Re: Materialized views don't show up in information_schema

From: David G Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Materialized views don't show up in information_schema
Date: 2014-10-17 09:31:00
Message-ID: 1413538260940-5823379.post@n5.nabble.com
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Nicolas Barbier wrote
> 2014-10-16 Stephen Frost &lt;

> sfrost@

> &gt;:
>
>> Alright, coming back to this, I have to ask- how are matviews different
>> from views from the SQL standard's perspective?
>
> Matviews that are always up to date when you access them are
> semantically exactly the same as normal views. Matviews that can get
> out of date, however, are not.

Materialized Views share features and properties of both tables and views -
and omit capabilities available to both as well. The performance
optimization spoken of is basically the table aspect of the feature while
the backing query makes it look like a view. But all the while it is a
distinct feature and one not described in the SQL standard.

From a read-only perspective I can see the value of having this particular
row-source available in the standard information schema but anything trying
to manipulate a matview as either a view or a table will be surprised.

Since the standard doesn't distinguish between read and write aspects of the
object types there isn't a safe way to add matviews to the information
schema that doesn't violate the intent of the provided view. If the
application/users wants to support/use PostgreSQL specific features it/they
have to be ready and able to use the catalog.

David J.

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