Jim C. Nasby wrote:
It will probably be a win to come up with a list of potential records
from each table, instead of after doing the 3-way join. so something
like:
(SELECT gazPlaceID FROM gazPlaces GROUP BY featureType HAVING
count(*)=1)
JOIN
(SELECT ...)
Hmm, not sure I understand. Joining the uniques wrt each of the three
columns does not result in the unique triples, or even a superset of
them, at least in this case.
If you post the output of explain (or explain analyze is even better)
then people could probably make better suggestions.
Okay, I just posted the query plan. I will try to run an EXPLAIN
ANALYZE tonight.
Again, I'm also interested in completely different approaches to
discovering the entities with unique attribute combinations.
Intuitively, the query I posted is doing "too much work", because it's
computing the total count for each combo, when all I really need is to
know if the count is 1 or greater than 1.
Thanks!
- John Burger
MITRE
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