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Re: PGSQL or other DB?

From: Tony Caduto <tony_caduto(at)amsoftwaredesign(dot)com>
To: durumdara <durumdara(at)gmail(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: PGSQL or other DB?
Date: 2009-01-30 20:33:12
Message-ID: 49836408.20901@amsoftwaredesign.com (view raw or flat)
Thread:
Lists: pgsql-general
durumdara wrote:
>
> Another important thing that I don't understand (what as I saw) that 
> the PostGreSQL is store the databases in one, unseparatable file set, 
> in a directory named data.
> In another databases, like DBISAM, FireBird, MySQL, the databases are 
> separated to another directories/files.
>
> This "one datadir" is seems to be not too good for us. We used DBISAM 
> in our clients, and many times when we got some filesystem error, we 
> can simply recover the tables - from the files.
> When we want to backup or restore one database, we can do it in two 
> way: a.) archive all files b.) make sql dump from database.
>

Postgresql uses a database cluster.  In the data directory each database 
goes into a directory identified by the database OID, and in this 
directory the database resides
in 2 gb chunks(as far as I remember).  You can easily backup the cluster 
by using the file system, you just have to make sure you stop the 
postmaster and then you can backup the entire data dir or individual 
database dir.  You have to restore this to the same version of PG though.
it's the same kind of deal with Firebird, you can't backup a running 
database with the file system and even Firebird must be stopped in order 
to do a file system copy of the database file.

Firebird also stores all it's transaction data in the same file, so you 
end up with HUGE files unless you do a backup and restore to shrink them 
down.  You don't have this problem with PostgreSQL as it stores that 
info in the WAL.

PostgreSQL will give the the best solution for your project hands down, 
just give it a chance and don't worry about what you did with Firebird 
or MySQL.

I have never had a PostgreSQL database or dump file become corrupt, but 
on Firebird it happens fairly often and it's part of the reason why I 
eventually dumped it and moved to PostgreSQL.

Hope that helps you out some.

Tony Caduto
AM Software Design
Home of Lightning Admin for PostgreSQL
http://www.amsoftwaredesign.com

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