If the partitioned column in your where clause does not use hardcoded values ...e.g datecolumn between 'year1' and 'year2' ..the query planner will check all partitions ..this is a known issue with the optimizer On Mon, Mar 8, 2010 at 10:28 AM, Konrad Garus <konrad.garus@xxxxxxxxx> wrote: > Hello, > > I am evaluating a materialized view implemented as partitioned table. > At the moment the table is partitioned yearly and contains 5 > numeric/timestamp columns. One of the columns is ID (but it's not what > the table is partitioned on). > > Partition for one year occupies about 1200 MB. Each of the columns is > indexed, with each index weighing about 160 MB. I am trying to avoid > RAM/disk thrashing. Now I have the following questions: > > 1. When I query the table by ID, it performs index scan on each > partition. The result is only found in one partition, but I understand > why it needs to look in all of them. How much disk reading does it > involve? Is only the "head" of indexes for partitions that do not > include the row scanned, or are always whole indexes read? I would > like to know the general rule for index scans. > > 2. Is it possible to tell which PG objects are read from disk (because > they were not found in RAM)? > > Thank you. > > -- > Konrad Garus > > -- > Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
