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Re: splitting data into multiple tables

From: Andres Freund <andres(at)anarazel(dot)de>
To: pgsql-performance(at)postgresql(dot)org
Cc: nair rajiv <nair331(at)gmail(dot)com>, Craig James <craig_james(at)emolecules(dot)com>
Subject: Re: splitting data into multiple tables
Date: 2010-01-26 00:49:09
Message-ID: 201001260149.09410.andres@anarazel.de (view raw or flat)
Thread:
Lists: pgsql-performance
On Tuesday 26 January 2010 01:39:48 nair rajiv wrote:
> On Tue, Jan 26, 2010 at 1:01 AM, Craig James 
<craig_james(at)emolecules(dot)com>wrote:
>           I am working on a project that will take out structured content
> from wikipedia
> and put it in our database. Before putting the data into the database I
> wrote a script to
> find out the number of rows every table would be having after the data is
> in and I found
> there is a table which will approximately have 50,000,000 rows after data
> harvesting.
> Is it advisable to keep so much data in one table ?
Depends on your access patterns. I.e. how many rows are you accessing at the 
same time - do those have some common locality and such.


>           I have read about 'partitioning' a table. An other idea I have is
> to break the table into
> different tables after the no of rows  in a table has reached a certain
> limit say 10,00,000.
> For example, dividing a table 'datatable' to 'datatable_a', 'datatable_b'
> each having 10,00,000 rows.
> I needed advice on whether I should go for partitioning or the approach I
> have thought of.
Your approach is pretty close to partitioning - except that partitioning makes 
that mostly invisible to the outside so it is imho preferrable.

>           We have a HP server with 32GB ram,16 processors. The storage has
> 24TB diskspace (1TB/HD).
> We have put them on RAID-5. It will be great if we could know the
> parameters that can be changed in the
> postgres configuration file so that the database makes maximum utilization
> of the server we have.
> For eg parameters that would increase the speed of inserts and selects.
Not using RAID-5 possibly would be a good start - many people (me included) 
experienced bad write performance on it. It depends a great deal on the 
controller/implementation though.
RAID-10 is normally to be considered more advantageous despite its lower 
usable space ratio.
Did you create one big RAID-5 out of all disks? Thats not a good idea, because 
its pretty likely that another disk fails while you restore a previously 
failed disk. Unfortunately in that configuration that means you have lost your 
complete data (in the most common implementations at least).

Andres

PS: Your lines are strangely wrapped...

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