> -----Original Message-----
> From: pgsql-hackers-owner@postgresql.org [mailto:pgsql-hackers-
> owner@postgresql.org] On Behalf Of Pavel Stehule
> Sent: Monday, January 11, 2010 11:55 PM
> To: PostgreSQL Hackers
> Cc: Tom Lane
> Subject: [HACKERS] planner or statistical bug on 8.5
>
> Hello
>
> I checked query and I was surprised with very strange plan:
>
> postgres=# create table a(a int primary key);
> NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index
> "a_pkey" for table "a"
> CREATE TABLE
> postgres=# create table b(b int primary key);
> NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index
> "b_pkey" for table "b"
> CREATE TABLE
> postgres=# create table c(c int primary key);
> NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index
> "c_pkey" for table "c"
> CREATE TABLE
> postgres=# ANALYZE ;
> ANALYZE
> postgres=# explain select a, b from a,b,c;
> QUERY PLAN
> -----------------------------------------------------------------------
> Nested Loop (cost=0.00..276595350.00 rows=13824000000 width=8)
> -> Nested Loop (cost=0.00..115292.00 rows=5760000 width=8)
> -> Seq Scan on a (cost=0.00..34.00 rows=2400 width=4)
> -> Materialize (cost=0.00..82.00 rows=2400 width=4)
> -> Seq Scan on b (cost=0.00..34.00 rows=2400 width=4)
> -> Materialize (cost=0.00..82.00 rows=2400 width=0)
> -> Seq Scan on c (cost=0.00..34.00 rows=2400 width=0)
> (7 rows)
You have no join columns, so it is a simple product.
Perhaps you meant something like this:
EXPLAIN SELECT a.a, b.b, c.c FROM a a, b b, c c WHERE a.a = b.b AND a.a = c.c
