Re: Slow duplicate deletes - Mailing list pgsql-novice

From DrYSG
Subject Re: Slow duplicate deletes
Date
Msg-id 1330980227869-5538858.post@n5.nabble.com
Whole thread Raw
In response to Re: Slow duplicate deletes  (Merlin Moncure <mmoncure@gmail.com>)
Responses Re: Slow duplicate deletes  (Michael Wood <esiotrot@gmail.com>)
Re: Slow duplicate deletes  (Merlin Moncure <mmoncure@gmail.com>)
List pgsql-novice
One point I might not have made clear. The reason I want to remove duplicates
is that the column "data_object.unique_id" became non-unique (someone added
duplicate rows). So I added the bigSeriel (idx) to uniquely identify the
rows, and I was using the SELECT MIN(idx) and GroupBy to pick just one of
the rows that became duplicated.

I am going to try out some of your excellent suggestions. I will report back
on how they are working.

One idea that was given to me was the following (what do you think Merlin?)

CREATE TABLE portal.new_metatdata AS
select distinct on (data_object.unique_id) * FROM portal.metadata;

Or something of this ilk should be faster because it only need to do a
sort on data_object.unique_id and then an insert. After you have
verified the results you can do:

BEGIN;
ALTER TABLE portal.metatdata rename TO portal.new_metatdata_old;
ALTER TABLE portal.new_metatdata rename TO portal.metatdata_old;
COMMIT;


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