Hi,I'm using inherited tables to partition some data which can grow very large. Recently I discovered that a simple query that on a regular table would use an index was instead using seq scans (70s vs a guessed 2s).
The well known query is:
SELECT foo FROM bar ORDER BY foo DESC LIMIT 1 (The same applies for SELECT MIN(foo) FROM bar using 8.1)The query plan generated when running the query on a table which has inheritance forces the planner to choose a seq_scan for each table. Wouldn't be a good thing to also promote ORDER BYs and LIMITs to each subscan (like WHERE does)?
I needed a quick solution, so I wrote a function which looks each inherited table separately and my problem is partially solved, but I think that a (hopefully) little change in the optimizer could be advisable.
Attached are some EXPLAIN ANALYZE outputs of my suggestion. Best regards -- Matteo Beccati http://phpadsnew.com http://phppgads.com
order_limit_inheritance.txt
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