database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2026-10-23 13:29:09 +03:00
Code Activity

postgres_fdw: push down FUNCTION RTE into foreign joins

Browse Source 
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.

Discussion: https://postgr.es/m/e3af56f9b2f1bd9fdf12aff6ca25b18d%40postgrespro.ru
Author: Alexander Pyhalov <a.pyhalov@postgrespro.ru>
Reviewed-by: Solaimurugan Vellaipandiyan <drsolaimurugan.v@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
This commit is contained in:
Alexander Korotkov
2026-08-19 13:29:47 +03:00
parent e13851080c
commit 0ee83dd4a9
7 changed files with 1698 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files

157
contrib/postgres_fdw/deparse.c
View File

@@ -68,6 +68,7 @@ typedef struct foreign_glob_cxt
{
PlannerInfo *root; /* global planner state */
RelOptInfo *foreignrel; /* the foreign relation we are planning for */
PgFdwRelationInfo *fpinfo; /* the foreign server info we should rely on */
Relids relids; /* relids of base relations in the underlying
* scan */
} foreign_glob_cxt;
@@ -112,6 +113,7 @@ 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
@@ -217,6 +219,7 @@ static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
void
classifyConditions(PlannerInfo *root,
RelOptInfo *baserel,
PgFdwRelationInfo *fpinfo,
List *input_conds,
List **remote_conds,
List **local_conds)
@@ -230,7 +233,7 @@ classifyConditions(PlannerInfo *root,
{
RestrictInfo *ri = lfirst_node(RestrictInfo, lc);
if (is_foreign_expr(root, baserel, ri->clause))
if (is_foreign_expr(root, baserel, fpinfo, ri->clause))
*remote_conds = lappend(*remote_conds, ri);
else
*local_conds = lappend(*local_conds, ri);
@@ -243,11 +246,11 @@ classifyConditions(PlannerInfo *root,
bool
is_foreign_expr(PlannerInfo *root,
RelOptInfo *baserel,
PgFdwRelationInfo *fpinfo,
Expr *expr)
{
foreign_glob_cxt glob_cxt;
foreign_loc_cxt loc_cxt;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
/*
* Check that the expression consists of nodes that are safe to execute
@@ -255,6 +258,7 @@ is_foreign_expr(PlannerInfo *root,
*/
glob_cxt.root = root;
glob_cxt.foreignrel = baserel;
glob_cxt.fpinfo = fpinfo;
/*
* For an upper relation, use relids from its underneath scan relation,
@@ -324,8 +328,8 @@ foreign_expr_walker(Node *node,
if (node == NULL)
return true;
/* May need server info from baserel's fdw_private struct */
fpinfo = (PgFdwRelationInfo *) (glob_cxt->foreignrel->fdw_private);
/* May need server info from global context */
fpinfo = glob_cxt->fpinfo;
/* Set up inner_cxt for possible recursion to child nodes */
inner_cxt.collation = InvalidOid;
@@ -2050,6 +2054,72 @@ 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
@@ -2060,7 +2130,22 @@ 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));
@@ -2732,6 +2817,68 @@ 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;
/*
* The CASE WHEN wrapper distinguishes a NULL-supplied outer-join
* row (whole-row Var is NULL) from a row whose columns all happen
* to be NULL (whole-row Var is ROW(NULL, ..., NULL)). A bare
* ROW(...) would collapse those two cases to the latter.
*
* Both cases arise already. Only INNER joins with a function RTE
* are absorbed, but the resulting join may itself end up on the
* nullable side of an outer join that we push down as well, and
* then the remote query supplies NULLs for the whole function
* side. Without the wrapper such a row would come back as
* ROW(NULL, ..., NULL), that is, as if the function had returned
* a row of NULLs rather than no row at all.
*/
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)
{

627
contrib/postgres_fdw/expected/postgres_fdw.out
View File

@@ -2960,6 +2960,633 @@ 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 (pg_catalog.unnest() 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 (pg_catalog.generate_series() 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)
-- STABLE function must NOT be pushed down either: even though its result is
-- constant within one query, evaluating it on the remote server could yield
-- a different value than evaluating it locally.
CREATE FUNCTION f_stable(int) RETURNS SETOF int LANGUAGE plpgsql STABLE AS
$$ BEGIN RETURN QUERY SELECT generate_series(1, $1); END $$;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1 FROM ft1 t1, f_stable(4) AS g(id) WHERE t1.c1 = g.id;
QUERY PLAN
---------------------------------------------------------
Hash Join
Output: t1.c1
Hash Cond: (g.id = t1.c1)
-> Function Scan on public.f_stable g
Output: g.id
Function Call: f_stable(4)
-> 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)
DROP FUNCTION f_stable(int);
-- 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 (pg_catalog.unnest() 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 (pg_catalog.unnest() 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 (pg_catalog.unnest() 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: (pg_catalog.unnest() 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)
-- Function RTE is restricted, shippable conditions
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n and n > 3;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: n.n, r.a, r.b
Relations: (pg_catalog.unnest() 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)) AND ((f1.c1 > 3))))
(4 rows)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
WHERE r.a = n and n > 3 ORDER BY r.a;
n | a | b
---+---+-----
4 | 4 | 104
(1 row)
-- Function RTE is restricted, nonshippable conditions
CREATE FUNCTION f_local(int) RETURNS int AS $$
BEGIN
RETURN $1;
END
$$ LANGUAGE plpgsql;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n and n > f_local(3);
QUERY PLAN
-----------------------------------------------------------
Hash Join
Output: n.n, r.a, r.b
Hash Cond: (r.a = n.n)
-> Foreign Scan on public.remote_tbl r
Output: r.a, r.b
Remote SQL: SELECT a, b FROM public.base_tbl_fn
-> Hash
Output: n.n
-> Function Scan on pg_catalog.unnest n
Output: n.n
Function Call: unnest('{2,3,4}'::integer[])
Filter: (n.n > f_local(3))
(12 rows)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
WHERE r.a = n and n > f_local(3) ORDER BY r.a;
n | a | b
---+---+-----
4 | 4 | 104
(1 row)
DROP FUNCTION f_local(int);
-- Check that a qual on the function RTE using a function from a shippable
-- extension is pushed down. plpgsql (not inlined) with the column as
-- argument (not const-folded) keeps the function call in the qual.
CREATE FUNCTION f_ext(int) RETURNS int AS $$
BEGIN RETURN $1; END
$$ LANGUAGE plpgsql IMMUTABLE;
ALTER EXTENSION postgres_fdw ADD FUNCTION f_ext(int);
-- Force pushdown so the fixed-code plan is deterministically a Foreign
-- Scan; on the unfixed code the qual is classified local, the join is
-- refused, and the plan falls back to a local join instead.
SET enable_hashjoin = off;
SET enable_mergejoin = off;
SET enable_nestloop = off;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n and f_ext(n) > 3;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: n.n, r.a, r.b
Relations: (pg_catalog.unnest() 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)) AND ((public.f_ext(f1.c1) > 3))))
(4 rows)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
WHERE r.a = n and f_ext(n) > 3 ORDER BY r.a;
n | a | b
---+---+-----
4 | 4 | 104
(1 row)
RESET enable_hashjoin;
RESET enable_mergejoin;
RESET enable_nestloop;
ALTER EXTENSION postgres_fdw DROP FUNCTION f_ext(int);
DROP FUNCTION f_ext(int);
-- 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 (ROWS FROM (pg_catalog.unnest(), pg_catalog.generate_series()) 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 (ROWS FROM (pg_catalog.unnest(), pg_catalog.generate_series()) 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 (ROWS FROM (pg_catalog.unnest(), pg_catalog.unnest()) 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)
-- Same nullable-side whole-row Var, but with outer rows that both match
-- and miss the (foreign x function) inner join. A multi-column function
-- RTE is used so that the reference is a genuine whole-row Var (a single
-- scalar-returning function would collapse to its lone column). This
-- exercises the THEN ROW(...) side of deparseColumnRef()'s whole-row CASE
-- (matched rows reconstruct the composite) as well as the NULL side
-- (missed rows), confirming the executor rebuilds the anonymous composite
-- correctly.
EXPLAIN (VERBOSE, COSTS OFF)
SELECT l.a, t FROM remote_tbl l
LEFT JOIN (remote_tbl r JOIN unnest(array[2, 4], array[20, 40]) AS t(x, y)
ON r.a = t.x)
ON l.a = r.a
WHERE l.a < 6 ORDER BY l.a;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: l.a, t.*
Relations: (public.remote_tbl l) LEFT JOIN ((public.remote_tbl r) INNER JOIN (ROWS FROM (pg_catalog.unnest(), pg_catalog.unnest()) t))
Remote SQL: SELECT r1.a, CASE WHEN (f3.*)::text IS NOT NULL THEN ROW(f3.c1, f3.c2) END FROM (public.base_tbl_fn r1 LEFT JOIN (public.base_tbl_fn r2 INNER JOIN ROWS FROM (unnest('{2,4}'::integer[]), unnest('{20,40}'::integer[])) f3(c1, c2) ON (((r2.a = f3.c1)))) ON (((r1.a = r2.a)))) WHERE ((r1.a < 6)) ORDER BY r1.a ASC NULLS LAST
(4 rows)
SELECT l.a, t FROM remote_tbl l
LEFT JOIN (remote_tbl r JOIN unnest(array[2, 4], array[20, 40]) AS t(x, y)
ON r.a = t.x)
ON l.a = r.a
WHERE l.a < 6 ORDER BY l.a;
a | t
---+--------
1 |
2 | (2,20)
3 |
4 | (4,40)
5 |
(5 rows)
RESET enable_hashjoin;
RESET enable_mergejoin;
RESET enable_nestloop;
-- Check foreign join with parameterized function
CREATE OR REPLACE FUNCTION f(int) RETURNS SETOF int LANGUAGE plpgsql ROWS 10 AS 'BEGIN RETURN QUERY SELECT generate_series(1,$1) ; END' IMMUTABLE;
ALTER EXTENSION postgres_fdw ADD FUNCTION f(INTEGER);
-- The correlated subquery keeps r1 in an enclosing query level, so the
-- function argument reaches the remote side as a query parameter. The
-- restriction on the function's own column is pushed down as well.
EXPLAIN (VERBOSE, COSTS OFF)
SELECT r1.a FROM remote_tbl r1
WHERE EXISTS (SELECT 1 FROM remote_tbl r2, f(r1.a) g
WHERE r2.a = g AND g > 20);
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.remote_tbl r1
Output: r1.a
Filter: EXISTS(SubPlan exists_1)
Remote SQL: SELECT a FROM public.base_tbl_fn
SubPlan exists_1
-> Foreign Scan
Relations: (public.remote_tbl r2) INNER JOIN (public.f() g)
Remote SQL: SELECT NULL FROM (public.base_tbl_fn r1 INNER JOIN public.f($1::integer) f2(c1) ON (((r1.a = f2.c1)) AND ((f2.c1 > 20))))
(8 rows)
SELECT r1.a FROM remote_tbl r1
WHERE EXISTS (SELECT 1 FROM remote_tbl r2, f(r1.a) g
WHERE r2.a = g AND g > 20)
ORDER BY r1.a;
a
----
21
22
23
24
25
26
27
28
29
30
(10 rows)
ALTER EXTENSION postgres_fdw DROP FUNCTION f(INTEGER);
DROP FUNCTION f(INTEGER);
-- 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

642
contrib/postgres_fdw/postgres_fdw.c
View File

@@ -30,6 +30,7 @@
#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"
@@ -90,6 +91,22 @@ 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,
};
/*
@@ -126,6 +143,11 @@ 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
{
@@ -137,6 +159,10 @@ 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,
};
/*
@@ -619,6 +645,9 @@ 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,
@@ -772,7 +801,7 @@ postgresGetForeignRelSize(PlannerInfo *root,
* Identify which baserestrictinfo clauses can be sent to the remote
* server and which can't.
*/
classifyConditions(root, baserel, baserel->baserestrictinfo,
classifyConditions(root, baserel, fpinfo, baserel->baserestrictinfo,
&fpinfo->remote_conds, &fpinfo->local_conds);
/*
@@ -1176,7 +1205,7 @@ postgresGetForeignPaths(PlannerInfo *root,
continue;
/* See if it is safe to send to remote */
if (!is_foreign_expr(root, baserel, rinfo->clause))
if (!is_foreign_expr(root, baserel, fpinfo, rinfo->clause))
continue;
/* Calculate required outer rels for the resulting path */
@@ -1252,7 +1281,7 @@ postgresGetForeignPaths(PlannerInfo *root,
continue;
/* See if it is safe to send to remote */
if (!is_foreign_expr(root, baserel, rinfo->clause))
if (!is_foreign_expr(root, baserel, fpinfo, rinfo->clause))
continue;
/* Calculate required outer rels for the resulting path */
@@ -1392,7 +1421,7 @@ postgresGetForeignPlan(PlannerInfo *root,
remote_exprs = lappend(remote_exprs, rinfo->clause);
else if (list_member_ptr(fpinfo->local_conds, rinfo))
local_exprs = lappend(local_exprs, rinfo->clause);
else if (is_foreign_expr(root, foreignrel, rinfo->clause))
else if (is_foreign_expr(root, foreignrel, fpinfo, rinfo->clause))
remote_exprs = lappend(remote_exprs, rinfo->clause);
else
local_exprs = lappend(local_exprs, rinfo->clause);
@@ -1513,9 +1542,26 @@ 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.
@@ -1536,9 +1582,15 @@ 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;
@@ -1574,13 +1626,67 @@ 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)
{
/*
* 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, ...).
*
* For an upperrel scan (the only path that reaches here)
* postgresGetForeignPlan always builds rtfuncdata via
* get_functions_data(), so it is never NIL; the per-RTE slot for
* the function RTE referenced by this Var must likewise be
* populated.
*/
List *funcdata;
TupleDesc rte_tupdesc;
int num_funcs;
int attnum;
ListCell *lc1,
*lc2;
Assert(rtfuncdata != NIL);
funcdata = list_nth(rtfuncdata, var->varno - rtoffset);
Assert(funcdata != NIL);
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;
/* get_functions_data() already validated the return type. */
Assert(OidIsValid(funcrettype) && funcrettype != RECORDOID);
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;
}
@@ -1616,14 +1722,30 @@ 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);
@@ -1666,8 +1788,19 @@ 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);
@@ -2615,7 +2748,7 @@ postgresPlanDirectModify(PlannerInfo *root,
if (attno <= InvalidAttrNumber) /* shouldn't happen */
elog(ERROR, "system-column update is not supported");
if (!is_foreign_expr(root, foreignrel, (Expr *) tle->expr))
if (!is_foreign_expr(root, foreignrel, fpinfo, (Expr *) tle->expr))
return false;
}
}
@@ -2702,6 +2835,10 @@ 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.
@@ -2815,7 +2952,26 @@ 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);
@@ -2928,7 +3084,8 @@ 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;
@@ -2978,25 +3135,90 @@ postgresExplainForeignScan(ForeignScanState *node, ExplainState *es)
rti += rtoffset;
Assert(bms_is_member(rti, plan->fs_base_relids));
rte = rt_fetch(rti, es->rtable);
Assert(rte->rtekind == RTE_RELATION);
/* This logic should agree with explain.c's ExplainTargetRel */
relname = get_rel_name(rte->relid);
if (es->verbose)
{
char *namespace;
namespace = get_namespace_name_or_temp(get_rel_namespace(rte->relid));
appendStringInfo(&relations, "%s.%s",
quote_identifier(namespace),
quote_identifier(relname));
if (rte->rtekind == RTE_FUNCTION)
{
List *rtfuncdata = list_nth(fdw_private, FdwScanPrivateFunctions);
List *funcdata;
bool multi_func;
bool first = true;
ListCell *lc;
funcdata = list_nth(rtfuncdata, rti - rtoffset);
multi_func = list_length(funcdata) > 1;
if (multi_func)
appendStringInfoString(&relations, "ROWS FROM (");
foreach(lc, funcdata)
{
List *funcinfo;
Oid funcid;
if (!first)
appendStringInfoString(&relations, ", ");
funcinfo = (List *) lfirst(lc);
funcid = linitial_node(Integer, funcinfo)->ival;
/* Checked by function_rte_pushdown_ok() */
Assert(OidIsValid(funcid));
/* Match RTE_RELATION behavior */
relname = get_func_name(funcid);
if (relname == NULL)
elog(ERROR, "cache lookup failed for function %u", funcid);
if (es->verbose)
{
char *namespace;
Oid nsoid = get_func_namespace(funcid);
namespace = get_namespace_name(nsoid);
if (namespace == NULL)
elog(ERROR, "cache lookup failed for namespace %u", nsoid);
appendStringInfo(&relations, "%s.%s()",
quote_identifier(namespace),
quote_identifier(relname));
}
else
appendStringInfo(&relations, "%s()", quote_identifier(relname));
first = false;
}
/* Close ROWS FROM */
if (multi_func)
appendStringInfoChar(&relations, ')');
}
else
appendStringInfoString(&relations,
quote_identifier(relname));
{
Assert(rte->rtekind == RTE_RELATION);
/*
* This logic should agree with explain.c's
* ExplainTargetRel
*/
relname = get_rel_name(rte->relid);
if (es->verbose)
{
char *namespace;
namespace = get_namespace_name_or_temp(get_rel_namespace(rte->relid));
appendStringInfo(&relations, "%s.%s",
quote_identifier(namespace),
quote_identifier(relname));
}
else
appendStringInfoString(&relations,
quote_identifier(relname));
}
refname = (char *) list_nth(es->rtable_names, rti - 1);
if (refname == NULL)
refname = rte->eref->aliasname;
if (strcmp(refname, relname) != 0)
if (relname == NULL || strcmp(refname, relname) != 0)
appendStringInfo(&relations, " %s",
quote_identifier(refname));
}
@@ -3220,7 +3442,7 @@ estimate_path_cost_size(PlannerInfo *root,
* param_join_conds might contain both clauses that are safe to send
* across, and clauses that aren't.
*/
classifyConditions(root, foreignrel, param_join_conds,
classifyConditions(root, foreignrel, fpinfo, param_join_conds,
&remote_param_join_conds, &local_param_join_conds);
/* Build the list of columns to be fetched from the foreign server. */
@@ -3353,8 +3575,17 @@ 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;
@@ -6564,6 +6795,257 @@ 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 two Integer nodes:
* (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;
get_expr_result_type(rtfunc->funcexpr, &funcrettype, &tupdesc);
/*
* function_rte_pushdown_ok() already rejected any function that
* doesn't return a well-defined scalar type, so this is a mere
* cross-check.
*/
Assert(OidIsValid(funcrettype) && funcrettype != RECORDOID);
funccollation = exprCollation(rtfunc->funcexpr);
funcid = ((FuncExpr *) rtfunc->funcexpr)->funcid;
funcdata = lappend(funcdata,
list_make3(makeInteger(funcid),
makeInteger(funcrettype),
makeInteger(funccollation)));
}
rtfuncdata = lappend(rtfuncdata, funcdata);
}
return rtfuncdata;
}
/*
* init_func_stub_fpinfo
* Build a stub PgFdwRelationInfo for a FUNCTION RTE that is being
* absorbed into a foreign join.
*
* A function RTE has no fdw_private of its own, but the joinrel-level cost
* estimator, deparser and merge_fdw_options() all read server-level options
* from the "outer" fpinfo unconditionally. So the stub must carry the same
* server, shippable_extensions, and cost-related options as the real foreign
* side of the join; otherwise the pushdown path is judged against zeroed
* fdw_startup_cost/fdw_tuple_cost/etc. and looks artificially cheap.
*
* The stub is meaningful only for the specific (foreign, function) pairing
* that produced it; it must live on the joinrel's PgFdwRelationInfo, never
* on the function rel's fdw_private, since the same function RTE may pair
* with different foreign servers in sibling joinrels.
*/
static PgFdwRelationInfo *
init_func_stub_fpinfo(const PgFdwRelationInfo *fpinfo_foreign,
RelOptInfo *funcrel)
{
PgFdwRelationInfo *stub = palloc0_object(PgFdwRelationInfo);
stub->pushdown_safe = true;
/* Server-level options, inherited from the foreign side. */
stub->server = fpinfo_foreign->server;
stub->shippable_extensions = fpinfo_foreign->shippable_extensions;
stub->fdw_startup_cost = fpinfo_foreign->fdw_startup_cost;
stub->fdw_tuple_cost = fpinfo_foreign->fdw_tuple_cost;
stub->use_remote_estimate = fpinfo_foreign->use_remote_estimate;
stub->fetch_size = fpinfo_foreign->fetch_size;
stub->async_capable = fpinfo_foreign->async_capable;
/* Function-side identity and estimates from the local planner. */
stub->relation_name = psprintf("%u", funcrel->relid);
stub->rows = funcrel->rows;
stub->width = funcrel->reltarget->width;
stub->retrieved_rows = funcrel->rows;
/*
* The function is executed on the remote server, so these must carry its
* cost the same way a foreign rel's do: what producing the rows costs the
* far side, before connection setup and data transfer are added. The
* local path for the same function is our best estimate of that.
*/
stub->rel_startup_cost = funcrel->cheapest_total_path->startup_cost;
stub->rel_total_cost = funcrel->cheapest_total_path->total_cost;
return stub;
}
/*
* 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);
/*
* build_simple_rel() copies rtekind straight from the RTE, so for a base
* rel rel->rtekind always matches the RTE's; the check above is therefore
* sufficient.
*/
Assert(rte->rtekind == RTE_FUNCTION);
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.
*
* Note this rejects only lateral references to another relation at the
* same query level. A function argument referencing an outer query level
* (e.g. f(outer.col) inside a subquery) is a different case: it becomes a
* PARAM_EXEC Param, the function rel's lateral_relids is empty, and
* foreign_expr_walker() intentionally treats PARAM_EXEC as shippable. The
* remote query then carries a parameter placeholder, and postgres_fdw's
* ordinary parameter machinery re-sends it on each rescan -- i.e. it
* works as a normal parameterized foreign scan, which is fine.
*/
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;
/* Refuse to deal with strange funcexprs */
if (!IsA(rtfunc->funcexpr, FuncExpr))
return false;
if (!OidIsValid(((FuncExpr *) rtfunc->funcexpr)->funcid))
return false;
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, fdwrel->fdw_private, (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
@@ -6579,6 +7061,8 @@ 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.
@@ -6597,15 +7081,68 @@ 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 = init_func_stub_fpinfo(fpinfo_o, innerrel);
/*
* Classify the function rel's own baserestrictinfo now, so that the
* local_conds check below can bail out if any of it is unshippable.
* We classify against the stub, not the joinrel's fpinfo, because the
* latter's server/shippable_extensions aren't populated until
* merge_fdw_options() runs further down.
*/
classifyConditions(root, innerrel, fpinfo_i, innerrel->baserestrictinfo,
&fpinfo_i->remote_conds, &fpinfo_i->local_conds);
fpinfo->inner_func_fpinfo = fpinfo_i;
}
else if (outer_is_function)
{
fpinfo_o = init_func_stub_fpinfo(fpinfo_i, outerrel);
/* See the comment in the inner_is_function branch above. */
classifyConditions(root, outerrel, fpinfo_o, outerrel->baserestrictinfo,
&fpinfo_o->remote_conds, &fpinfo_o->local_conds);
fpinfo->outer_func_fpinfo = fpinfo_o;
}
/*
* If joining relations have local conditions, those conditions are
@@ -6643,7 +7180,7 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
foreach(lc, extra->restrictlist)
{
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
bool is_remote_clause = is_foreign_expr(root, joinrel,
bool is_remote_clause = is_foreign_expr(root, joinrel, fpinfo,
rinfo->clause);
if (IS_OUTER_JOIN(jointype) &&
@@ -7341,7 +7878,7 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
* If any GROUP BY expression is not shippable, then we cannot
* push down aggregation to the foreign server.
*/
if (!is_foreign_expr(root, grouped_rel, expr))
if (!is_foreign_expr(root, grouped_rel, fpinfo, expr))
return false;
/*
@@ -7369,7 +7906,7 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
* Non-grouping expression we need to compute. Can we ship it
* as-is to the foreign server?
*/
if (is_foreign_expr(root, grouped_rel, expr) &&
if (is_foreign_expr(root, grouped_rel, fpinfo, expr) &&
!is_foreign_param(root, grouped_rel, expr))
{
/* Yes, so add to tlist as-is; OK to suppress duplicates */
@@ -7389,7 +7926,7 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
* don't have to check is_foreign_param, since that certainly
* won't return true for any such expression.)
*/
if (!is_foreign_expr(root, grouped_rel, (Expr *) aggvars))
if (!is_foreign_expr(root, grouped_rel, fpinfo, (Expr *) aggvars))
return false;
/*
@@ -7441,7 +7978,7 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
grouped_rel->relids,
NULL,
NULL);
if (is_foreign_expr(root, grouped_rel, expr))
if (is_foreign_expr(root, grouped_rel, fpinfo, expr))
fpinfo->remote_conds = lappend(fpinfo->remote_conds, rinfo);
else
fpinfo->local_conds = lappend(fpinfo->local_conds, rinfo);
@@ -7478,7 +8015,7 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
*/
if (IsA(expr, Aggref))
{
if (!is_foreign_expr(root, grouped_rel, expr))
if (!is_foreign_expr(root, grouped_rel, fpinfo, expr))
return false;
tlist = add_to_flat_tlist(tlist, list_make1(expr));
@@ -7991,8 +8528,8 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
* Also, the LIMIT/OFFSET cannot be pushed down, if their expressions are
* not safe to remote.
*/
if (!is_foreign_expr(root, input_rel, (Expr *) parse->limitOffset) ||
!is_foreign_expr(root, input_rel, (Expr *) parse->limitCount))
if (!is_foreign_expr(root, input_rel, ifpinfo, (Expr *) parse->limitOffset) ||
!is_foreign_expr(root, input_rel, ifpinfo, (Expr *) parse->limitCount))
return;
/* Safe to push down */
@@ -8638,7 +9175,7 @@ find_em_for_rel(PlannerInfo *root, EquivalenceClass *ec, RelOptInfo *rel)
if (bms_is_subset(em->em_relids, rel->relids) &&
!bms_is_empty(em->em_relids) &&
bms_is_empty(bms_intersect(em->em_relids, fpinfo->hidden_subquery_rels)) &&
is_foreign_expr(root, rel, em->em_expr))
is_foreign_expr(root, rel, fpinfo, em->em_expr))
return em;
}
@@ -8660,6 +9197,7 @@ EquivalenceMember *
find_em_for_rel_target(PlannerInfo *root, EquivalenceClass *ec,
RelOptInfo *rel)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
PathTarget *target = rel->reltarget;
ListCell *lc1;
int i;
@@ -8709,7 +9247,7 @@ find_em_for_rel_target(PlannerInfo *root, EquivalenceClass *ec,
continue;
/* Check that expression (including relabels!) is shippable */
if (is_foreign_expr(root, rel, em->em_expr))
if (is_foreign_expr(root, rel, fpinfo, em->em_expr))
return em;
}

12
contrib/postgres_fdw/postgres_fdw.h
View File

@@ -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;
@@ -183,11 +193,13 @@ extern char *pgfdw_application_name;
/* in deparse.c */
extern void classifyConditions(PlannerInfo *root,
RelOptInfo *baserel,
PgFdwRelationInfo *fpinfo,
List *input_conds,
List **remote_conds,
List **local_conds);
extern bool is_foreign_expr(PlannerInfo *root,
RelOptInfo *baserel,
PgFdwRelationInfo *fpinfo,
Expr *expr);
extern bool is_foreign_param(PlannerInfo *root,
RelOptInfo *baserel,

274
contrib/postgres_fdw/sql/postgres_fdw.sql
View File

@@ -825,6 +825,280 @@ 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;
-- STABLE function must NOT be pushed down either: even though its result is
-- constant within one query, evaluating it on the remote server could yield
-- a different value than evaluating it locally.
CREATE FUNCTION f_stable(int) RETURNS SETOF int LANGUAGE plpgsql STABLE AS
$$ BEGIN RETURN QUERY SELECT generate_series(1, $1); END $$;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1 FROM ft1 t1, f_stable(4) AS g(id) WHERE t1.c1 = g.id;
DROP FUNCTION f_stable(int);
-- 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;
-- Function RTE is restricted, shippable conditions
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n and n > 3;
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
WHERE r.a = n and n > 3 ORDER BY r.a;
-- Function RTE is restricted, nonshippable conditions
CREATE FUNCTION f_local(int) RETURNS int AS $$
BEGIN
RETURN $1;
END
$$ LANGUAGE plpgsql;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n and n > f_local(3);
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
WHERE r.a = n and n > f_local(3) ORDER BY r.a;
DROP FUNCTION f_local(int);
-- Check that a qual on the function RTE using a function from a shippable
-- extension is pushed down. plpgsql (not inlined) with the column as
-- argument (not const-folded) keeps the function call in the qual.
CREATE FUNCTION f_ext(int) RETURNS int AS $$
BEGIN RETURN $1; END
$$ LANGUAGE plpgsql IMMUTABLE;
ALTER EXTENSION postgres_fdw ADD FUNCTION f_ext(int);
-- Force pushdown so the fixed-code plan is deterministically a Foreign
-- Scan; on the unfixed code the qual is classified local, the join is
-- refused, and the plan falls back to a local join instead.
SET enable_hashjoin = off;
SET enable_mergejoin = off;
SET enable_nestloop = off;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r WHERE r.a = n and f_ext(n) > 3;
SELECT * FROM unnest(array[2, 3, 4]) n, remote_tbl r
WHERE r.a = n and f_ext(n) > 3 ORDER BY r.a;
RESET enable_hashjoin;
RESET enable_mergejoin;
RESET enable_nestloop;
ALTER EXTENSION postgres_fdw DROP FUNCTION f_ext(int);
DROP FUNCTION f_ext(int);
-- 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;
-- Same nullable-side whole-row Var, but with outer rows that both match
-- and miss the (foreign x function) inner join. A multi-column function
-- RTE is used so that the reference is a genuine whole-row Var (a single
-- scalar-returning function would collapse to its lone column). This
-- exercises the THEN ROW(...) side of deparseColumnRef()'s whole-row CASE
-- (matched rows reconstruct the composite) as well as the NULL side
-- (missed rows), confirming the executor rebuilds the anonymous composite
-- correctly.
EXPLAIN (VERBOSE, COSTS OFF)
SELECT l.a, t FROM remote_tbl l
LEFT JOIN (remote_tbl r JOIN unnest(array[2, 4], array[20, 40]) AS t(x, y)
ON r.a = t.x)
ON l.a = r.a
WHERE l.a < 6 ORDER BY l.a;
SELECT l.a, t FROM remote_tbl l
LEFT JOIN (remote_tbl r JOIN unnest(array[2, 4], array[20, 40]) AS t(x, y)
ON r.a = t.x)
ON l.a = r.a
WHERE l.a < 6 ORDER BY l.a;
RESET enable_hashjoin;
RESET enable_mergejoin;
RESET enable_nestloop;
-- Check foreign join with parameterized function
CREATE OR REPLACE FUNCTION f(int) RETURNS SETOF int LANGUAGE plpgsql ROWS 10 AS 'BEGIN RETURN QUERY SELECT generate_series(1,$1) ; END' IMMUTABLE;
ALTER EXTENSION postgres_fdw ADD FUNCTION f(INTEGER);
-- The correlated subquery keeps r1 in an enclosing query level, so the
-- function argument reaches the remote side as a query parameter. The
-- restriction on the function's own column is pushed down as well.
EXPLAIN (VERBOSE, COSTS OFF)
SELECT r1.a FROM remote_tbl r1
WHERE EXISTS (SELECT 1 FROM remote_tbl r2, f(r1.a) g
WHERE r2.a = g AND g > 20);
SELECT r1.a FROM remote_tbl r1
WHERE EXISTS (SELECT 1 FROM remote_tbl r2, f(r1.a) g
WHERE r2.a = g AND g > 20)
ORDER BY r1.a;
ALTER EXTENSION postgres_fdw DROP FUNCTION f(INTEGER);
DROP FUNCTION f(INTEGER);
-- 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

18
doc/src/sgml/postgres-fdw.sgml
View File

@@ -1200,6 +1200,24 @@ CREATE SUBSCRIPTION my_subscription SERVER subscription_server PUBLICATION testp
<literal>WHERE</literal> clauses.
</para>
<para>
An <literal>INNER JOIN</literal> between a foreign table and a set-returning
function appearing as a <literal>FROM</literal>-list item can likewise be
pushed down: the function call is absorbed into the remote query so that
only rows matching the function's output are fetched. This is attempted
only when the function is <literal>IMMUTABLE</literal> (so evaluating it on
the remote server is guaranteed to produce the same result as evaluating
it locally), its arguments and any restriction clauses on it are
shippable, and none of the following disqualifying conditions applies:
the join type is not <literal>INNER</literal>; the function is used with
<literal>WITH ORDINALITY</literal>; the function returns a
<type>record</type> type without an accompanying column definition list;
or the function laterally references another relation at the same query
level. A function argument that is a parameter from an enclosing query
level is allowed and is transmitted to the remote server as a query
parameter.
</para>
<para>
The query that is actually sent to the remote server for execution can
be examined using <command>EXPLAIN VERBOSE</command>.

25
src/backend/optimizer/util/relnode.c
View File

@@ -746,6 +746,31 @@ 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)
{
/* Same as just above, with the two sides swapped. */
joinrel->serverid = inner_rel->serverid;
joinrel->userid = inner_rel->userid;
joinrel->useridiscurrent = inner_rel->useridiscurrent;
joinrel->fdwroutine = inner_rel->fdwroutine;
}
}
/*