Re: partitioning question 1
От | Ben |
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Тема | Re: partitioning question 1 |
Дата | |
Msg-id | 59555E0F-71C2-4062-AD23-F1B7B9993354@gmail.com обсуждение исходный текст |
Ответ на | Re: partitioning question 1 ("Igor Neyman" <ineyman@perceptron.com>) |
Ответы |
Re: partitioning question 1
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Список | pgsql-performance |
On Oct 29, 2010, at 7:38 AM, Igor Neyman wrote: >> is my intuition completely off on this? >> >> best regards, ben >> > > If your SELECT retrieves substantial amount of records, table scan could > be more efficient than index access. > > Now, if while retrieving large amount of records "WHERE clause" of this > SELECT still satisfies constraints on some partition(s), then obviously > one (or few) partition scans will be more efficient than full table scan > of non-partitioned table. > > So, yes partitioning provides performance improvements, not only > maintenance convenience. my impression was that a *clustered* index would give a lot of the same I/O benefits, in a more flexible way. if you'reclustered on the column in question, then an index scan for a range is much like a sequential scan over a partition(as far as i understand.) b
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