view selection during query rewrite - Mailing list pgsql-general

From Vamsi Meduri
Subject view selection during query rewrite
Date
Msg-id CAB8vO9Sw7K2VWHz+Z3SqFJFzFG8zYyZTzNHqiXcnfzcR5yNYxw@mail.gmail.com
Whole thread Raw
Responses Re: view selection during query rewrite  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Suppose I have the following query and a view v1 defined as follows:
Q1: SELECT * FROM Table1 WHERE Table1.col1 = 5 and Table1.col2 LIKE '%abc%';
create view v1 as select * from Table1 where Table1.col1 = 5;

An effective way to execute Q1 would be to re-write it as: select * from v1 where col2 LIKE '%abc%'; provided that the selection predicates are highly selective and also if it is cheaper in execution time of the query.

However I see that postgres does not automatically perform query rewriting using view. I have looked at the plan using explain (analyze) and I see that Q1 is always executed using the base tables unless I explicitly mention the view in the query instead of the base table.

Is there a way to enforce automatic view selection in postgres or is it up to the user to write the query optimally?



pgsql-general by date:

Previous
From: Andy Fan
Date:
Subject: Re: Check what has been done for a uncommitted prepared transaction
Next
From: Tom Lane
Date:
Subject: Re: view selection during query rewrite