pgsql_fdw_pushdown_v1.patch
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Filename: pgsql_fdw_pushdown_v1.patch
Type: text/plain
Part: 2
Patch
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Format: unified
Series: patch v1
| File | + | − |
|---|---|---|
| contrib/pgsql_fdw/deparse.c | 0 | 0 |
| contrib/pgsql_fdw/expected/pgsql_fdw.out | 0 | 0 |
| doc/src/sgml/pgsql-fdw.sgml | 0 | 0 |
| src/backend/nodes/nodeFuncs.c | 0 | 0 |
| src/include/nodes/nodeFuncs.h | 0 | 0 |
diff --git a/contrib/pgsql_fdw/deparse.c b/contrib/pgsql_fdw/deparse.c
index def5cb3..26b410d 100644
*** a/contrib/pgsql_fdw/deparse.c
--- b/contrib/pgsql_fdw/deparse.c
*************** typedef struct foreign_executable_cxt
*** 35,43 ****
RelOptInfo *foreignrel;
} foreign_executable_cxt;
/*
* Deparse query representation into SQL statement which suits for remote
! * PostgreSQL server.
*/
char *
deparseSql(Oid relid, PlannerInfo *root, RelOptInfo *baserel)
--- 35,48 ----
RelOptInfo *foreignrel;
} foreign_executable_cxt;
+ static bool is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel, Expr *expr);
+ static bool foreign_expr_walker(Node *node, foreign_executable_cxt *context);
+ static bool is_builtin(Oid procid);
+
/*
* Deparse query representation into SQL statement which suits for remote
! * PostgreSQL server. Also some of quals in WHERE clause will be pushed down
! * If they are safe to be evaluated on the remote side.
*/
char *
deparseSql(Oid relid, PlannerInfo *root, RelOptInfo *baserel)
*************** deparseSql(Oid relid, PlannerInfo *root,
*** 51,56 ****
--- 56,62 ----
const char *relname = NULL; /* plain relation name */
const char *q_nspname; /* quoted namespace name */
const char *q_relname; /* quoted relation name */
+ List *foreign_expr = NIL; /* list of Expr* evaluated on remote */
int i;
List *rtable = NIL;
List *context = NIL;
*************** deparseSql(Oid relid, PlannerInfo *root,
*** 59,65 ****
initStringInfo(&foreign_relname);
/*
! * First of all, determine which column should be retrieved for this scan.
*
* We do this before deparsing SELECT clause because attributes which are
* not used in neither reltargetlist nor baserel->baserestrictinfo, quals
--- 65,79 ----
initStringInfo(&foreign_relname);
/*
! * First of all, determine which qual can be pushed down.
! *
! * The expressions which satisfy is_foreign_expr() are deparsed into WHERE
! * clause of result SQL string, and they could be removed from PlanState
! * to avoid duplicate evaluation at ExecScan().
! *
! * We never change the quals in the Plan node, because this execution might
! * be for a PREPAREd statement, thus the quals in the Plan node might be
! * reused to construct another PlanState for subsequent EXECUTE statement.
*
* We do this before deparsing SELECT clause because attributes which are
* not used in neither reltargetlist nor baserel->baserestrictinfo, quals
*************** deparseSql(Oid relid, PlannerInfo *root,
*** 75,80 ****
--- 89,98 ----
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
List *attrs;
+ /* Determine whether the qual can be pushed down or not. */
+ if (is_foreign_expr(root, baserel, ri->clause))
+ foreign_expr = lappend(foreign_expr, ri->clause);
+
/*
* We need to know which attributes are used in qual evaluated
* on the local server, because they should be listed in the
*************** deparseSql(Oid relid, PlannerInfo *root,
*** 193,199 ****
--- 211,408 ----
*/
appendStringInfo(&sql, "FROM %s", foreign_relname.data);
+ /*
+ * deparse WHERE clause
+ */
+ if (foreign_expr != NIL)
+ {
+ Node *node;
+
+ node = (Node *) make_ands_explicit(foreign_expr);
+ appendStringInfo(&sql, " WHERE %s ",
+ deparse_expression(node, context, false, false));
+ list_free(foreign_expr);
+ foreign_expr = NIL;
+ }
+
elog(DEBUG3, "Remote SQL: %s", sql.data);
return sql.data;
}
+ /*
+ * Returns true if expr is safe to be evaluated on the foreign server.
+ */
+ static bool
+ is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel, Expr *expr)
+ {
+ foreign_executable_cxt context;
+ context.root = root;
+ context.foreignrel = baserel;
+
+ /*
+ * An expression which includes any mutable function can't be pushed down
+ * because it's result is not stable. For example, pushing now() down to
+ * remote side would cause confusion from the clock offset.
+ * If we have routine mapping infrastructure in future release, we will be
+ * able to choose function to be pushed down in finer granularity.
+ */
+ if (contain_mutable_functions((Node *) expr))
+ return false;
+
+ /*
+ * Check that the expression consists of nodes which are known as safe to
+ * be pushed down.
+ */
+ if (foreign_expr_walker((Node *) expr, &context))
+ return false;
+
+ return true;
+ }
+
+ /*
+ * Return true if node includes any node which is not known as safe to be
+ * pushed down.
+ */
+ static bool
+ foreign_expr_walker(Node *node, foreign_executable_cxt *context)
+ {
+ Oid func;
+
+ if (node == NULL)
+ return false;
+
+ /*
+ * If given expression has valid collation, it can't be pushed down bacause
+ * it might has uncompatible semantics on remote side.
+ */
+ if (exprCollation(node) != InvalidOid ||
+ exprInputCollation(node) != InvalidOid)
+ return true;
+
+ /*
+ * If return type of given expression is not built-in, it can't be pushed
+ * down bacause it might has uncompatible semantics on remote side.
+ */
+ if (!is_builtin(exprType(node)))
+ return true;
+
+ /*
+ * If function used by the expression is not built-in, it can't be pushed
+ * down bacause it might has uncompatible semantics on remote side.
+ */
+ func = exprFunction(node);
+ if (func != InvalidOid && !is_builtin(func))
+ return true;
+
+ switch (nodeTag(node))
+ {
+ case T_Const:
+ case T_BoolExpr:
+ case T_NullTest:
+ case T_DistinctExpr:
+ case T_RelabelType:
+ case T_FuncExpr:
+ /*
+ * These type of nodes are known as safe to be pushed down.
+ * Of course the subtree of the node, if any, should be checked
+ * continuously at the tail of this function.
+ */
+ break;
+ case T_Param:
+ /*
+ * Only external parameters can be pushed down.:
+ */
+ {
+ if (((Param *) node)->paramkind != PARAM_EXTERN)
+ return true;
+ }
+ break;
+ case T_ScalarArrayOpExpr:
+ /*
+ * Only built-in operators can be pushed down. In addition,
+ * underlying function must be built-in and immutable, but we don't
+ * check volatility here; such check must be done already with
+ * contain_mutable_functions.
+ */
+ {
+ ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
+
+ if (!is_builtin(oe->opno))
+ return true;
+
+ /* operands are checked later */
+ }
+ break;
+ case T_OpExpr:
+ /*
+ * Only built-in operators can be pushed down. In addition,
+ * underlying function must be built-in and immutable, but we don't
+ * check volatility here; such check must be done already with
+ * contain_mutable_functions.
+ */
+ {
+ OpExpr *oe = (OpExpr *) node;
+
+ if (!is_builtin(oe->opno))
+ return true;
+
+ /* operands are checked later */
+ }
+ break;
+ case T_Var:
+ /*
+ * Var can be pushed down if it is in the foreign table.
+ * XXX Var of other relation can be here?
+ */
+ {
+ Var *var = (Var *) node;
+ foreign_executable_cxt *f_context;
+
+ f_context = (foreign_executable_cxt *) context;
+ if (var->varno != f_context->foreignrel->relid ||
+ var->varlevelsup != 0)
+ return true;
+ }
+ break;
+ case T_ArrayRef:
+ /*
+ * ArrayRef which holds non-built-in typed elements can't be pushed
+ * down.
+ */
+ {
+ if (!is_builtin(((ArrayRef *) node)->refelemtype))
+ return true;
+ }
+ break;
+ case T_ArrayExpr:
+ /*
+ * ArrayExpr which holds non-built-in typed elements can't be pushed
+ * down.
+ */
+ {
+ if (!is_builtin(((ArrayExpr *) node)->element_typeid))
+ return true;
+ }
+ break;
+ default:
+ {
+ ereport(DEBUG3,
+ (errmsg("expression is too complex"),
+ errdetail("%s", nodeToString(node))));
+ return true;
+ }
+ break;
+ }
+
+ return expression_tree_walker(node, foreign_expr_walker, context);
+ }
+
+ /*
+ * Return true if given object is one of built-in objects.
+ */
+ static bool
+ is_builtin(Oid oid)
+ {
+ return (oid < FirstNormalObjectId);
+ }
+
diff --git a/contrib/pgsql_fdw/expected/pgsql_fdw.out b/contrib/pgsql_fdw/expected/pgsql_fdw.out
index dfac57a..2166fb4 100644
*** a/contrib/pgsql_fdw/expected/pgsql_fdw.out
--- b/contrib/pgsql_fdw/expected/pgsql_fdw.out
*************** SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.
*** 218,229 ****
-- with WHERE clause
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 = '1';
! QUERY PLAN
! ------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7
Filter: ((t1.c1 = 101) AND ((t1.c6)::text = '1'::text) AND (t1.c7 = '1'::bpchar))
! Remote SQL: DECLARE pgsql_fdw_cursor_4 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(4 rows)
SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 = '1';
--- 218,229 ----
-- with WHERE clause
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 = '1';
! QUERY PLAN
! ---------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7
Filter: ((t1.c1 = 101) AND ((t1.c6)::text = '1'::text) AND (t1.c7 = '1'::bpchar))
! Remote SQL: DECLARE pgsql_fdw_cursor_4 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 101)
(4 rows)
SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 = '1';
*************** EXPLAIN (COSTS false) SELECT * FROM ft1
*** 331,349 ****
(3 rows)
EXPLAIN (COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = abs(t1.c2);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = abs(c2))
! Remote SQL: DECLARE pgsql_fdw_cursor_20 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
EXPLAIN (COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = t1.c2;
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = c2)
! Remote SQL: DECLARE pgsql_fdw_cursor_21 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
DROP OPERATOR === (int, int) CASCADE;
--- 331,349 ----
(3 rows)
EXPLAIN (COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = abs(t1.c2);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = abs(c2))
! Remote SQL: DECLARE pgsql_fdw_cursor_20 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = abs(c2))
(3 rows)
EXPLAIN (COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = t1.c2;
! QUERY PLAN
! ---------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = c2)
! Remote SQL: DECLARE pgsql_fdw_cursor_21 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = c2)
(3 rows)
DROP OPERATOR === (int, int) CASCADE;
*************** DROP FUNCTION pgsql_fdw_abs(int);
*** 354,370 ****
-- simple join
PREPARE st1(int, int) AS SELECT t1.c3, t2.c3 FROM ft1 t1, ft2 t2 WHERE t1.c1 = $1 AND t2.c1 = $2;
EXPLAIN (COSTS false) EXECUTE st1(1, 2);
! QUERY PLAN
! -----------------------------------------------------------------------------------------------------------------------------------------
Nested Loop
-> Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_22 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, NULL, NULL, NULL, NULL FROM "S 1"."T 1"
! -> Materialize
! -> Foreign Scan on ft2 t2
! Filter: (c1 = 2)
! Remote SQL: DECLARE pgsql_fdw_cursor_23 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, NULL, NULL, NULL, NULL FROM "S 1"."T 1"
! (8 rows)
EXECUTE st1(1, 1);
c3 | c3
--- 354,369 ----
-- simple join
PREPARE st1(int, int) AS SELECT t1.c3, t2.c3 FROM ft1 t1, ft2 t2 WHERE t1.c1 = $1 AND t2.c1 = $2;
EXPLAIN (COSTS false) EXECUTE st1(1, 2);
! QUERY PLAN
! ------------------------------------------------------------------------------------------------------------------------------------------------------
Nested Loop
-> Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_22 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, NULL, NULL, NULL, NULL FROM "S 1"."T 1" WHERE ("C 1" = 1)
! -> Foreign Scan on ft2 t2
! Filter: (c1 = 2)
! Remote SQL: DECLARE pgsql_fdw_cursor_23 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, NULL, NULL, NULL, NULL FROM "S 1"."T 1" WHERE ("C 1" = 2)
! (7 rows)
EXECUTE st1(1, 1);
c3 | c3
*************** EXECUTE st1(101, 101);
*** 381,388 ****
-- subquery using stable function (can't be pushed down)
PREPARE st2(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c4) = 6) ORDER BY c1;
EXPLAIN (COSTS false) EXECUTE st2(10, 20);
! QUERY PLAN
! ---------------------------------------------------------------------------------------------------------------------------------------------
Sort
Sort Key: t1.c1
-> Nested Loop
--- 380,387 ----
-- subquery using stable function (can't be pushed down)
PREPARE st2(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c4) = 6) ORDER BY c1;
EXPLAIN (COSTS false) EXECUTE st2(10, 20);
! QUERY PLAN
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
Sort Key: t1.c1
-> Nested Loop
*************** EXPLAIN (COSTS false) EXECUTE st2(10, 20
*** 390,399 ****
-> HashAggregate
-> Foreign Scan on ft2 t2
Filter: ((c1 > 10) AND (date_part('dow'::text, c4) = 6::double precision))
! Remote SQL: DECLARE pgsql_fdw_cursor_29 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, c4, NULL, NULL, NULL FROM "S 1"."T 1"
-> Foreign Scan on ft1 t1
Filter: (c1 < 20)
! Remote SQL: DECLARE pgsql_fdw_cursor_28 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(11 rows)
EXECUTE st2(10, 20);
--- 389,398 ----
-> HashAggregate
-> Foreign Scan on ft2 t2
Filter: ((c1 > 10) AND (date_part('dow'::text, c4) = 6::double precision))
! Remote SQL: DECLARE pgsql_fdw_cursor_29 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, c4, NULL, NULL, NULL FROM "S 1"."T 1" WHERE ("C 1" > 10)
-> Foreign Scan on ft1 t1
Filter: (c1 < 20)
! Remote SQL: DECLARE pgsql_fdw_cursor_28 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" < 20)
(11 rows)
EXECUTE st2(10, 20);
*************** EXECUTE st1(101, 101);
*** 411,418 ****
-- subquery using immutable function (can be pushed down)
PREPARE st3(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c5) = 6) ORDER BY c1;
EXPLAIN (COSTS false) EXECUTE st3(10, 20);
! QUERY PLAN
! ---------------------------------------------------------------------------------------------------------------------------------------------
Sort
Sort Key: t1.c1
-> Nested Loop
--- 410,417 ----
-- subquery using immutable function (can be pushed down)
PREPARE st3(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c5) = 6) ORDER BY c1;
EXPLAIN (COSTS false) EXECUTE st3(10, 20);
! QUERY PLAN
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
Sort Key: t1.c1
-> Nested Loop
*************** EXPLAIN (COSTS false) EXECUTE st3(10, 20
*** 420,429 ****
-> HashAggregate
-> Foreign Scan on ft2 t2
Filter: ((c1 > 10) AND (date_part('dow'::text, c5) = 6::double precision))
! Remote SQL: DECLARE pgsql_fdw_cursor_35 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, NULL, c5, NULL, NULL FROM "S 1"."T 1"
-> Foreign Scan on ft1 t1
Filter: (c1 < 20)
! Remote SQL: DECLARE pgsql_fdw_cursor_34 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(11 rows)
EXECUTE st3(10, 20);
--- 419,428 ----
-> HashAggregate
-> Foreign Scan on ft2 t2
Filter: ((c1 > 10) AND (date_part('dow'::text, c5) = 6::double precision))
! Remote SQL: DECLARE pgsql_fdw_cursor_35 SCROLL CURSOR FOR SELECT "C 1", NULL, c3, NULL, c5, NULL, NULL FROM "S 1"."T 1" WHERE ("C 1" > 10)
-> Foreign Scan on ft1 t1
Filter: (c1 < 20)
! Remote SQL: DECLARE pgsql_fdw_cursor_34 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" < 20)
(11 rows)
EXECUTE st3(10, 20);
*************** EXECUTE st3(20, 30);
*** 441,491 ****
-- custom plan should be chosen
PREPARE st4(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 = $1;
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_40 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_41 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_42 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_43 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_44 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_46 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1"
(3 rows)
-- cleanup
--- 440,490 ----
-- custom plan should be chosen
PREPARE st4(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 = $1;
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_40 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 1)
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_41 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 1)
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_42 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 1)
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_43 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 1)
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_44 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 1)
(3 rows)
EXPLAIN (COSTS false) EXECUTE st4(1);
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on ft1 t1
Filter: (c1 = 1)
! Remote SQL: DECLARE pgsql_fdw_cursor_46 SCROLL CURSOR FOR SELECT "C 1", c2, c3, c4, c5, c6, c7 FROM "S 1"."T 1" WHERE ("C 1" = 1)
(3 rows)
-- cleanup
diff --git a/doc/src/sgml/pgsql-fdw.sgml b/doc/src/sgml/pgsql-fdw.sgml
index 299f4b6..1715257 100644
*** a/doc/src/sgml/pgsql-fdw.sgml
--- b/doc/src/sgml/pgsql-fdw.sgml
*************** postgres=# SELECT pgsql_fdw_disconnect(s
*** 225,235 ****
</para>
<synopsis>
postgres=# EXPLAIN SELECT aid FROM pgbench_accounts WHERE abalance < 0;
! QUERY PLAN
! --------------------------------------------------------------------------------------------------------------------------
! Foreign Scan on pgbench_accounts (cost=100.00..8046.37 rows=301037 width=8)
Filter: (abalance < 0)
! Remote SQL: DECLARE pgsql_fdw_cursor_1 SCROLL CURSOR FOR SELECT aid, NULL, abalance, NULL FROM public.pgbench_accounts
(3 rows)
</synopsis>
</sect2>
--- 225,235 ----
</para>
<synopsis>
postgres=# EXPLAIN SELECT aid FROM pgbench_accounts WHERE abalance < 0;
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------------------------------------
! Foreign Scan on pgbench_accounts (cost=100.00..8798.96 rows=1 width=97)
Filter: (abalance < 0)
! Remote SQL: DECLARE pgsql_fdw_cursor_2 SCROLL CURSOR FOR SELECT aid, bid, abalance, filler FROM public.pgbench_accounts WHERE (abalance < 0)
(3 rows)
</synopsis>
</sect2>
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 48b0590..f2acd46 100644
*** a/src/backend/nodes/nodeFuncs.c
--- b/src/backend/nodes/nodeFuncs.c
*************** leftmostLoc(int loc1, int loc2)
*** 1405,1410 ****
--- 1405,1447 ----
return Min(loc1, loc2);
}
+ /*
+ * exprFunction -
+ * returns the Oid of the function used by the expression's.
+ */
+ Oid
+ exprFunction(const Node *expr)
+ {
+ Oid func;
+
+ if (!expr)
+ return InvalidOid;
+
+ switch (nodeTag(expr))
+ {
+ case T_Aggref:
+ func = ((const Aggref *) expr)->aggfnoid;
+ break;
+ case T_WindowFunc:
+ func = ((const WindowFunc *) expr)->winfnoid;
+ break;
+ case T_FuncExpr:
+ func = ((const FuncExpr *) expr)->funcid;
+ break;
+ case T_OpExpr:
+ func = ((const OpExpr *) expr)->opfuncid;
+ break;
+ case T_ScalarArrayOpExpr:
+ func = ((const ScalarArrayOpExpr *) expr)->opfuncid;
+ break;
+ case T_ArrayCoerceExpr:
+ func = ((const ArrayCoerceExpr *) expr)->elemfuncid;
+ break;
+ default:
+ func = InvalidOid;
+ }
+ return func;
+ }
/*
* Standard expression-tree walking support
diff --git a/src/include/nodes/nodeFuncs.h b/src/include/nodes/nodeFuncs.h
index 4980dd8..09d877f 100644
*** a/src/include/nodes/nodeFuncs.h
--- b/src/include/nodes/nodeFuncs.h
*************** extern void exprSetInputCollation(Node *
*** 38,43 ****
--- 38,45 ----
extern int exprLocation(const Node *expr);
+ extern Oid exprFunction(const Node *expr);
+
extern bool expression_tree_walker(Node *node, bool (*walker) (),
void *context);
extern Node *expression_tree_mutator(Node *node, Node *(*mutator) (),