On 2016/03/28 18:17, Rajkumar Raghuwanshi wrote:
I am testing postgres_fdw join pushdown feature for PostgreSQL 9.6 DB,
and I observed below issue._
Observation:_ Inner join and full outer join combination on a table
generating wrong result.
SELECT * FROM lt;
c1
----
1
2
(2 rows)
SELECT * FROM ft;
c1
----
1
2
(2 rows)
\d+ ft
Foreign table "public.ft"
Column | Type | Modifiers | FDW Options | Storage | Stats target |
Description
--------+---------+-----------+-------------+---------+--------------+-------------
c1 | integer | | | plain | |
Server: link_server
FDW Options: (table_name 'lt')
--inner join and full outer join on local tables
SELECT t1.c1,t2.c1,t3.c1 FROM lt t1 INNER JOIN lt t2 ON (t1.c1 = t2.c1)
FULL JOIN lt t3 ON (t2.c1 = t3.c1);
c1 | c1 | c1
----+----+----
1 | 1 | 1
2 | 2 | 2
(2 rows)
--inner join and full outer join on corresponding foreign tables
SELECT t1.c1,t2.c1,t3.c1 FROM ft t1 INNER JOIN ft t2 ON (t1.c1 = t2.c1)
FULL JOIN ft t3 ON (t2.c1 = t3.c1);
c1 | c1 | c1
----+----+----
1 | 1 | 1
1 | 2 |
2 | 1 |
2 | 2 | 2
(4 rows)
I think the reason for that is in foreign_join_ok. This in that function:
switch (jointype)
{
case JOIN_INNER:
fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
list_copy(fpinfo_i->remote_conds));
fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
list_copy(fpinfo_o->remote_conds));
break;
case JOIN_LEFT:
fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
list_copy(fpinfo_i->remote_conds));
fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
list_copy(fpinfo_o->remote_conds));
break;
case JOIN_RIGHT:
fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
list_copy(fpinfo_o->remote_conds));
fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
list_copy(fpinfo_i->remote_conds));
break;
case JOIN_FULL:
fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
list_copy(fpinfo_i->remote_conds));
fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
list_copy(fpinfo_o->remote_conds));
break;
default:
/* Should not happen, we have just check this above */
elog(ERROR, "unsupported join type %d", jointype);
}
wrongly pulls up remote_conds from joining relations in the FULL JOIN
case. I think we should not pull up such conditions in the FULL JOIN case.
Best regards,
Etsuro Fujita
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