From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
---|---|
To: | Semyon Reyfman <sreyfman(at)therealauthority(dot)com>, <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Partitioning with the index on the master table. |
Date: | 2015-03-05 06:59:34 |
Message-ID: | 54F7FED6.7010209@BlueTreble.com |
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Lists: | pgsql-general |
On 3/4/15 9:25 AM, Semyon Reyfman wrote:
> I have a list-based partition table and I want to prevent scanning of all
> children tables in a JOIN, which is using the partition column. I know
> that CHECK constraints are not used in this case
Why do you say that? If properly written and with constraint_exclusion
<> 'off' and with good queries they will be.
> so I hope that creating an
> index on the partition column would help. But I am not sure if I should
> create this index on the master table or on each of children tables. It
> seems kind of strange to create an index on a children table where all
> values of the partition column are the same. So will an index on the master
> table be sufficient in this case?
It won't help unless you actually have data in the master table. Which
normally you wouldn't.
Basically, any indexing you do on a partitioned table must be done *on
the partitions*, not on the master table.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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