CLUSTER equivalent

From: Kevin Murphy <murphy(at)genome(dot)chop(dot)edu>
To: PostgreSQL general <pgsql-general(at)postgresql(dot)org>
Subject: CLUSTER equivalent
Date: 2005-08-02 13:11:46
Message-ID: 42EF7112.9040300@genome.chop.edu
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Are the two following options equivalent?

OPTION A (ordered insert):

CREATE TABLE table1 (cluster_col TEXT, col2 INTEGER);
CREATE INDEX idx1 ON table1(cluster_col);
INSERT INTO table1 (cluster_col, col2) SELECT cluster_col, col2 FROM
table1 ORDER BY cluster_col;

OPTION B (unordered insert followed by CLUSTER):

CREATE TABLE table1 (cluster_col TEXT, col2 INTEGER);
CREATE INDEX idx1 ON table1(cluster_col);
INSERT INTO table1 (cluster_col, col2) SELECT cluster_col, col2 FROM table1;
CLUSTER idx1 ON table1;

Thanks,
Kevin Murphy

P.S. On another topic, did I gather correctly from a recent thread that
it would be more efficient to define the above table (if it were really
only two columns) as:

create table clustered_tagged_genes (integer pmid, text mention);

i.e., with the integer field before the text field?

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