From: Carlo Stonebanks <stonec.register@sympatico.ca>
To: pgsql-performance@postgresql.org
Subject: Composite keys
Date: Tue, 11 Oct 2011 11:16:07 -0400
Message-ID: <CCB4B01D184042ECBBE456D1ACB185A4@CAPRICA> (raw)
Excuse the noob question, I couldn't find any reading material on this
topic.
Let's say my_table has two fields, pkey_id and another_id. The primary key
is pkey_id and of course indexed.
Then someone adds a composite index on btree(pkey_id, another_id).
Question 1) Is there any benefit to having pkey_id in the second index
(assuming the index was created to satisfy some arbitrary WHERE clause)?
Question 2) Regardless of the answer to Question 1 - if another_id is not
guaranteed to be unique, whereas pkey_id is - there any value to changing
the order of declaration (more generally, is there a performance impact for
column ordering in btree composite keys?)
Thanks,
Carlo
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To: pgsql-performance@postgresql.org
Cc: stonec.register@sympatico.ca
Subject: Re: Composite keys
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