[postgis-users] Slow delete of duplicate rows
andy at squeakycode.net
Mon Mar 5 10:32:04 PST 2012
On 3/5/2012 11:15 AM, Nicolas Ribot wrote:
> Try the "NOT EXISTS" construct. I found it is order of magnitude
> faster than "NOT IN".
> It should be something like (test the query before using it, i'm not
> sure of it :)
> DELETE FROM portal.metadata
> WHERE NOT EXISTS
> SELECT MIN(idx)
> FROM portal.metadata
> GROUP BY "data_object.unique_id"
ahh, no, I dont think that's right. min() will always return a record,
so exists will always be true. exists() is true when count(*) > 0.
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