Kevin Murphy <murphy@xxxxxxxxxxxxxxx> writes: > 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; Pretty much, but the first is probably faster. CLUSTER is not the speediest possible way of sorting data :-( > 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? Yeah, putting fixed-width fields first is usually a (marginal) win. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
