CONNECT BY with CROSS JOIN and WHERE not executing as described in doc

Question

Hello all,
please see these two statements. They are the same, but the 1st uses t1 INNER JOIN t2 while the snd uses a CROSS JOIN with WHERE.
The 2nd statement shows one row more than the first, but the CROSS JOIN with WHERE is the same as the INNER JOIN.
The result would be OK if Oracle did:
JOIN -> CONNECT BY PRIOR -> WHERE
But according to the docs it does:
JOIN (and WHEREs for JOINS) -> CONNECT BY PRIOR -> Rest of WHERE
See http://docs.oracle.com/cd/E11882_01/server.112/e26088/queries003.htm#SQLRF52332 for details. There it says:
Oracle processes hierarchical queries as follows:
A join, if present, is evaluated first, whether the join is specified in the FROM clause or with WHERE clause predicates.
The CONNECT BY condition is evaluated.
Any remaining WHERE clause predicates are evaluated.
+.....+
Is this a bug? I'd say yes, because it differs from the docs and it also is not what people are used to ("a,b WHERE" is the same as "a INNER JOIN b").
Thanks,
Blama
--Statement 1:
WITH t1
AS
(SELECT 1 a, 2 b FROM DUAL UNION ALL
SELECT 2 a, 3 b FROM DUAL UNION ALL
SELECT 3 a, 4 b FROM DUAL UNION ALL
SELECT 4 a, 5 b FROM DUAL UNION ALL
SELECT 5 a, 6 b FROM DUAL),
t2 AS
(SELECT 1 c FROM DUAL UNION ALL
SELECT 2 c FROM DUAL UNION ALL
SELECT 3 c FROM DUAL UNION ALL
SELECT 5 c FROM DUAL)
SELECT DISTINCT t1.a, t2.c, t1.b, level, SYS_CONNECT_BY_PATH(t1.a, '/') Path
FROM t1 INNER JOIN t2
ON t1.a = t2.c
CONNECT BY t1.a = PRIOR t1.b
START WITH t1.a = 1
ORDER BY
1,2,3;
--Result:
--1     1     2     1     /1
--2     2     3     2     /1/2
--3     3     4     3     /1/2/3
--Statement 2:
WITH t1
AS
(SELECT 1 a, 2 b FROM DUAL UNION ALL
SELECT 2 a, 3 b FROM DUAL UNION ALL
SELECT 3 a, 4 b FROM DUAL UNION ALL
SELECT 4 a, 5 b FROM DUAL UNION ALL
SELECT 5 a, 6 b FROM DUAL),
t2 AS
(SELECT 1 c FROM DUAL UNION ALL
SELECT 2 c FROM DUAL UNION ALL
SELECT 3 c FROM DUAL UNION ALL
SELECT 5 c FROM DUAL)
SELECT DISTINCT t1.a, t2.c, t1.b, level, SYS_CONNECT_BY_PATH(t1.a, '/') Path
FROM t1 CROSS JOIN t2
WHERE t1.a = t2.c
CONNECT BY t1.a = PRIOR t1.b
START WITH t1.a = 1
ORDER BY
1,2,3;
--Result:
--1     1     2     1     /1
--2     2     3     2     /1/2
--3     3     4     3     /1/2/3
--5     5     6     5     /1/2/3/4/5My details:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
CORE     11.2.0.2.0     Production
TNS for Solaris: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production

Answer 1

blama wrote:
Hello Paul,
that means that "a,b" isn't the same as "a CROSS JOIN b".
I don't think that that is really the case.
Do you have docs on this one?No explicit docs just (my) logic - having said that, I suppose it is implied that if you are doing ANSI style joins, it's not the where clauses that
are specifying the join.
If you do t1,t2 where t1.a=t2.a then Oracle figures out the kind of join from the (relevant) where clauses and treats the other where clauses after the CONNECT BY.
If you do t1 cross join t2 where t1.a=t2.a then you are saying the join is completely specified by the CROSS JOIN - i.e it's Cartesian. Oracle doesn't look at the where clauses for this. Therefore
all where clauses are treated as 'other' and are evaluated after the CONNECT BY.
So, in my mind it's 10g that has the bug.