RE: separate tablespaces for tables and indexes

  • From: "Gogala, Mladen" <MGogala@xxxxxxxxxxxxxxxxxxxx>
  • To: "'richard.foote@xxxxxxxxxxx'" <richard.foote@xxxxxxxxxxx>, Mladen Gogala <gogala@xxxxxxxxxxxxx>
  • Date: Tue, 14 Dec 2004 09:57:14 -0500

Richard, I am still not convinced, and for the following reason:
The alternatives were: splitting indexes and tables in their separate 
tablespaces vs. leaving them in one tablespace. If you leave them in one
tablespace, then 1100 LIO/sec is what you get, because both of your disks 
will be a part of the same tablespace. Tablespace blocks are allocated
sequentially and, if you put both "disks", in the same file, you will end up
exactly with what you say you don't propose. 
In order to make separation policy viable and easy to document you have to
adopt one of the two principles mentioned before. Second policy (size based)
does not put indexes and tables in the same tablespace, because indexes are
usually smaller. The first policy would render exactly what you described as
a big no-no: everything in a single place, with 1100/sec.
Mladen Gogala
Ext. 121

-----Original Message-----
From: Richard Foote [mailto:richard.foote@xxxxxxxxxxx] 
Sent: Tuesday, December 14, 2004 9:23 AM
To: Mladen Gogala
Cc: DGoulet@xxxxxxxx; JBECKSTROM@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx;
ORACLE-L@xxxxxxxxxxxxx; oracledba@xxxxxxxxxxx; oracle-rdbms@xxxxxxxxxxxxxxx
Subject: Re: separate tablespaces for tables and indexes

Hi Mladen,

Please don't beg, I hate it when people beg. Let's make this really really 
really simple:

Disk 1 Tables Only => 1000 I/Os per second

Disk 2 Indexes Only => 100 I/Os per second

I'm not suggesting:

Disk 1 Tables and Indexes => 1100 I/Os per second

Disk 2 Nothing

but something like

Disk 1 1/2 Tables and Indexes => 550 I/Os per second

Disk 2 other 1/2 Tables and Indexes => 550 I/Os per second

How is Disk 1 or 2 "hotter still" in your words ?

The number of times people claim to improve performance by separating 
indexes/tables only to find they've added a heap of extra disks whilst 

Perhaps the extra (or in your case the reduction) of disks may just be a 
contributing factor ...




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