On 2016/02/10 4:16, Robert Haas wrote:
On Tue, Feb 9, 2016 at 8:39 AM, Ashutosh Bapat
<ashutosh.ba...@enterprisedb.com> wrote:
Thanks Jeevan for your review and comments. PFA the patch which fixes those.

Committed with a couple more small adjustments.

Thanks for working on this, Robert, Ashutosh, and everyone involved!

I happened to notice that this code in foreign_join_ok():

    switch (jointype)
    {
        case JOIN_INNER:
            fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
                                               fpinfo_i->remote_conds);
            fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
                                               fpinfo_o->remote_conds);
            break;

        case JOIN_LEFT:
            fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
                                              fpinfo_i->remote_conds);
            fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
                                               fpinfo_o->remote_conds);
            break;

        case JOIN_RIGHT:
            fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
                                              fpinfo_o->remote_conds);
            fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
                                               fpinfo_i->remote_conds);
            break;

        case JOIN_FULL:
            fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
                                              fpinfo_i->remote_conds);
            fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
                                              fpinfo_o->remote_conds);
            break;

        default:
            /* Should not happen, we have just check this above */
            elog(ERROR, "unsupported join type %d", jointype);
    }

would break the list fpinfo_i->remote_conds in the case of INNER JOIN or FULL JOIN. You can see the list breakage from e.g., the following queries on an Assert-enabled build:

postgres=# create extension postgres_fdw;
CREATE EXTENSION
postgres=# create server myserver foreign data wrapper postgres_fdw options (dbname 'mydatabase');
CREATE SERVER
postgres=# create user mapping for current_user server myserver;
CREATE USER MAPPING
postgres=# create foreign table foo (a int) server myserver options (table_name 'foo');
CREATE FOREIGN TABLE
postgres=# create foreign table bar (a int) server myserver options (table_name 'bar');
CREATE FOREIGN TABLE
postgres=# create foreign table baz (a int) server myserver options (table_name 'baz');
CREATE FOREIGN TABLE
postgres=# select * from foo, bar, baz where foo.a = bar.a and bar.a = baz.a and foo.a < 10 and bar.a < 10 and baz.a < 10;

Attached is a patch to avoid the breakage.

Best regards,
Etsuro Fujita
*** a/contrib/postgres_fdw/postgres_fdw.c
--- b/contrib/postgres_fdw/postgres_fdw.c
***************
*** 3488,3495 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
  		case JOIN_INNER:
  			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  											   fpinfo_i->remote_conds);
! 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
! 											   fpinfo_o->remote_conds);
  			break;
  
  		case JOIN_LEFT:
--- 3488,3496 ----
  		case JOIN_INNER:
  			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  											   fpinfo_i->remote_conds);
! 			if (fpinfo_o->remote_conds)
! 				fpinfo->remote_conds = list_concat(list_copy(fpinfo->remote_conds),
! 												   fpinfo_o->remote_conds);
  			break;
  
  		case JOIN_LEFT:
***************
*** 3509,3516 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
  		case JOIN_FULL:
  			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
  											  fpinfo_i->remote_conds);
! 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
! 											  fpinfo_o->remote_conds);
  			break;
  
  		default:
--- 3510,3518 ----
  		case JOIN_FULL:
  			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
  											  fpinfo_i->remote_conds);
! 			if (fpinfo_o->remote_conds)
! 				fpinfo->joinclauses = list_concat(list_copy(fpinfo->joinclauses),
! 												  fpinfo_o->remote_conds);
  			break;
  
  		default:
-- 
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