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Re: PostgreSQL clustering VS MySQL clustering

From: William Yu <wyu(at)talisys(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: PostgreSQL clustering VS MySQL clustering
Date: 2005-01-28 22:04:24
Message-ID: ctect8$et4$ (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Hervé Piedvache wrote:
>>My point being is that there is no free solution.  There simply isn't.
>>I don't know why you insist on keeping all your data in RAM, but the
>>mysql cluster requires that ALL data MUST fit in RAM all the time.
> I don't insist about have data in RAM .... but when you use PostgreSQL with 
> big database you know that for quick access just for reading the index file 
> for example it's better to have many RAM as possible ... I just want to be 
> able to get a quick access with a growing and growind database ...

If it's an issue of RAM and not CPU power, think about this scenario. 
Let's just say you *COULD* partition your DB over multiple servers. What 
  are your plans then? Are you going to buy 4 Dual Xeon servers? Ok, 
let's price that out.

For a full-blown rackmount server w/ RAID, 6+ SCSI drives and so on, you 
are looking at roughly $4000 per machine. So now you have 4 machines -- 
total of 16GB of RAM over the 4 machines.

On the otherhand, let's say you spent that money on a Quad Opteron 
instead. 4x850 will cost you roughly $8000. 16GB of RAM using 1GB DIMMs 
is $3000. If you went with 2GB DIMMs, you could stuff 32GB of RAM onto 
that machine for $7500.

Let's review the math:

4X server cluster, total 16GB RAM = $16K
1 beefy server w/ 16GB RAM = $11K
1 beefy server w/ 32GB RAM = $16K

I know what I would choose. I'd get the mega server w/ a ton of RAM and 
skip all the trickyness of partitioning a DB over multiple servers. Yes 
your data will grow to a point where even the XXGB can't cache 
everything. On the otherhand, memory prices drop just as fast. By that 
time, you can ebay your original 16/32GB and get 64/128GB.

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