From da7d44b627ba839de32c9409aca659f60324de76 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 15 Apr 2016 11:58:56 -0400
Subject: [PATCH] postgres_fdw: Clean up handling of system columns.
Previously, querying the xmin column of a single postgres_fdw foreign
table fetched the tuple length, xmax the typmod, and cmin or cmax the
composite type OID of the tuple. However, when you queried several
such tables and the join got shipped to the remote side, these columns
ended up containing the remote values of the corresponding columns.
Both behaviors are rather unprincipled, the former for obvious reasons
and the latter because the remote values of these columns don't have
any local significance; our transaction IDs are in a different space
than those of the remote machine. Clean this up by setting all of
these fields to 0 in both cases. Also fix the handling of tableoid
to be sane.
Robert Haas and Ashutosh Bapat, reviewed by Etsuro Fujita.
---
contrib/postgres_fdw/deparse.c | 46 ++++++++++++++++++-
.../postgres_fdw/expected/postgres_fdw.out | 42 ++++++++---------
contrib/postgres_fdw/postgres_fdw.c | 12 +++++
3 files changed, 78 insertions(+), 22 deletions(-)
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index bdc410d1a35..35c27e7fb3c 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -1571,13 +1571,38 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
{
RangeTblEntry *rte;
- /* varattno can be a whole-row reference, ctid or a regular table column */
if (varattno == SelfItemPointerAttributeNumber)
{
+ /* We support fetching the remote side's CTID. */
if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);
appendStringInfoString(buf, "ctid");
}
+ else if (varattno < 0)
+ {
+ /*
+ * All other system attributes are fetched as 0, except for table OID,
+ * which is fetched as the local table OID. However, we must be
+ * careful; the table could be beneath an outer join, in which case
+ * it must go to NULL whenever the rest of the row does.
+ */
+ Oid fetchval = 0;
+
+ if (varattno == TableOidAttributeNumber)
+ {
+ rte = planner_rt_fetch(varno, root);
+ fetchval = rte->relid;
+ }
+
+ if (qualify_col)
+ {
+ appendStringInfoString(buf, "CASE WHEN ");
+ ADD_REL_QUALIFIER(buf, varno);
+ appendStringInfo(buf, "* IS NOT NULL THEN %u END", fetchval);
+ }
+ else
+ appendStringInfo(buf, "%u", fetchval);
+ }
else if (varattno == 0)
{
/* Whole row reference */
@@ -1606,10 +1631,29 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
*/
attrs_used = bms_add_member(NULL,
0 - FirstLowInvalidHeapAttributeNumber);
+
+ /*
+ * In case the whole-row reference is under an outer join then it has to
+ * go NULL whenver the rest of the row goes NULL. Deparsing a join query
+ * would always involve multiple relations, thus qualify_col would be
+ * true.
+ */
+ if (qualify_col)
+ {
+ appendStringInfoString(buf, "CASE WHEN ");
+ ADD_REL_QUALIFIER(buf, varno);
+ appendStringInfo(buf, "* IS NOT NULL THEN ");
+ }
+
appendStringInfoString(buf, "ROW(");
deparseTargetList(buf, root, varno, rel, false, attrs_used, qualify_col,
&retrieved_attrs);
appendStringInfoString(buf, ")");
+
+ /* Complete the CASE WHEN statement started above. */
+ if (qualify_col)
+ appendStringInfo(buf," END");
+
heap_close(rel, NoLock);
bms_free(attrs_used);
}
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 50f1261e63f..514d83478d9 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -1375,8 +1375,8 @@ SELECT t1.c1, t2.c1 FROM ft4 t1 FULL JOIN ft5 t2 ON (t1.c1 = t2.c1) WHERE (t1.c1
-- tests whole-row reference for row marks
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR UPDATE OF t1;
- QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
-> LockRows
@@ -1384,7 +1384,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
-> Foreign Scan
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
- Remote SQL: SELECT r1."C 1", r1.c3, ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8), r2."C 1", ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1
+ Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1
-> Merge Join
Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
Merge Cond: (t1.c1 = t2.c1)
@@ -1419,8 +1419,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR UPDATE;
- QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
-> LockRows
@@ -1428,7 +1428,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
-> Foreign Scan
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
- Remote SQL: SELECT r1."C 1", r1.c3, ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8), r2."C 1", ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1 FOR UPDATE OF r2
+ Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1 FOR UPDATE OF r2
-> Merge Join
Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
Merge Cond: (t1.c1 = t2.c1)
@@ -1464,8 +1464,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
-- join two tables with FOR SHARE clause
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR SHARE OF t1;
- QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
-> LockRows
@@ -1473,7 +1473,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
-> Foreign Scan
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
- Remote SQL: SELECT r1."C 1", r1.c3, ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8), r2."C 1", ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1
+ Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1
-> Merge Join
Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
Merge Cond: (t1.c1 = t2.c1)
@@ -1508,8 +1508,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR SHARE;
- QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
-> LockRows
@@ -1517,7 +1517,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
-> Foreign Scan
Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
- Remote SQL: SELECT r1."C 1", r1.c3, ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8), r2."C 1", ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1 FOR SHARE OF r2
+ Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1 FOR SHARE OF r2
-> Merge Join
Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
Merge Cond: (t1.c1 = t2.c1)
@@ -1587,14 +1587,14 @@ WITH t (c1_1, c1_3, c2_1) AS (SELECT t1.c1, t1.c3, t2.c1 FROM ft1 t1 JOIN ft2 t2
-- ctid with whole-row reference
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.ctid, t1, t2, t1.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
- QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
Output: t1.ctid, t1.*, t2.*, t1.c1, t1.c3
-> Foreign Scan
Output: t1.ctid, t1.*, t2.*, t1.c1, t1.c3
Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
- Remote SQL: SELECT r1.ctid, ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8), r1."C 1", r1.c3, ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
+ Remote SQL: SELECT r1.ctid, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r1."C 1", r1.c3, CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1."C 1" = r2."C 1")) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
(6 rows)
-- SEMI JOIN, not pushed down
@@ -2692,14 +2692,14 @@ UPDATE ft2 SET c2 = c2 + 400, c3 = c3 || '_update7' WHERE c1 % 10 = 7 RETURNING
EXPLAIN (verbose, costs off)
UPDATE ft2 SET c2 = ft2.c2 + 500, c3 = ft2.c3 || '_update9', c7 = DEFAULT
FROM ft1 WHERE ft1.c1 = ft2.c2 AND ft1.c1 % 10 = 9; -- can't be pushed down
- QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Update on public.ft2
Remote SQL: UPDATE "S 1"."T 1" SET c2 = $2, c3 = $3, c7 = $4 WHERE ctid = $1
-> Foreign Scan
Output: ft2.c1, (ft2.c2 + 500), NULL::integer, (ft2.c3 || '_update9'::text), ft2.c4, ft2.c5, ft2.c6, 'ft2 '::character(10), ft2.c8, ft2.ctid, ft1.*
Relations: (public.ft2) INNER JOIN (public.ft1)
- Remote SQL: SELECT r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c8, r1.ctid, ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 9)) FOR UPDATE OF r1
+ Remote SQL: SELECT r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c8, r1.ctid, CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 9)) FOR UPDATE OF r1
-> Hash Join
Output: ft2.c1, ft2.c2, ft2.c3, ft2.c4, ft2.c5, ft2.c6, ft2.c8, ft2.ctid, ft1.*
Hash Cond: (ft2.c2 = ft1.c1)
@@ -2835,14 +2835,14 @@ DELETE FROM ft2 WHERE c1 % 10 = 5 RETURNING c1, c4;
EXPLAIN (verbose, costs off)
DELETE FROM ft2 USING ft1 WHERE ft1.c1 = ft2.c2 AND ft1.c1 % 10 = 2; -- can't be pushed down
- QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ QUERY PLAN
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Delete on public.ft2
Remote SQL: DELETE FROM "S 1"."T 1" WHERE ctid = $1
-> Foreign Scan
Output: ft2.ctid, ft1.*
Relations: (public.ft2) INNER JOIN (public.ft1)
- Remote SQL: SELECT r1.ctid, ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 2)) FOR UPDATE OF r1
+ Remote SQL: SELECT r1.ctid, CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (TRUE)) WHERE ((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 2)) FOR UPDATE OF r1
-> Hash Join
Output: ft2.ctid, ft1.*
Hash Cond: (ft2.c2 = ft1.c1)
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index ee0220a7f70..066cffba955 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -4410,6 +4410,18 @@ make_tuple_from_result_row(PGresult *res,
if (ctid)
tuple->t_self = tuple->t_data->t_ctid = *ctid;
+ /*
+ * Stomp on the xmin, xmax, and cmin fields from the tuple created by
+ * heap_form_tuple. heap_form_tuple actually creates the tuple with
+ * DatumTupleFields, not HeapTupleFields, but the executor expects
+ * HeapTupleFields and will happily extract system columns on that
+ * assumption. If we don't do this then, for example, the tuple length
+ * ends up in the xmin field, which isn't what we want.
+ */
+ HeapTupleHeaderSetXmax(tuple->t_data, InvalidTransactionId);
+ HeapTupleHeaderSetXmin(tuple->t_data, InvalidTransactionId);
+ HeapTupleHeaderSetCmin(tuple->t_data, InvalidTransactionId);
+
/* Clean up */
MemoryContextReset(temp_context);
--
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