Alexander Korotkov писал(а) 2026-05-19 16:00:
Hi, Alexander.
On Mon, May 18, 2026 at 11:06 PM Alexander Pyhalov
<[email protected]> wrote:
Hi. I am a bit confused about this comment (and code):
/*
* DirectModify on a foreign join: pass NIL/0
for
the function
* metadata. We don't currently push function
RTEs through the
* direct-modify path, so there are no
whole-row
Vars pointing at
* function-RTE tuples to reconstruct.
*/
tupdesc =
get_tupdesc_for_join_scan_tuples(node,
NIL, 0);
We evidently go through this code path when executing example
UPDATE remote_tbl r SET b=5 FROM UNNEST(array[box '((2,3),(-2,-3))'])
AS
t (bx) WHERE r.a = area(t.bx)
RETURNING a,b;
But don't need whole row var in returning list.... However, we still
can
step on this issue.
Yes, we go through this code path, and it works as long as whole-row
var is not needed.
UPDATE remote_tbl r SET b=5 FROM UNNEST(array[box '((2,3),(-2,-3))'],
array[int '1']) AS t (bx, i) WHERE r.a = area(t.bx)
RETURNING a,b,t;
ERROR: input of anonymous composite types is not implemented
CONTEXT: whole-row reference to foreign table "t"
But if whole row var is actually used, then the assumption is broken.
So, we need to build a whole-row var anyway. I've fixed this in the
attached patch, and added your sample query as a regression test case.
Good evening.
Found one more issue in whole row var deparsing. It can appear on a
nullable outer side, and we should use the same logic as when deparsing
table column reference. Otherwise we get records from nulls instead of
nulls (for example, "(NULL, NULL)" instead of NULL).
Also I wonder if it is possible for get_tupdesc_for_join_scan_tuples()
to get NULL rtfuncdata when it looks at RTE_FUNCTION RTE here:
1759 else if (rte->rtekind == RTE_FUNCTION && rtfuncdata
!= NIL)
1760 {
1761 /*
1762 * A whole-row Var points at a FUNCTION RTE
absorbed into the
1763 * foreign join. Synthesize an anonymous
composite TupleDesc from
1764 * the per-function return-type metadata we
saved at plan time;
1765 * the deparser emits these as
ROW(f<rti>.c1, f<rti>.c2, ...).
1766 */
1767 List *funcdata;
1768 TupleDesc rte_tupdesc;
1769 int num_funcs;
1770 int attnum;
1771 ListCell *lc1,
?
--
Best regards,
Alexander Pyhalov,
Postgres Professional
From 2b78decae1c0d333ca04bd1394012f43cb14aea3 Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <[email protected]>
Date: Tue, 19 May 2026 16:28:22 +0300
Subject: [PATCH] postgres_fdw: push down FUNCTION RTE into foreign joins
A foreign join planning hook now considers a (foreign-table x function-RTE)
INNER join as a push-down candidate when the function expression is
IMMUTABLE and otherwise shippable. The remote query absorbs the function
call as a FROM-list item (e.g. unnest(...) AS f<rti>(c1, c2, ...)), so the
foreign side returns only rows that match the function-produced set and the
join executes entirely on the remote.
An IMMUTABLE function gives the same result on any server, so the same
function RTE can be a push-down candidate for several distinct foreign
servers without semantic risk. To keep the planner state consistent
across those independent attempts, the per-call stub fpinfo for the
function side lives on the joinrel's PgFdwRelationInfo (new
outer_func_fpinfo / inner_func_fpinfo), never on the function rel itself,
and the function side is detected via rtekind rather than fdw_private.
set_foreign_rel_properties() propagates fdwroutine onto a joinrel that
pairs a foreign rel with an RTE_FUNCTION rel so GetForeignJoinPaths gets
called; the FDW retains full control over whether to actually generate a
path. deparseRangeTblRef and deparseColumnRef gain a FUNCTION-RTE branch
that emits the function expression and resolves Vars to the generated
column aliases.
---
contrib/postgres_fdw/deparse.c | 132 ++++-
.../postgres_fdw/expected/postgres_fdw.out | 441 +++++++++++++++++
contrib/postgres_fdw/postgres_fdw.c | 455 +++++++++++++++++-
contrib/postgres_fdw/postgres_fdw.h | 10 +
contrib/postgres_fdw/sql/postgres_fdw.sql | 183 +++++++
src/backend/optimizer/util/relnode.c | 24 +
6 files changed, 1221 insertions(+), 24 deletions(-)
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index 2dcc6c8af1b..5567fdb8ed9 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -112,6 +112,7 @@ typedef struct deparse_expr_cxt
appendStringInfo((buf), "%s%d.", REL_ALIAS_PREFIX, (varno))
#define SUBQUERY_REL_ALIAS_PREFIX "s"
#define SUBQUERY_COL_ALIAS_PREFIX "c"
+#define FUNCTION_REL_ALIAS_PREFIX "f"
/*
* Functions to determine whether an expression can be evaluated safely on
@@ -2030,6 +2031,72 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
}
}
+/*
+ * Deparse a FUNCTION RTE absorbed into a foreign join. The function call(s)
+ * are emitted as a FROM-list item:
+ *
+ * <funcexpr> AS f<rti>(c1, c2, ..., cN)
+ *
+ * For multi-function RTEs (SQL ROWS FROM (f1(), f2(), ...)), each
+ * function call appears comma-separated inside ROWS FROM(...). Column
+ * aliases c1..cN cover the union of every function's columns, in the
+ * order they appear; that matches the column ordering of the RTE.
+ */
+static void
+deparseFunctionRangeTblRef(StringInfo buf, PlannerInfo *root,
+ RelOptInfo *foreignrel, RelOptInfo *scanrel,
+ List **params_list)
+{
+ RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
+ deparse_expr_cxt context;
+ ListCell *lc;
+ bool multi_func;
+ int total_cols = 0;
+ int i;
+
+ Assert(rte->rtekind == RTE_FUNCTION);
+ Assert(!rte->funcordinality);
+ Assert(list_length(rte->functions) >= 1);
+
+ multi_func = list_length(rte->functions) > 1;
+
+ context.buf = buf;
+ context.root = root;
+ context.foreignrel = scanrel;
+ context.scanrel = scanrel;
+ context.params_list = params_list;
+
+ if (multi_func)
+ appendStringInfoString(buf, "ROWS FROM (");
+
+ foreach(lc, rte->functions)
+ {
+ RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
+
+ if (foreach_current_index(lc) > 0)
+ appendStringInfoString(buf, ", ");
+ deparseExpr((Expr *) rtfunc->funcexpr, &context);
+ total_cols += rtfunc->funccolcount;
+ }
+
+ if (multi_func)
+ appendStringInfoChar(buf, ')');
+
+ /* Alias + generated column-name list. */
+ appendStringInfo(buf, " %s%d", FUNCTION_REL_ALIAS_PREFIX, foreignrel->relid);
+ if (total_cols > 0)
+ {
+ appendStringInfoChar(buf, '(');
+ for (i = 1; i <= total_cols; i++)
+ {
+ if (i > 1)
+ appendStringInfoString(buf, ", ");
+ appendStringInfo(buf, "%s%d", SUBQUERY_COL_ALIAS_PREFIX, i);
+ }
+ appendStringInfoChar(buf, ')');
+ }
+}
+
/*
* Append FROM clause entry for the given relation into buf.
* Conditions from lower-level SEMI-JOINs are appended to additional_conds
@@ -2040,7 +2107,22 @@ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
bool make_subquery, Index ignore_rel, List **ignore_conds,
List **additional_conds, List **params_list)
{
- PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+ PgFdwRelationInfo *fpinfo;
+
+ /*
+ * For a function RTE absorbed into a foreign join, deparse the function
+ * expression as a FROM-list item and return. The stub fpinfo set up by
+ * foreign_join_ok() may or may not be present here.
+ */
+ if (foreignrel->rtekind == RTE_FUNCTION)
+ {
+ Assert(!make_subquery);
+ deparseFunctionRangeTblRef(buf, root, foreignrel, foreignrel,
+ params_list);
+ return;
+ }
+
+ fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
/* Should only be called in these cases. */
Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
@@ -2712,6 +2794,54 @@ static void
deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte,
bool qualify_col)
{
+ /*
+ * Function RTE columns: emit as f<varno>.c<varattno>, matching the
+ * aliases generated by deparseFunctionRangeTblRef(). A whole-row Var
+ * (varattno == 0) is rendered as ROW(f<varno>.c1, ..., f<varno>.c<N>)
+ * where N is the total column count of the function RTE (including all
+ * ROWS FROM (...) members). System attributes such as ctid have no
+ * meaning for function RTEs and are rejected.
+ */
+ if (rte->rtekind == RTE_FUNCTION)
+ {
+ if (varattno == 0)
+ {
+ int ncols = list_length(rte->eref->colnames);
+ int i;
+
+ if (qualify_col)
+ {
+ appendStringInfoString(buf, "CASE WHEN (");
+ appendStringInfo(buf, "%s%d.", FUNCTION_REL_ALIAS_PREFIX, varno);
+ appendStringInfoString(buf, "*)::text IS NOT NULL THEN ");
+ }
+
+ appendStringInfoString(buf, "ROW(");
+ for (i = 1; i <= ncols; i++)
+ {
+ if (i > 1)
+ appendStringInfoString(buf, ", ");
+ appendStringInfo(buf, "%s%d.%s%d",
+ FUNCTION_REL_ALIAS_PREFIX, varno,
+ SUBQUERY_COL_ALIAS_PREFIX, i);
+ }
+ appendStringInfoChar(buf, ')');
+
+ if (qualify_col)
+ appendStringInfoString(buf, " END");
+ return;
+ }
+
+ if (varattno < 0)
+ elog(ERROR,
+ "system attribute reference to a function RTE is not supported in foreign join pushdown");
+
+ if (qualify_col)
+ appendStringInfo(buf, "%s%d.", FUNCTION_REL_ALIAS_PREFIX, varno);
+ appendStringInfo(buf, "%s%d", SUBQUERY_COL_ALIAS_PREFIX, varattno);
+ return;
+ }
+
/* We support fetching the remote side's CTID and OID. */
if (varattno == SelfItemPointerAttributeNumber)
{
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index aaffcf31271..c21d0876d39 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2885,6 +2885,447 @@ SELECT t1.c1, t2.c2 FROM v4 t1 LEFT JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c
(10 rows)
ALTER VIEW v4 OWNER TO regress_view_owner;
+-- ===================================================================
+-- Foreign-join with FUNCTION RTE pushdown (IMMUTABLE functions only)
+-- ===================================================================
+-- IMMUTABLE function: unnest of constant array can be pushed down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t1.c3 FROM ft1 t1, unnest(ARRAY[1, 5, 10, 100]::int[]) AS u(id)
+WHERE t1.c1 = u.id ORDER BY t1.c1;
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------------
+ Sort
+ Output: t1.c1, t1.c3
+ Sort Key: t1.c1
+ -> Foreign Scan
+ Output: t1.c1, t1.c3
+ Relations: (public.ft1 t1) INNER JOIN (Function u)
+ Remote SQL: SELECT r1."C 1", r1.c3 FROM ("S 1"."T 1" r1 INNER JOIN unnest('{1,5,10,100}'::integer[]) f2(c1) ON (((r1."C 1" = f2.c1))))
+(7 rows)
+
+SELECT t1.c1, t1.c3 FROM ft1 t1, unnest(ARRAY[1, 5, 10, 100]::int[]) AS u(id)
+WHERE t1.c1 = u.id ORDER BY t1.c1;
+ c1 | c3
+-----+-------
+ 1 | 00001
+ 5 | 00005
+ 10 | 00010
+ 100 | 00100
+(4 rows)
+
+-- IMMUTABLE function: generate_series with constant args
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1 FROM ft1 t1, generate_series(1, 4) AS g(id)
+WHERE t1.c1 = g.id ORDER BY t1.c1;
+ QUERY PLAN
+-----------------------------------------------------------------------------------------------------------------------------
+ Sort
+ Output: t1.c1
+ Sort Key: t1.c1
+ -> Foreign Scan
+ Output: t1.c1
+ Relations: (public.ft1 t1) INNER JOIN (Function g)
+ Remote SQL: SELECT r1."C 1" FROM ("S 1"."T 1" r1 INNER JOIN generate_series(1, 4) f2(c1) ON (((r1."C 1" = f2.c1))))
+(7 rows)
+
+SELECT t1.c1 FROM ft1 t1, generate_series(1, 4) AS g(id)
+WHERE t1.c1 = g.id ORDER BY t1.c1;
+ c1
+----
+ 1
+ 2
+ 3
+ 4
+(4 rows)
+
+-- VOLATILE function (random) must NOT be pushed down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1 FROM ft1 t1, generate_series(1, 4 + (random() * 0)::int) AS g(id)
+WHERE t1.c1 = g.id;
+ QUERY PLAN
+------------------------------------------------------------------------------------------------
+ Hash Join
+ Output: t1.c1
+ Hash Cond: (g.id = t1.c1)
+ -> Function Scan on pg_catalog.generate_series g
+ Output: g.id
+ Function Call: generate_series(1, (4 + ((random() * '0'::double precision))::integer))
+ -> Hash
+ Output: t1.c1
+ -> Foreign Scan on public.ft1 t1
+ Output: t1.c1
+ Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+(11 rows)
+
+-- WITH ORDINALITY must NOT be pushed down (limitation of this implementation)
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, u.ord
+FROM ft1 t1, unnest(ARRAY[1, 5, 10]::int[]) WITH ORDINALITY AS u(id, ord)
+WHERE t1.c1 = u.id;
+ QUERY PLAN
+------------------------------------------------------------
+ Hash Join
+ Output: t1.c1, u.ord
+ Hash Cond: (t1.c1 = u.id)
+ -> Foreign Scan on public.ft1 t1
+ Output: t1.c1
+ Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+ -> Hash
+ Output: u.ord, u.id
+ -> Function Scan on pg_catalog.unnest u
+ Output: u.ord, u.id
+ Function Call: unnest('{1,5,10}'::integer[])
+(11 rows)
+
+-- Same function RTE joined with two different foreign servers: planner picks
+-- one absorption + a local join with the second foreign server. The fact
+-- that the function is IMMUTABLE makes this safe even if both sides chose to
+-- absorb it independently.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1
+FROM ft1 t1, ft6 t2, unnest(ARRAY[1, 5, 10, 100]::int[]) AS u(id)
+WHERE t1.c1 = u.id AND t2.c1 = u.id ORDER BY t1.c1;
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------------
+ Merge Join
+ Output: t1.c1, t2.c1
+ Merge Cond: (t1.c1 = u.id)
+ -> Foreign Scan on public.ft1 t1
+ Output: t1.c1
+ Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC NULLS LAST
+ -> Sort
+ Output: t2.c1, u.id
+ Sort Key: t2.c1
+ -> Foreign Scan
+ Output: t2.c1, u.id
+ Relations: (public.ft6 t2) INNER JOIN (Function u)
+ Remote SQL: SELECT r2.c1, f3.c1 FROM ("S 1"."T 4" r2 INNER JOIN unnest('{1,5,10,100}'::integer[]) f3(c1) ON (((r2.c1 = f3.c1))))
+(13 rows)
+
+-- Cost-based selection between two foreign servers: ft1 ("S 1"."T 1") has
+-- 1000 rows, ft6 ("S 1"."T 4") has ~33 rows. The same query shape gets a
+-- different push-down target depending on a predicate that changes the
+-- effective cardinality of one side -- the function "jumps" to whichever
+-- foreign scan benefits more from being pre-filtered.
+ANALYZE ft1;
+ANALYZE ft6;
+-- No extra predicate: ft1 is the bigger side, function absorbed there.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1
+FROM ft1 t1, ft6 t2, unnest(ARRAY[3, 6, 9, 12, 15, 18]::int[]) AS u(id)
+WHERE t1.c1 = u.id AND t2.c1 = u.id;
+ QUERY PLAN
+----------------------------------------------------------------------------------------------------------------------------------------------------
+ Hash Join
+ Output: t1.c1, t2.c1
+ Hash Cond: (t1.c1 = t2.c1)
+ -> Foreign Scan
+ Output: t1.c1, u.id
+ Relations: (public.ft1 t1) INNER JOIN (Function u)
+ Remote SQL: SELECT r1."C 1", f3.c1 FROM ("S 1"."T 1" r1 INNER JOIN unnest('{3,6,9,12,15,18}'::integer[]) f3(c1) ON (((r1."C 1" = f3.c1))))
+ -> Hash
+ Output: t2.c1
+ -> Foreign Scan on public.ft6 t2
+ Output: t2.c1
+ Remote SQL: SELECT c1 FROM "S 1"."T 4"
+(12 rows)
+
+-- Selective predicate on ft1.c3 (not in the eqclass) shrinks ft1 to a
+-- handful of remote rows; now ft6 is effectively the bigger side and the
+-- function is absorbed into ft6 instead.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1
+FROM ft1 t1, ft6 t2, unnest(ARRAY[3, 6, 9, 12, 15, 18]::int[]) AS u(id)
+WHERE t1.c1 = u.id AND t2.c1 = u.id AND t1.c3 < '00010';
+ QUERY PLAN
+----------------------------------------------------------------------------------------------------------------------------------------------------
+ Nested Loop
+ Output: t1.c1, t2.c1
+ Join Filter: (t1.c1 = u.id)
+ -> Foreign Scan on public.ft1 t1
+ Output: t1.c1
+ Remote SQL: SELECT "C 1" FROM "S 1"."T 1" WHERE ((c3 < '00010'))
+ -> Materialize
+ Output: t2.c1, u.id
+ -> Foreign Scan
+ Output: t2.c1, u.id
+ Relations: (public.ft6 t2) INNER JOIN (Function u)
+ Remote SQL: SELECT r2.c1, f3.c1 FROM ("S 1"."T 4" r2 INNER JOIN unnest('{3,6,9,12,15,18}'::integer[]) f3(c1) ON (((r2.c1 = f3.c1))))
+(12 rows)
+
+-- The remaining scenarios reuse a dedicated foreign table to cover the
+-- corner cases of FUNCTION RTE push-down: function-first FROM, record
+-- return type rejection, whole-row reference, UPDATE...FROM..., and
+-- multi-function ROWS FROM.
+CREATE TABLE base_tbl_fn (a int, b int);
+INSERT INTO base_tbl_fn
+ SELECT g, g + 100 FROM generate_series(1, 30) g;
+CREATE FOREIGN TABLE remote_tbl (a int, b int)
+ SERVER loopback OPTIONS (table_name 'base_tbl_fn');
+-- The function RTE appears first in FROM; the foreign relation must be
+-- found by scanning fs_base_relids for an RTE_RELATION rather than
+-- using scan->fs_relid blindly.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n;
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan
+ Output: n.n, r.a, r.b
+ Relations: (Function n) INNER JOIN (public.remote_tbl r)
+ Remote SQL: SELECT f1.c1, r2.a, r2.b FROM (unnest('{2,3,4}'::integer[]) f1(c1) INNER JOIN public.base_tbl_fn r2 ON (((f1.c1 = r2.a))))
+(4 rows)
+
+SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
+WHERE r.a = n ORDER BY r.a;
+ n | a | b
+---+---+-----
+ 2 | 2 | 102
+ 3 | 3 | 103
+ 4 | 4 | 104
+(3 rows)
+
+-- A function returning record (composite) is forbidden; pushing it
+-- would yield a remote "column definition list is required" error.
+-- function_rte_pushdown_ok() rejects it via TYPEFUNC_SCALAR.
+CREATE OR REPLACE FUNCTION f_ret_record() RETURNS record AS $$
+ SELECT (1, 2)::record
+$$ LANGUAGE SQL IMMUTABLE;
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT s FROM remote_tbl rt, f_ret_record() AS s(a int, b int)
+WHERE s.a = rt.a;
+ QUERY PLAN
+------------------------------------------------------
+ Hash Join
+ Output: s.*
+ Hash Cond: (rt.a = s.a)
+ -> Foreign Scan on public.remote_tbl rt
+ Output: rt.a, rt.b
+ Remote SQL: SELECT a FROM public.base_tbl_fn
+ -> Hash
+ Output: s.*, s.a
+ -> Function Scan on public.f_ret_record s
+ Output: s.*, s.a
+ Function Call: f_ret_record()
+(11 rows)
+
+DROP FUNCTION f_ret_record();
+-- UPDATE ... FROM unnest() with a complex element type; area(box)
+-- yields the value to match. The locking machinery for the
+-- non-relation RTE generates a whole-row Var that deparseColumnRef
+-- emits as ROW(f<rti>.c1, ...).
+UPDATE remote_tbl r SET b = 999
+FROM unnest(array[box '((2,3),(-2,-3))']) AS t(bx)
+WHERE r.a = area(t.bx);
+SELECT * FROM remote_tbl WHERE a IN (23, 24, 25) ORDER BY a;
+ a | b
+----+-----
+ 23 | 123
+ 24 | 999
+ 25 | 125
+(3 rows)
+
+-- The same shape with CASE and RETURNING; exercises the DirectModify
+-- path and the executor's tuple-desc reconstruction.
+UPDATE remote_tbl r
+ SET b = CASE WHEN random() >= 0 THEN 5 ELSE 0 END
+ FROM unnest(array[box '((2,3),(-2,-3))']) AS t(bx)
+ WHERE r.a = area(t.bx) RETURNING a, b;
+ a | b
+----+---
+ 24 | 5
+(1 row)
+
+-- RETURNING a whole-row reference to the function RTE. Without the
+-- per-RTE function metadata being preserved on the DirectModify path
+-- (FdwDirectModifyPrivateFunctions / FdwDirectModifyPrivateMinRTIndex),
+-- this would fail with "input of anonymous composite types is not
+-- implemented".
+UPDATE remote_tbl r SET b = 7
+ FROM unnest(array[box '((2,3),(-2,-3))'],
+ array[int '1']) AS t(bx, i)
+ WHERE r.a = area(t.bx) RETURNING a, b, t;
+ a | b | t
+----+---+---------------------
+ 24 | 7 | ("(2,3),(-2,-3)",1)
+(1 row)
+
+-- ROWS FROM (...) with several functions. Force pushdown because the
+-- cost model otherwise picks a local plan.
+SET enable_hashjoin = off;
+SET enable_mergejoin = off;
+SET enable_nestloop = off;
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a, t.n, t.s
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Sort
+ Output: r.a, t.n, t.s
+ Sort Key: r.a
+ -> Foreign Scan
+ Output: r.a, t.n, t.s
+ Relations: (public.remote_tbl r) INNER JOIN (Function t)
+ Remote SQL: SELECT r1.a, f2.c1, f2.c2 FROM (public.base_tbl_fn r1 INNER JOIN ROWS FROM (unnest('{3,6,9}'::integer[]), generate_series(11, 13)) f2(c1, c2) ON (((r1.a = f2.c1))))
+(7 rows)
+
+SELECT r.a, t.n, t.s
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+ a | n | s
+---+---+----
+ 3 | 3 | 11
+ 6 | 6 | 12
+ 9 | 9 | 13
+(3 rows)
+
+-- Whole-row Var on the absorbed function side (e.g. via a cast to
+-- text). Exercises both deparseColumnRef whole-row branch and the
+-- get_tupdesc_for_join_scan_tuples() RTE_FUNCTION metadata path.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t::text, r.a
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+ QUERY PLAN
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Sort
+ Output: ((t.*)::text), r.a
+ Sort Key: r.a
+ -> Foreign Scan
+ Output: (t.*)::text, r.a
+ Relations: (public.remote_tbl r) INNER JOIN (Function t)
+ Remote SQL: SELECT CASE WHEN (f2.*)::text IS NOT NULL THEN ROW(f2.c1, f2.c2) END, r1.a FROM (public.base_tbl_fn r1 INNER JOIN ROWS FROM (unnest('{3,6,9}'::integer[]), generate_series(11, 13)) f2(c1, c2) ON (((r1.a = f2.c1))))
+(7 rows)
+
+SELECT t::text, r.a
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+ t | a
+--------+---
+ (3,11) | 3
+ (6,12) | 6
+ (9,13) | 9
+(3 rows)
+
+-- Check whole-row Var represented by function on the nullable
+-- left join side
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT u, ft5.c1, ft5.c2, ft4.c1, ft4.c2 FROM ft5 LEFT JOIN
+(ft4 JOIN unnest(array[1,2], array[3,4]) as u (u1, u2) ON ft4.c1=u1)
+ON ft5.c1 = ft4.c1 WHERE ft5.c1 < 10 ORDER BY ft5.c1;
+ QUERY PLAN
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan
+ Output: u.*, ft5.c1, ft5.c2, ft4.c1, ft4.c2
+ Relations: (public.ft5) LEFT JOIN ((public.ft4) INNER JOIN (Function u))
+ Remote SQL: SELECT CASE WHEN (f3.*)::text IS NOT NULL THEN ROW(f3.c1, f3.c2) END, r1.c1, r1.c2, r2.c1, r2.c2 FROM ("S 1"."T 4" r1 LEFT JOIN ("S 1"."T 3" r2 INNER JOIN ROWS FROM (unnest('{1,2}'::integer[]), unnest('{3,4}'::integer[])) f3(c1, c2) ON (((r2.c1 = f3.c1)))) ON (((r1.c1 = r2.c1)))) WHERE ((r1.c1 < 10)) ORDER BY r1.c1 ASC NULLS LAST
+(4 rows)
+
+SELECT u, ft5.c1, ft5.c2, ft4.c1, ft4.c2 FROM ft5 LEFT JOIN
+(ft4 JOIN unnest(array[1,2], array[3,4]) as u (u1, u2) ON ft4.c1=u1)
+ON ft5.c1 = ft4.c1 WHERE ft5.c1 < 10 ORDER BY ft5.c1;
+ u | c1 | c2 | c1 | c2
+---+----+----+----+----
+ | 3 | 4 | |
+ | 6 | 7 | |
+ | 9 | 10 | |
+(3 rows)
+
+RESET enable_hashjoin;
+RESET enable_mergejoin;
+RESET enable_nestloop;
+-- Volatile function in ROWS FROM disqualifies the whole RTE.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a FROM remote_tbl r,
+ ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(1, 4 + (random() * 0)::int)) AS t(n, s)
+ WHERE r.a = t.n;
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------
+ Merge Join
+ Output: r.a
+ Merge Cond: (t.n = r.a)
+ -> Sort
+ Output: t.n
+ Sort Key: t.n
+ -> Function Scan on t
+ Output: t.n
+ Function Call: unnest('{3,6,9}'::integer[]), generate_series(1, (4 + ((random() * '0'::double precision))::integer))
+ -> Sort
+ Output: r.a
+ Sort Key: r.a
+ -> Foreign Scan on public.remote_tbl r
+ Output: r.a
+ Remote SQL: SELECT a FROM public.base_tbl_fn
+(15 rows)
+
+-- LATERAL function referencing a foreign Var: postgres_fdw's
+-- foreign-join pushdown rejects this via the joinrel->lateral_relids
+-- check; the plan is therefore a local NestLoop + FunctionScan.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a, t.x FROM remote_tbl r, LATERAL unnest(array[r.a]) AS t(x)
+WHERE r.a <= 3 ORDER BY r.a;
+ QUERY PLAN
+-------------------------------------------------------------------------------------------------
+ Nested Loop
+ Output: r.a, t.x
+ -> Foreign Scan on public.remote_tbl r
+ Output: r.a, r.b
+ Remote SQL: SELECT a FROM public.base_tbl_fn WHERE ((a <= 3)) ORDER BY a ASC NULLS LAST
+ -> Function Scan on pg_catalog.unnest t
+ Output: t.x
+ Function Call: unnest(ARRAY[r.a])
+(8 rows)
+
+-- Outer joins with the function RTE are not pushed down (only INNER
+-- joins are supported by function_rte_pushdown_ok()).
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a, t.n FROM remote_tbl r
+ LEFT JOIN unnest(array[1, 2, 3]) AS t(n) ON r.a = t.n
+ WHERE r.a <= 5 ORDER BY r.a;
+ QUERY PLAN
+-------------------------------------------------------------------------------------------------
+ Merge Left Join
+ Output: r.a, t.n
+ Merge Cond: (r.a = t.n)
+ -> Foreign Scan on public.remote_tbl r
+ Output: r.a, r.b
+ Remote SQL: SELECT a FROM public.base_tbl_fn WHERE ((a <= 5)) ORDER BY a ASC NULLS LAST
+ -> Sort
+ Output: t.n
+ Sort Key: t.n
+ -> Function Scan on pg_catalog.unnest t
+ Output: t.n
+ Function Call: unnest('{1,2,3}'::integer[])
+(12 rows)
+
+-- SEMI join (EXISTS) with a function RTE is also not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a FROM remote_tbl r
+ WHERE EXISTS (SELECT 1 FROM unnest(array[3, 6, 9]) AS t(n) WHERE t.n = r.a)
+ ORDER BY r.a;
+ QUERY PLAN
+--------------------------------------------------------------------------------
+ Merge Semi Join
+ Output: r.a
+ Merge Cond: (r.a = t.n)
+ -> Foreign Scan on public.remote_tbl r
+ Output: r.a, r.b
+ Remote SQL: SELECT a FROM public.base_tbl_fn ORDER BY a ASC NULLS LAST
+ -> Sort
+ Output: t.n
+ Sort Key: t.n
+ -> Function Scan on pg_catalog.unnest t
+ Output: t.n
+ Function Call: unnest('{3,6,9}'::integer[])
+(12 rows)
+
+DROP FOREIGN TABLE remote_tbl;
+DROP TABLE base_tbl_fn;
-- ====================================================================
-- Check that userid to use when querying the remote table is correctly
-- propagated into foreign rels present in subqueries under an UNION ALL
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 0ff4ec23164..dc552a847d8 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -31,6 +31,7 @@
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/appendinfo.h"
+#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/inherit.h"
#include "optimizer/optimizer.h"
@@ -88,6 +89,22 @@ enum FdwScanPrivateIndex
* of join, added when the scan is join
*/
FdwScanPrivateRelations,
+
+ /*
+ * List of per-RTE function metadata, indexed by base RTI offset. Each
+ * element is either NULL (for non-RTE_FUNCTION rels in this scan) or a
+ * list of three-element lists (funcid, funcrettype, funccollation) -- one
+ * inner list per function in the RTE. Allows the executor to rebuild
+ * TupleDesc entries for whole-row references to function RTEs.
+ */
+ FdwScanPrivateFunctions,
+
+ /*
+ * Integer node: minimum base RT index covered by the scan, used to
+ * translate scan-local indexes to estate-rtable indexes after setrefs.c
+ * flattens rtables.
+ */
+ FdwScanPrivateMinRTIndex,
};
/*
@@ -124,6 +141,11 @@ enum FdwModifyPrivateIndex
* 2) Boolean flag showing if the remote query has a RETURNING clause
* 3) Integer list of attribute numbers retrieved by RETURNING, if any
* 4) Boolean flag showing if we set the command es_processed
+ * 5) Per-RTE function metadata (mirrors FdwScanPrivateFunctions; lets
+ * the executor rebuild TupleDesc entries for whole-row Vars over
+ * function RTEs absorbed into a foreign join)
+ * 6) Integer node: minimum base RT index of the scan (mirrors
+ * FdwScanPrivateMinRTIndex)
*/
enum FdwDirectModifyPrivateIndex
{
@@ -135,6 +157,10 @@ enum FdwDirectModifyPrivateIndex
FdwDirectModifyPrivateRetrievedAttrs,
/* set-processed flag (as a Boolean node) */
FdwDirectModifyPrivateSetProcessed,
+ /* Per-RTE function metadata, indexed by base RTI offset */
+ FdwDirectModifyPrivateFunctions,
+ /* Integer node: minimum base RT index in the scan */
+ FdwDirectModifyPrivateMinRTIndex,
};
/*
@@ -740,6 +766,9 @@ static bool foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
RelOptInfo *rel);
static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
+static Relids get_base_relids(PlannerInfo *root, RelOptInfo *rel);
+static int get_min_base_rti(PlannerInfo *root, RelOptInfo *rel);
+static List *get_functions_data(PlannerInfo *root, RelOptInfo *rel);
static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
Path *epq_path, List *restrictlist);
static void add_foreign_grouping_paths(PlannerInfo *root,
@@ -1634,9 +1663,26 @@ postgresGetForeignPlan(PlannerInfo *root,
fdw_private = list_make3(makeString(sql.data),
retrieved_attrs,
makeInteger(fpinfo->fetch_size));
+
+ /*
+ * Position FdwScanPrivateRelations: either the EXPLAIN relation string
+ * (joins/upper rels) or a NULL placeholder, so that subsequent indexes
+ * stay valid for the base-rel scan case.
+ */
if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
fdw_private = lappend(fdw_private,
makeString(fpinfo->relation_name));
+ else
+ fdw_private = lappend(fdw_private, NULL);
+
+ /*
+ * FdwScanPrivateFunctions / FdwScanPrivateMinRTIndex carry the metadata
+ * the executor needs to rebuild TupleDesc entries for whole-row Vars
+ * pointing at RTE_FUNCTION rels absorbed into the foreign scan.
+ */
+ fdw_private = lappend(fdw_private, get_functions_data(root, foreignrel));
+ fdw_private = lappend(fdw_private,
+ makeInteger(get_min_base_rti(root, foreignrel)));
/*
* Create the ForeignScan node for the given relation.
@@ -1657,9 +1703,15 @@ postgresGetForeignPlan(PlannerInfo *root,
/*
* Construct a tuple descriptor for the scan tuples handled by a foreign join.
+ *
+ * 'rtfuncdata' is the FdwScanPrivateFunctions list saved at plan time, and
+ * 'rtoffset' is the difference between the executor's RT indexes and the
+ * scan-local RT indexes captured in that list. Both may be 0/NIL when the
+ * scan has no RTE_FUNCTION dependents.
*/
static TupleDesc
-get_tupdesc_for_join_scan_tuples(ForeignScanState *node)
+get_tupdesc_for_join_scan_tuples(ForeignScanState *node,
+ List *rtfuncdata, int rtoffset)
{
ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
EState *estate = node->ss.ps.state;
@@ -1695,13 +1747,62 @@ get_tupdesc_for_join_scan_tuples(ForeignScanState *node)
if (!IsA(var, Var) || var->varattno != 0)
continue;
rte = list_nth(estate->es_range_table, var->varno - 1);
- if (rte->rtekind != RTE_RELATION)
- continue;
- reltype = get_rel_type_id(rte->relid);
- if (!OidIsValid(reltype))
- continue;
- att->atttypid = reltype;
- /* shouldn't need to change anything else */
+
+ if (rte->rtekind == RTE_RELATION)
+ {
+ reltype = get_rel_type_id(rte->relid);
+ if (!OidIsValid(reltype))
+ continue;
+ att->atttypid = reltype;
+ /* shouldn't need to change anything else */
+ }
+ else if (rte->rtekind == RTE_FUNCTION && rtfuncdata != NIL)
+ {
+ /*
+ * A whole-row Var points at a FUNCTION RTE absorbed into the
+ * foreign join. Synthesize an anonymous composite TupleDesc from
+ * the per-function return-type metadata we saved at plan time;
+ * the deparser emits these as ROW(f<rti>.c1, f<rti>.c2, ...).
+ */
+ List *funcdata;
+ TupleDesc rte_tupdesc;
+ int num_funcs;
+ int attnum;
+ ListCell *lc1,
+ *lc2;
+
+ funcdata = list_nth(rtfuncdata, var->varno - rtoffset);
+ if (funcdata == NIL)
+ continue;
+ num_funcs = list_length(funcdata);
+ Assert(num_funcs == list_length(rte->eref->colnames));
+ rte_tupdesc = CreateTemplateTupleDesc(num_funcs);
+
+ attnum = 1;
+ forboth(lc1, funcdata, lc2, rte->eref->colnames)
+ {
+ List *fdata = lfirst_node(List, lc1);
+ char *colname = strVal(lfirst(lc2));
+ Oid funcrettype;
+ Oid funccollation;
+
+ funcrettype = lsecond_node(Integer, fdata)->ival;
+ funccollation = lthird_node(Integer, fdata)->ival;
+
+ if (!OidIsValid(funcrettype) || funcrettype == RECORDOID)
+ elog(ERROR,
+ "could not determine return type for function in foreign scan");
+
+ TupleDescInitEntry(rte_tupdesc, (AttrNumber) attnum, colname,
+ funcrettype, -1, 0);
+ TupleDescInitEntryCollation(rte_tupdesc, (AttrNumber) attnum,
+ funccollation);
+ attnum++;
+ }
+
+ assign_record_type_typmod(rte_tupdesc);
+ att->atttypmod = rte_tupdesc->tdtypmod;
+ }
}
return tupdesc;
}
@@ -1737,14 +1838,30 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
/*
* Identify which user to do the remote access as. This should match what
- * ExecCheckPermissions() does.
+ * ExecCheckPermissions() does. For a join, scan the base relids until we
+ * find an RTE_RELATION (the foreign-table side); ignore any RTE_FUNCTION
+ * absorbed into the join, which contributes no relation OID to look up.
*/
userid = OidIsValid(fsplan->checkAsUser) ? fsplan->checkAsUser : GetUserId();
+ rte = NULL;
if (fsplan->scan.scanrelid > 0)
+ {
rtindex = fsplan->scan.scanrelid;
+ rte = exec_rt_fetch(rtindex, estate);
+ }
else
- rtindex = bms_next_member(fsplan->fs_base_relids, -1);
- rte = exec_rt_fetch(rtindex, estate);
+ {
+ rtindex = -1;
+ while ((rtindex = bms_next_member(fsplan->fs_base_relids, rtindex)) >= 0)
+ {
+ rte = exec_rt_fetch(rtindex, estate);
+ if (rte != NULL && rte->rtekind == RTE_RELATION)
+ break;
+ rte = NULL;
+ }
+ if (rte == NULL)
+ elog(ERROR, "could not locate a foreign relation RTE in foreign scan");
+ }
/* Get info about foreign table. */
table = GetForeignTable(rte->relid);
@@ -1787,8 +1904,19 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
}
else
{
+ List *rtfuncdata = (List *) list_nth(fsplan->fdw_private,
+ FdwScanPrivateFunctions);
+ int min_base_rti = intVal(list_nth(fsplan->fdw_private,
+ FdwScanPrivateMinRTIndex));
+ int rtoffset = bms_next_member(fsplan->fs_base_relids, -1) -
+ min_base_rti;
+
+ Assert(min_base_rti > 0);
+ Assert(rtoffset >= 0);
+
fsstate->rel = NULL;
- fsstate->tupdesc = get_tupdesc_for_join_scan_tuples(node);
+ fsstate->tupdesc = get_tupdesc_for_join_scan_tuples(node, rtfuncdata,
+ rtoffset);
}
fsstate->attinmeta = TupleDescGetAttInMetadata(fsstate->tupdesc);
@@ -2828,6 +2956,10 @@ postgresPlanDirectModify(PlannerInfo *root,
makeBoolean((retrieved_attrs != NIL)),
retrieved_attrs,
makeBoolean(plan->canSetTag));
+ fscan->fdw_private = lappend(fscan->fdw_private,
+ get_functions_data(root, foreignrel));
+ fscan->fdw_private = lappend(fscan->fdw_private,
+ makeInteger(get_min_base_rti(root, foreignrel)));
/*
* Update the foreign-join-related fields.
@@ -2941,7 +3073,26 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags)
TupleDesc tupdesc;
if (fsplan->scan.scanrelid == 0)
- tupdesc = get_tupdesc_for_join_scan_tuples(node);
+ {
+ /*
+ * DirectModify on a foreign join: use the per-RTE function
+ * metadata saved at plan time so a whole-row Var pointing at a
+ * function RTE absorbed into the join can be rebuilt into a
+ * usable TupleDesc (e.g. RETURNING t for a join with UNNEST(...,
+ * ...) AS t(bx, i)).
+ */
+ List *rtfuncdata = (List *) list_nth(fsplan->fdw_private,
+ FdwDirectModifyPrivateFunctions);
+ int min_base_rti = intVal(list_nth(fsplan->fdw_private,
+ FdwDirectModifyPrivateMinRTIndex));
+ int rtoffset = bms_next_member(fsplan->fs_base_relids, -1) -
+ min_base_rti;
+
+ Assert(min_base_rti > 0);
+ Assert(rtoffset >= 0);
+
+ tupdesc = get_tupdesc_for_join_scan_tuples(node, rtfuncdata, rtoffset);
+ }
else
tupdesc = RelationGetDescr(dmstate->rel);
@@ -3054,7 +3205,8 @@ postgresExplainForeignScan(ForeignScanState *node, ExplainState *es)
* We do that here, not when the plan is created, because we can't know
* what aliases ruleutils.c will assign at plan creation time.
*/
- if (list_length(fdw_private) > FdwScanPrivateRelations)
+ if (list_length(fdw_private) > FdwScanPrivateRelations &&
+ list_nth(fdw_private, FdwScanPrivateRelations) != NULL)
{
StringInfoData relations;
char *rawrelations;
@@ -3104,6 +3256,22 @@ postgresExplainForeignScan(ForeignScanState *node, ExplainState *es)
rti += rtoffset;
Assert(bms_is_member(rti, plan->fs_base_relids));
rte = rt_fetch(rti, es->rtable);
+
+ /*
+ * If a function RTE was absorbed into the foreign join,
+ * render it as "Function <alias>" since we have no foreign
+ * relid.
+ */
+ if (rte->rtekind == RTE_FUNCTION)
+ {
+ refname = (char *) list_nth(es->rtable_names, rti - 1);
+ if (refname == NULL)
+ refname = rte->eref->aliasname;
+ appendStringInfo(&relations, "Function %s",
+ quote_identifier(refname));
+ continue;
+ }
+
Assert(rte->rtekind == RTE_RELATION);
/* This logic should agree with explain.c's ExplainTargetRel */
relname = get_rel_name(rte->relid);
@@ -3479,8 +3647,17 @@ estimate_path_cost_size(PlannerInfo *root,
/* For join we expect inner and outer relations set */
Assert(fpinfo->innerrel && fpinfo->outerrel);
- fpinfo_i = (PgFdwRelationInfo *) fpinfo->innerrel->fdw_private;
- fpinfo_o = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
+ /*
+ * For a FUNCTION RTE absorbed into the join, use the stub fpinfo
+ * we built in foreign_join_ok(), since the function rel itself
+ * has no fdw_private.
+ */
+ fpinfo_i = fpinfo->inner_func_fpinfo ?
+ fpinfo->inner_func_fpinfo :
+ (PgFdwRelationInfo *) fpinfo->innerrel->fdw_private;
+ fpinfo_o = fpinfo->outer_func_fpinfo ?
+ fpinfo->outer_func_fpinfo :
+ (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
/* Estimate of number of rows in cross product */
nrows = fpinfo_i->rows * fpinfo_o->rows;
@@ -6619,6 +6796,181 @@ semijoin_target_ok(PlannerInfo *root, RelOptInfo *joinrel, RelOptInfo *outerrel,
return ok;
}
+/*
+ * get_base_relids
+ * Return the set of base relids referenced by a foreign scan rel.
+ *
+ * For an upper rel we use the all-query relids minus the outer joins;
+ * otherwise the rel's own relids minus the outer joins. The result matches
+ * the relids that create_foreignscan_plan() ultimately uses for
+ * ForeignScan.fs_base_relids, so it is suitable for any tagging we want to
+ * store via plan-private state.
+ */
+static Relids
+get_base_relids(PlannerInfo *root, RelOptInfo *rel)
+{
+ Relids relids;
+
+ if (rel->reloptkind == RELOPT_UPPER_REL)
+ relids = root->all_query_rels;
+ else
+ relids = rel->relids;
+
+ return bms_difference(relids, root->outer_join_rels);
+}
+
+/*
+ * get_min_base_rti
+ * Lowest base RT index in the foreign scan rel.
+ *
+ * After setrefs.c flattens the rtable, the scan-local indexes saved in
+ * plan-private data can be translated to estate indexes by adding
+ * (ForeignScan.fs_base_relids min - this value). Captured at plan time
+ * because create_foreignscan_plan() computes the same value internally.
+ */
+static int
+get_min_base_rti(PlannerInfo *root, RelOptInfo *rel)
+{
+ Relids relids = get_base_relids(root, rel);
+
+ return bms_next_member(relids, -1);
+}
+
+/*
+ * get_functions_data
+ * Build the per-RTE function metadata list saved as
+ * FdwScanPrivateFunctions.
+ *
+ * The result list is indexed by base RT index relative to the lowest base
+ * RT index of the scan. Each element is either NULL (for non-RTE_FUNCTION
+ * base rels in this scan) or a List of List of three Integer nodes:
+ * (funcid, funcrettype, funccollation) -- one inner list per RangeTblFunction.
+ *
+ * Only RTE_FUNCTION relids actually appearing in the foreign scan's
+ * fs_base_relids contribute; others are placeholders so that the consumer
+ * can index into the result by RTI offset.
+ */
+static List *
+get_functions_data(PlannerInfo *root, RelOptInfo *rel)
+{
+ List *rtfuncdata = NIL;
+ Relids fscan_relids = get_base_relids(root, rel);
+ int i;
+
+ for (i = 0; i < root->simple_rel_array_size; i++)
+ {
+ RangeTblEntry *rte = root->simple_rte_array[i];
+ List *funcdata = NIL;
+ ListCell *lc;
+
+ if (rte == NULL || i == 0 ||
+ !bms_is_member(i, fscan_relids) ||
+ rte->rtekind != RTE_FUNCTION)
+ {
+ rtfuncdata = lappend(rtfuncdata, NULL);
+ continue;
+ }
+
+ foreach(lc, rte->functions)
+ {
+ RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
+ Oid funcrettype;
+ Oid funccollation;
+ TupleDesc tupdesc;
+ Oid funcid = InvalidOid;
+
+ get_expr_result_type(rtfunc->funcexpr, &funcrettype, &tupdesc);
+
+ if (!OidIsValid(funcrettype) || funcrettype == RECORDOID)
+ elog(ERROR,
+ "could not determine return type for function in foreign scan");
+
+ funccollation = exprCollation(rtfunc->funcexpr);
+
+ if (IsA(rtfunc->funcexpr, FuncExpr))
+ funcid = ((FuncExpr *) rtfunc->funcexpr)->funcid;
+
+ funcdata = lappend(funcdata,
+ list_make3(makeInteger(funcid),
+ makeInteger(funcrettype),
+ makeInteger(funccollation)));
+ }
+
+ rtfuncdata = lappend(rtfuncdata, funcdata);
+ }
+
+ return rtfuncdata;
+}
+
+/*
+ * Check if a relation is a FUNCTION RTE that can be absorbed into a remote
+ * join. Every function in the RTE must
+ *
+ * - return a well-defined scalar type -- we don't ship records/composite
+ * since the remote server cannot reconstruct a column definition list
+ * and our deparser does not emit one;
+ * - have a shippable expression with no mutable subnodes -- is_foreign_expr()
+ * rejects volatile/stable functions through contain_mutable_functions(),
+ * so the IMMUTABLE-only restriction is implicit;
+ * - not contain SubPlans -- we'd otherwise need to ship sub-results to
+ * the remote, which we do not implement.
+ *
+ * WITH ORDINALITY is not supported yet.
+ */
+static bool
+function_rte_pushdown_ok(PlannerInfo *root, RelOptInfo *rel,
+ RelOptInfo *fdwrel)
+{
+ RangeTblEntry *rte;
+ ListCell *lc;
+
+ if (rel->rtekind != RTE_FUNCTION)
+ return false;
+ rte = planner_rt_fetch(rel->relid, root);
+ if (rte->rtekind != RTE_FUNCTION)
+ return false;
+ if (rte->funcordinality)
+ return false;
+
+ /*
+ * Reject up-front any function RTE that lateral-references another
+ * relation: foreign-join push-down would need to parameterise the remote
+ * query per outer row, which we don't support, and even considering the
+ * path is expensive on the planner side. The surrounding lateral_relids
+ * check in postgresGetForeignJoinPaths() would normally bail out for the
+ * joinrel, but doing the check here avoids walking the function
+ * expression entirely.
+ */
+ if (!bms_is_empty(rel->lateral_relids))
+ return false;
+
+ Assert(list_length(rte->functions) >= 1);
+
+ foreach(lc, rte->functions)
+ {
+ RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
+ TypeFuncClass functypclass;
+ Oid funcrettype;
+ TupleDesc tupdesc;
+
+ functypclass = get_expr_result_type(rtfunc->funcexpr,
+ &funcrettype, &tupdesc);
+ if (functypclass != TYPEFUNC_SCALAR)
+ return false;
+ if (!OidIsValid(funcrettype) ||
+ funcrettype == RECORDOID ||
+ funcrettype == VOIDOID)
+ return false;
+
+ if (contain_subplans(rtfunc->funcexpr))
+ return false;
+ if (!is_foreign_expr(root, fdwrel, (Expr *) rtfunc->funcexpr))
+ return false;
+ }
+
+ return true;
+}
+
/*
* Assess whether the join between inner and outer relations can be pushed down
* to the foreign server. As a side effect, save information we obtain in this
@@ -6634,6 +6986,8 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
PgFdwRelationInfo *fpinfo_i;
ListCell *lc;
List *joinclauses;
+ bool outer_is_function = false;
+ bool inner_is_function = false;
/*
* We support pushing down INNER, LEFT, RIGHT, FULL OUTER and SEMI joins.
@@ -6652,15 +7006,70 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
return false;
/*
- * If either of the joining relations is marked as unsafe to pushdown, the
- * join can not be pushed down.
+ * Detect mixed (foreign x function-RTE) cases. Only INNER joins are
+ * supported initially. We dispatch on rtekind here so that the same
+ * function RTE can be absorbed into joins on multiple foreign servers
+ * (each call gets its own stub fpinfo and rechecks shippability for the
+ * specific server).
*/
fpinfo = (PgFdwRelationInfo *) joinrel->fdw_private;
- fpinfo_o = (PgFdwRelationInfo *) outerrel->fdw_private;
- fpinfo_i = (PgFdwRelationInfo *) innerrel->fdw_private;
- if (!fpinfo_o || !fpinfo_o->pushdown_safe ||
- !fpinfo_i || !fpinfo_i->pushdown_safe)
- return false;
+ if (jointype == JOIN_INNER && innerrel->rtekind == RTE_FUNCTION &&
+ (fpinfo_o = (PgFdwRelationInfo *) outerrel->fdw_private) &&
+ fpinfo_o->pushdown_safe &&
+ function_rte_pushdown_ok(root, innerrel, outerrel))
+ {
+ inner_is_function = true;
+ }
+ else if (jointype == JOIN_INNER && outerrel->rtekind == RTE_FUNCTION &&
+ (fpinfo_i = (PgFdwRelationInfo *) innerrel->fdw_private) &&
+ fpinfo_i->pushdown_safe &&
+ function_rte_pushdown_ok(root, outerrel, innerrel))
+ {
+ outer_is_function = true;
+ }
+ else
+ {
+ fpinfo_o = (PgFdwRelationInfo *) outerrel->fdw_private;
+ fpinfo_i = (PgFdwRelationInfo *) innerrel->fdw_private;
+ if (!fpinfo_o || !fpinfo_o->pushdown_safe ||
+ !fpinfo_i || !fpinfo_i->pushdown_safe)
+ return false;
+ }
+
+ /*
+ * If one side is a function RTE, allocate a stub fpinfo so the rest of
+ * this function and the cost estimator can treat it uniformly. We hand
+ * the stub to the joinrel's deparser via the same path the foreign side
+ * uses, but we never permanently attach it to the function rel's
+ * fdw_private (different joinrels may pair the same function RTE with
+ * different foreign servers).
+ */
+ if (inner_is_function)
+ {
+ fpinfo_i = palloc0_object(PgFdwRelationInfo);
+ fpinfo_i->pushdown_safe = true;
+ fpinfo_i->server = fpinfo_o->server;
+ fpinfo_i->relation_name = psprintf("%u", innerrel->relid);
+ fpinfo_i->rows = innerrel->rows;
+ fpinfo_i->width = innerrel->reltarget->width;
+ fpinfo_i->retrieved_rows = innerrel->rows;
+ fpinfo_i->rel_startup_cost = 0;
+ fpinfo_i->rel_total_cost = 0;
+ fpinfo->inner_func_fpinfo = fpinfo_i;
+ }
+ else if (outer_is_function)
+ {
+ fpinfo_o = palloc0_object(PgFdwRelationInfo);
+ fpinfo_o->pushdown_safe = true;
+ fpinfo_o->server = fpinfo_i->server;
+ fpinfo_o->relation_name = psprintf("%u", outerrel->relid);
+ fpinfo_o->rows = outerrel->rows;
+ fpinfo_o->width = outerrel->reltarget->width;
+ fpinfo_o->retrieved_rows = outerrel->rows;
+ fpinfo_o->rel_startup_cost = 0;
+ fpinfo_o->rel_total_cost = 0;
+ fpinfo->outer_func_fpinfo = fpinfo_o;
+ }
/*
* If joining relations have local conditions, those conditions are
diff --git a/contrib/postgres_fdw/postgres_fdw.h b/contrib/postgres_fdw/postgres_fdw.h
index a2bb1ff352c..5b2ffcf06f7 100644
--- a/contrib/postgres_fdw/postgres_fdw.h
+++ b/contrib/postgres_fdw/postgres_fdw.h
@@ -106,6 +106,16 @@ typedef struct PgFdwRelationInfo
/* joinclauses contains only JOIN/ON conditions for an outer join */
List *joinclauses; /* List of RestrictInfo */
+ /*
+ * If a FUNCTION RTE was absorbed into this join, these point at the stub
+ * PgFdwRelationInfo for the function side (paired with the
+ * outerrel/innerrel), so the cost estimator and deparser can find it
+ * without consulting the function rel's fdw_private. At most one of
+ * outer_func_fpinfo/inner_func_fpinfo is set.
+ */
+ struct PgFdwRelationInfo *outer_func_fpinfo;
+ struct PgFdwRelationInfo *inner_func_fpinfo;
+
/* Upper relation information */
UpperRelationKind stage;
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 267d3c1a7e7..f49fbc9317e 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -790,6 +790,189 @@ SELECT t1.c1, t2.c2 FROM v4 t1 LEFT JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c
SELECT t1.c1, t2.c2 FROM v4 t1 LEFT JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1 OFFSET 10 LIMIT 10;
ALTER VIEW v4 OWNER TO regress_view_owner;
+-- ===================================================================
+-- Foreign-join with FUNCTION RTE pushdown (IMMUTABLE functions only)
+-- ===================================================================
+-- IMMUTABLE function: unnest of constant array can be pushed down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t1.c3 FROM ft1 t1, unnest(ARRAY[1, 5, 10, 100]::int[]) AS u(id)
+WHERE t1.c1 = u.id ORDER BY t1.c1;
+SELECT t1.c1, t1.c3 FROM ft1 t1, unnest(ARRAY[1, 5, 10, 100]::int[]) AS u(id)
+WHERE t1.c1 = u.id ORDER BY t1.c1;
+
+-- IMMUTABLE function: generate_series with constant args
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1 FROM ft1 t1, generate_series(1, 4) AS g(id)
+WHERE t1.c1 = g.id ORDER BY t1.c1;
+SELECT t1.c1 FROM ft1 t1, generate_series(1, 4) AS g(id)
+WHERE t1.c1 = g.id ORDER BY t1.c1;
+
+-- VOLATILE function (random) must NOT be pushed down
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1 FROM ft1 t1, generate_series(1, 4 + (random() * 0)::int) AS g(id)
+WHERE t1.c1 = g.id;
+
+-- WITH ORDINALITY must NOT be pushed down (limitation of this implementation)
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, u.ord
+FROM ft1 t1, unnest(ARRAY[1, 5, 10]::int[]) WITH ORDINALITY AS u(id, ord)
+WHERE t1.c1 = u.id;
+
+-- Same function RTE joined with two different foreign servers: planner picks
+-- one absorption + a local join with the second foreign server. The fact
+-- that the function is IMMUTABLE makes this safe even if both sides chose to
+-- absorb it independently.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1
+FROM ft1 t1, ft6 t2, unnest(ARRAY[1, 5, 10, 100]::int[]) AS u(id)
+WHERE t1.c1 = u.id AND t2.c1 = u.id ORDER BY t1.c1;
+
+-- Cost-based selection between two foreign servers: ft1 ("S 1"."T 1") has
+-- 1000 rows, ft6 ("S 1"."T 4") has ~33 rows. The same query shape gets a
+-- different push-down target depending on a predicate that changes the
+-- effective cardinality of one side -- the function "jumps" to whichever
+-- foreign scan benefits more from being pre-filtered.
+ANALYZE ft1;
+ANALYZE ft6;
+-- No extra predicate: ft1 is the bigger side, function absorbed there.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1
+FROM ft1 t1, ft6 t2, unnest(ARRAY[3, 6, 9, 12, 15, 18]::int[]) AS u(id)
+WHERE t1.c1 = u.id AND t2.c1 = u.id;
+-- Selective predicate on ft1.c3 (not in the eqclass) shrinks ft1 to a
+-- handful of remote rows; now ft6 is effectively the bigger side and the
+-- function is absorbed into ft6 instead.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1
+FROM ft1 t1, ft6 t2, unnest(ARRAY[3, 6, 9, 12, 15, 18]::int[]) AS u(id)
+WHERE t1.c1 = u.id AND t2.c1 = u.id AND t1.c3 < '00010';
+
+-- The remaining scenarios reuse a dedicated foreign table to cover the
+-- corner cases of FUNCTION RTE push-down: function-first FROM, record
+-- return type rejection, whole-row reference, UPDATE...FROM..., and
+-- multi-function ROWS FROM.
+CREATE TABLE base_tbl_fn (a int, b int);
+INSERT INTO base_tbl_fn
+ SELECT g, g + 100 FROM generate_series(1, 30) g;
+CREATE FOREIGN TABLE remote_tbl (a int, b int)
+ SERVER loopback OPTIONS (table_name 'base_tbl_fn');
+
+-- The function RTE appears first in FROM; the foreign relation must be
+-- found by scanning fs_base_relids for an RTE_RELATION rather than
+-- using scan->fs_relid blindly.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n;
+SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
+WHERE r.a = n ORDER BY r.a;
+
+-- A function returning record (composite) is forbidden; pushing it
+-- would yield a remote "column definition list is required" error.
+-- function_rte_pushdown_ok() rejects it via TYPEFUNC_SCALAR.
+CREATE OR REPLACE FUNCTION f_ret_record() RETURNS record AS $$
+ SELECT (1, 2)::record
+$$ LANGUAGE SQL IMMUTABLE;
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT s FROM remote_tbl rt, f_ret_record() AS s(a int, b int)
+WHERE s.a = rt.a;
+DROP FUNCTION f_ret_record();
+
+-- UPDATE ... FROM unnest() with a complex element type; area(box)
+-- yields the value to match. The locking machinery for the
+-- non-relation RTE generates a whole-row Var that deparseColumnRef
+-- emits as ROW(f<rti>.c1, ...).
+UPDATE remote_tbl r SET b = 999
+FROM unnest(array[box '((2,3),(-2,-3))']) AS t(bx)
+WHERE r.a = area(t.bx);
+SELECT * FROM remote_tbl WHERE a IN (23, 24, 25) ORDER BY a;
+
+-- The same shape with CASE and RETURNING; exercises the DirectModify
+-- path and the executor's tuple-desc reconstruction.
+UPDATE remote_tbl r
+ SET b = CASE WHEN random() >= 0 THEN 5 ELSE 0 END
+ FROM unnest(array[box '((2,3),(-2,-3))']) AS t(bx)
+ WHERE r.a = area(t.bx) RETURNING a, b;
+
+-- RETURNING a whole-row reference to the function RTE. Without the
+-- per-RTE function metadata being preserved on the DirectModify path
+-- (FdwDirectModifyPrivateFunctions / FdwDirectModifyPrivateMinRTIndex),
+-- this would fail with "input of anonymous composite types is not
+-- implemented".
+UPDATE remote_tbl r SET b = 7
+ FROM unnest(array[box '((2,3),(-2,-3))'],
+ array[int '1']) AS t(bx, i)
+ WHERE r.a = area(t.bx) RETURNING a, b, t;
+
+-- ROWS FROM (...) with several functions. Force pushdown because the
+-- cost model otherwise picks a local plan.
+SET enable_hashjoin = off;
+SET enable_mergejoin = off;
+SET enable_nestloop = off;
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a, t.n, t.s
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+SELECT r.a, t.n, t.s
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+
+-- Whole-row Var on the absorbed function side (e.g. via a cast to
+-- text). Exercises both deparseColumnRef whole-row branch and the
+-- get_tupdesc_for_join_scan_tuples() RTE_FUNCTION metadata path.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t::text, r.a
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+SELECT t::text, r.a
+ FROM remote_tbl r, ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(11, 13)) AS t(n, s)
+ WHERE r.a = t.n ORDER BY r.a;
+
+-- Check whole-row Var represented by function on the nullable
+-- left join side
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT u, ft5.c1, ft5.c2, ft4.c1, ft4.c2 FROM ft5 LEFT JOIN
+(ft4 JOIN unnest(array[1,2], array[3,4]) as u (u1, u2) ON ft4.c1=u1)
+ON ft5.c1 = ft4.c1 WHERE ft5.c1 < 10 ORDER BY ft5.c1;
+SELECT u, ft5.c1, ft5.c2, ft4.c1, ft4.c2 FROM ft5 LEFT JOIN
+(ft4 JOIN unnest(array[1,2], array[3,4]) as u (u1, u2) ON ft4.c1=u1)
+ON ft5.c1 = ft4.c1 WHERE ft5.c1 < 10 ORDER BY ft5.c1;
+RESET enable_hashjoin;
+RESET enable_mergejoin;
+RESET enable_nestloop;
+
+-- Volatile function in ROWS FROM disqualifies the whole RTE.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a FROM remote_tbl r,
+ ROWS FROM (unnest(array[3, 6, 9]),
+ generate_series(1, 4 + (random() * 0)::int)) AS t(n, s)
+ WHERE r.a = t.n;
+
+-- LATERAL function referencing a foreign Var: postgres_fdw's
+-- foreign-join pushdown rejects this via the joinrel->lateral_relids
+-- check; the plan is therefore a local NestLoop + FunctionScan.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a, t.x FROM remote_tbl r, LATERAL unnest(array[r.a]) AS t(x)
+WHERE r.a <= 3 ORDER BY r.a;
+
+-- Outer joins with the function RTE are not pushed down (only INNER
+-- joins are supported by function_rte_pushdown_ok()).
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a, t.n FROM remote_tbl r
+ LEFT JOIN unnest(array[1, 2, 3]) AS t(n) ON r.a = t.n
+ WHERE r.a <= 5 ORDER BY r.a;
+
+-- SEMI join (EXISTS) with a function RTE is also not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT r.a FROM remote_tbl r
+ WHERE EXISTS (SELECT 1 FROM unnest(array[3, 6, 9]) AS t(n) WHERE t.n = r.a)
+ ORDER BY r.a;
+
+DROP FOREIGN TABLE remote_tbl;
+DROP TABLE base_tbl_fn;
+
-- ====================================================================
-- Check that userid to use when querying the remote table is correctly
-- propagated into foreign rels present in subqueries under an UNION ALL
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 3fc2c2f71d0..f21ae1baeb2 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -746,6 +746,30 @@ set_foreign_rel_properties(RelOptInfo *joinrel, RelOptInfo *outer_rel,
joinrel->fdwroutine = outer_rel->fdwroutine;
}
}
+ else if (OidIsValid(outer_rel->serverid) &&
+ inner_rel->rtekind == RTE_FUNCTION)
+ {
+ /*
+ * One side is a foreign relation, the other side is a function RTE.
+ * If the function is IMMUTABLE, the FDW can absorb the function call
+ * into the remote query (the result is identical regardless of which
+ * server evaluates it). Let the FDW decide whether the join is
+ * actually shippable; here we just propagate the FDW routine so the
+ * FDW gets a chance.
+ */
+ joinrel->serverid = outer_rel->serverid;
+ joinrel->userid = outer_rel->userid;
+ joinrel->useridiscurrent = outer_rel->useridiscurrent;
+ joinrel->fdwroutine = outer_rel->fdwroutine;
+ }
+ else if (OidIsValid(inner_rel->serverid) &&
+ outer_rel->rtekind == RTE_FUNCTION)
+ {
+ joinrel->serverid = inner_rel->serverid;
+ joinrel->userid = inner_rel->userid;
+ joinrel->useridiscurrent = inner_rel->useridiscurrent;
+ joinrel->fdwroutine = inner_rel->fdwroutine;
+ }
}
/*
--
2.43.0
