Re: finding UNIQUES in information_schema

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Gerardo Herzig <gherzig(at)fmed(dot)uba(dot)ar>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: finding UNIQUES in information_schema
Date: 2009-04-16 20:09:56
Message-ID: 3622.1239912596@sss.pgh.pa.us
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Gerardo Herzig <gherzig(at)fmed(dot)uba(dot)ar> writes:
> Tom Lane wrote:
>> No, they contain information about constraints, period. How did you
>> create those indexes? If you made them via SQL-standard PRIMARY KEY or
>> UNIQUE constraint syntax, they should show in the information_schema.
>> Otherwise not.

> Well, i just dont get it.

No, apparently not. The term "constraint" in this context has a very
specific meaning; it's talking about the CONSTRAINT syntax in CREATE
TABLE or ALTER TABLE. This is per SQL specification. Indexes are an
implementation detail that the standard doesn't concern itself with;
therefore anything you do with CREATE INDEX is outside the standard and
is not reflected in the standard-defined information_schema.

regards, tom lane

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