Re: CLUSTER and clustered indices

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <simon(at)2ndquadrant(dot)com>,<alvherre(at)commandprompt(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>,<tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: CLUSTER and clustered indices
Date: 2005-11-18 18:06:46
Message-ID: 437DC3D60200002500000844@gwmta.wicourts.gov
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That sounds very much like a CLUSTERED INDEX under Sybase ASE
(or the derivative Microsoft SQL Server). In those products, when you
create a clustered index, the data pages are sorted according to the
index sequence, and are used as the leaf pages in the index. A
clustered index does not have another leaf level.

>>> Simon Riggs <simon(at)2ndquadrant(dot)com> >>>

As an aside, Index Organized Tables (IOTs) isn't just an Oracle term.
They first used the term, but the concept had already been implemented
in both Tandem (value-ordered) and Teradata (hash-ordered) before this,
as well as numerous OLAP systems. The concept doesn't look to be
patented.

If anybody is looking for a justification for IOTs, the reduction in
table volume for large tables is very high. IOTs are the equivalent of
removing all of the leaf blocks of the clustered index.

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