Re: Separate tablespaces for indexes on same table?

From: Connor McDonald <hamcdc_at_yahoo.co.uk>
Date: Fri, 19 Oct 2001 10:08:22 -0700
Message-ID: <F001.003B0272.20011019102056@fatcity.com>

What really matter is avoiding IO overload on a single device - and that depends on usage. The ol' tale about separating tables and indexes is just a special case of that (and probably obsolete).

You need to have an idea of

- how often each index is used
- if they are used together
- if they are used with the table (counts etc can be

done with just the index and not the table at all).

Based on this, you come up with the IO separation you would required. This could be 1 index on an 8 disk stripe (because its hammered), and all the rest somewhere else. It could be each index on separate stripes - because they are all hammered at the same time. It could be all on a single stripe - because typically only 1 get used at a time.

You just need to be able to model what and when is going to run (monitoring v$filestat is a very good means for this) and planning (adjusting) accordingly.

hth
connor

• Cherie_Machler_at_gelco.com wrote: >
  > I am rebuilding some indexes for a 20-Gig table. I
  > am following the
  > recommendations in the paper How to Stop
  > Defragmenting and Start Living...
  >
  > There are six indexes on this table. According to
  > the paper, I should
  > create a separate tablespace for these indexes. My
  > question is: Should I
  > put all of the indexes in a single tablespace or
  > should I make two
  > tablespaces and separate them. In some queries,
  > the indexes may be used
  > together but in most they will not. If I put them
  > in a single tablespace,
  > will that cause I/O contention.
  >
  > This is on 8.0.4 Sun E10K Solaris 2.6 with Veritas
  > Quick I/O.
  >
  > Thanks,
  >
  > Cherie Machler
  > Gelco Information Network
  >
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  > Please see the official ORACLE-L FAQ:
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Connor McDonald
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Received on Fri Oct 19 2001 - 12:08:22 CDT