear ?
> 
> Regards,




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