Re: View's plan not taking advantage of WHERE?

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Mike Summers <msummers57(at)gmail(dot)com>
Cc: "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: View's plan not taking advantage of WHERE?
Date: 2013-06-05 12:08:22
Message-ID: CAOR=d=0rt=8FZ0AM2gRqx1Sv7Mog4BSc5RMAO=a8DC6c3cCxsw@mail.gmail.com
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On Wed, Jun 5, 2013 at 6:01 AM, Mike Summers <msummers57(at)gmail(dot)com> wrote:
> From what I'm reading the View is frozen when it's created, including it's
> plan, and the usual solution is to use a set returning function... is this
> not true?

No it is not. Here:

smarlowe=# create table a (id int);
CREATE TABLE
smarlowe=# create index a_id on a(id);
CREATE INDEX
smarlowe=# insert into a values (1),(2),(3);
INSERT 0 3
smarlowe=# create view x as select * from a;
CREATE VIEW

smarlowe=# analyze a;
ANALYZE
smarlowe=# show enable_seqscan;
enable_seqscan
----------------
on
(1 row)
smarlowe=# explain select * from x where id=1;
QUERY PLAN
-------------------------------------------------
Seq Scan on a (cost=0.00..1.04 rows=1 width=4)
Filter: (id = 1)
(2 rows)

smarlowe=# set enable_seqscan =off;
SET
smarlowe=# explain select * from x where id=1;
QUERY PLAN
--------------------------------------------------------------
Index Scan using a_id on a (cost=0.00..8.27 rows=1 width=4)
Index Cond: (id = 1)
(2 rows)

smarlowe=#

> I've double checked all schemas and the view is only defined once.

Well you're gonna have to come up with some kind of self-contained
test to show what's happening then.

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