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hlinnakahlinnaka
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Support OID system column in postgres_fdw.
You can use ALTER FOREIGN TABLE SET WITH OIDS on a foreign table, but the oid column read out as zeros, because the postgres_fdw didn't know about it. Teach postgres_fdw how to fetch it. Etsuro Fujita, with an additional test case by me. Discussion: <56E90A76.5000503@lab.ntt.co.jp>
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4 files changed

+101
-20
lines changed

4 files changed

+101
-20
lines changed

‎contrib/postgres_fdw/deparse.c‎

Lines changed: 30 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -287,13 +287,14 @@ foreign_expr_walker(Node *node,
287287
/* Var belongs to foreign table */
288288

289289
/*
290-
* System columns other than ctid should not be sent to
291-
* the remote, since we don't make any effort to ensure
292-
* that local and remote values match (tableoid, in
290+
* System columns other than ctid and oid should not be
291+
* sent to the remote, since we don't make any effort to
292+
* ensure that local and remote values match (tableoid, in
293293
* particular, almost certainly doesn't match).
294294
*/
295295
if (var->varattno < 0 &&
296-
var->varattno != SelfItemPointerAttributeNumber)
296+
var->varattno != SelfItemPointerAttributeNumber &&
297+
var->varattno != ObjectIdAttributeNumber)
297298
return false;
298299

299300
/* Else check the collation */
@@ -913,8 +914,8 @@ deparseTargetList(StringInfo buf,
913914
}
914915

915916
/*
916-
* Add ctid if needed. We currently don't support retrieving any other
917-
* system columns.
917+
* Add ctid and oid if needed. We currently don't support retrieving any
918+
* other system columns.
918919
*/
919920
if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber,
920921
attrs_used))
@@ -932,6 +933,22 @@ deparseTargetList(StringInfo buf,
932933
*retrieved_attrs = lappend_int(*retrieved_attrs,
933934
SelfItemPointerAttributeNumber);
934935
}
936+
if (bms_is_member(ObjectIdAttributeNumber - FirstLowInvalidHeapAttributeNumber,
937+
attrs_used))
938+
{
939+
if (!first)
940+
appendStringInfoString(buf, ", ");
941+
else if (is_returning)
942+
appendStringInfoString(buf, " RETURNING ");
943+
first = false;
944+
945+
if (qualify_col)
946+
ADD_REL_QUALIFIER(buf, rtindex);
947+
appendStringInfoString(buf, "oid");
948+
949+
*retrieved_attrs = lappend_int(*retrieved_attrs,
950+
ObjectIdAttributeNumber);
951+
}
935952

936953
/* Don't generate bad syntax if no undropped columns */
937954
if (first && !is_returning)
@@ -1574,13 +1591,19 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
15741591
{
15751592
RangeTblEntry *rte;
15761593

1594+
/* We support fetching the remote side's CTID and OID. */
15771595
if (varattno == SelfItemPointerAttributeNumber)
15781596
{
1579-
/* We support fetching the remote side's CTID. */
15801597
if (qualify_col)
15811598
ADD_REL_QUALIFIER(buf, varno);
15821599
appendStringInfoString(buf, "ctid");
15831600
}
1601+
else if (varattno == ObjectIdAttributeNumber)
1602+
{
1603+
if (qualify_col)
1604+
ADD_REL_QUALIFIER(buf, varno);
1605+
appendStringInfoString(buf, "oid");
1606+
}
15841607
else if (varattno < 0)
15851608
{
15861609
/*

‎contrib/postgres_fdw/expected/postgres_fdw.out‎

Lines changed: 33 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -124,6 +124,13 @@ CREATE FOREIGN TABLE ft6 (
124124
c2 int NOT NULL,
125125
c3 text
126126
) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 4');
127+
-- A table with oids. CREATE FOREIGN TABLE doesn't support the
128+
-- WITH OIDS option, but ALTER does.
129+
CREATE FOREIGN TABLE ft_pg_type (
130+
typname name,
131+
typlen smallint
132+
) SERVER loopback OPTIONS (schema_name 'pg_catalog', table_name 'pg_type');
133+
ALTER TABLE ft_pg_type SET WITH OIDS;
127134
-- ===================================================================
128135
-- tests for validator
129136
-- ===================================================================
@@ -173,15 +180,16 @@ ALTER FOREIGN TABLE ft2 OPTIONS (schema_name 'S 1', table_name 'T 1');
173180
ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
174181
ALTER FOREIGN TABLE ft2 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
175182
\det+
176-
List of foreign tables
177-
Schema | Table | Server | FDW Options | Description
178-
--------+-------+-----------+---------------------------------------+-------------
179-
public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') |
180-
public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') |
181-
public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') |
182-
public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') |
183-
public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') |
184-
(5 rows)
183+
List of foreign tables
184+
Schema | Table | Server | FDW Options | Description
185+
--------+------------+-----------+--------------------------------------------------+-------------
186+
public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') |
187+
public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') |
188+
public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') |
189+
public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') |
190+
public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') |
191+
public | ft_pg_type | loopback | (schema_name 'pg_catalog', table_name 'pg_type') |
192+
(6 rows)
185193

186194
-- Now we should be able to run ANALYZE.
187195
-- To exercise multiple code paths, we use local stats on ft1
@@ -2485,7 +2493,7 @@ DEALLOCATE st2;
24852493
DEALLOCATE st3;
24862494
DEALLOCATE st4;
24872495
DEALLOCATE st5;
2488-
-- System columns, except ctid, should not be sent to remote
2496+
-- System columns, except ctid and oid, should not be sent to remote
24892497
EXPLAIN (VERBOSE, COSTS OFF)
24902498
SELECT * FROM ft1 t1 WHERE t1.tableoid = 'pg_class'::regclass LIMIT 1;
24912499
QUERY PLAN
@@ -2553,6 +2561,21 @@ SELECT ctid, * FROM ft1 t1 LIMIT 1;
25532561
(0,1) | 1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
25542562
(1 row)
25552563

2564+
EXPLAIN (VERBOSE, COSTS OFF)
2565+
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
2566+
QUERY PLAN
2567+
----------------------------------------------------------------------------------------------------
2568+
Foreign Scan on public.ft_pg_type
2569+
Output: oid, typname, typlen
2570+
Remote SQL: SELECT typname, typlen, oid FROM pg_catalog.pg_type WHERE ((typname = 'int4'::name))
2571+
(3 rows)
2572+
2573+
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
2574+
oid | typname | typlen
2575+
-----+---------+--------
2576+
23 | int4 | 4
2577+
(1 row)
2578+
25562579
-- ===================================================================
25572580
-- used in pl/pgsql function
25582581
-- ===================================================================

‎contrib/postgres_fdw/postgres_fdw.c‎

Lines changed: 26 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -4374,6 +4374,7 @@ make_tuple_from_result_row(PGresult *res,
43744374
Datum *values;
43754375
bool *nulls;
43764376
ItemPointer ctid = NULL;
4377+
Oid oid = InvalidOid;
43774378
ConversionLocation errpos;
43784379
ErrorContextCallback errcallback;
43794380
MemoryContext oldcontext;
@@ -4431,7 +4432,11 @@ make_tuple_from_result_row(PGresult *res,
44314432
else
44324433
valstr = PQgetvalue(res, row, j);
44334434

4434-
/* convert value to internal representation */
4435+
/*
4436+
* convert value to internal representation
4437+
*
4438+
* Note: we ignore system columns other than ctid and oid in result
4439+
*/
44354440
errpos.cur_attno = i;
44364441
if (i > 0)
44374442
{
@@ -4446,7 +4451,7 @@ make_tuple_from_result_row(PGresult *res,
44464451
}
44474452
else if (i == SelfItemPointerAttributeNumber)
44484453
{
4449-
/* ctid --- note we ignore any other system column in result */
4454+
/* ctid */
44504455
if (valstr != NULL)
44514456
{
44524457
Datum datum;
@@ -4455,6 +4460,17 @@ make_tuple_from_result_row(PGresult *res,
44554460
ctid = (ItemPointer) DatumGetPointer(datum);
44564461
}
44574462
}
4463+
else if (i == ObjectIdAttributeNumber)
4464+
{
4465+
/* oid */
4466+
if (valstr != NULL)
4467+
{
4468+
Datum datum;
4469+
4470+
datum = DirectFunctionCall1(oidin, CStringGetDatum(valstr));
4471+
oid = DatumGetObjectId(datum);
4472+
}
4473+
}
44584474
errpos.cur_attno = 0;
44594475

44604476
j++;
@@ -4498,6 +4514,12 @@ make_tuple_from_result_row(PGresult *res,
44984514
HeapTupleHeaderSetXmin(tuple->t_data, InvalidTransactionId);
44994515
HeapTupleHeaderSetCmin(tuple->t_data, InvalidTransactionId);
45004516

4517+
/*
4518+
* If we have an OID to return, install it.
4519+
*/
4520+
if (OidIsValid(oid))
4521+
HeapTupleSetOid(tuple, oid);
4522+
45014523
/* Clean up */
45024524
MemoryContextReset(temp_context);
45034525

@@ -4525,6 +4547,8 @@ conversion_error_callback(void *arg)
45254547
attname = NameStr(tupdesc->attrs[errpos->cur_attno - 1]->attname);
45264548
else if (errpos->cur_attno == SelfItemPointerAttributeNumber)
45274549
attname = "ctid";
4550+
else if (errpos->cur_attno == ObjectIdAttributeNumber)
4551+
attname = "oid";
45284552

45294553
relname = RelationGetRelationName(errpos->rel);
45304554
}

‎contrib/postgres_fdw/sql/postgres_fdw.sql‎

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -136,6 +136,14 @@ CREATE FOREIGN TABLE ft6 (
136136
c3 text
137137
) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 4');
138138

139+
-- A table with oids. CREATE FOREIGN TABLE doesn't support the
140+
-- WITH OIDS option, but ALTER does.
141+
CREATE FOREIGN TABLE ft_pg_type (
142+
typname name,
143+
typlen smallint
144+
) SERVER loopback OPTIONS (schema_name 'pg_catalog', table_name 'pg_type');
145+
ALTER TABLE ft_pg_type SET WITH OIDS;
146+
139147
-- ===================================================================
140148
-- tests for validator
141149
-- ===================================================================
@@ -577,7 +585,7 @@ DEALLOCATE st3;
577585
DEALLOCATE st4;
578586
DEALLOCATE st5;
579587

580-
-- System columns, except ctid, should not be sent to remote
588+
-- System columns, except ctid and oid, should not be sent to remote
581589
EXPLAIN (VERBOSE, COSTS OFF)
582590
SELECT * FROM ft1 t1 WHERE t1.tableoid = 'pg_class'::regclass LIMIT 1;
583591
SELECT * FROM ft1 t1 WHERE t1.tableoid = 'ft1'::regclass LIMIT 1;
@@ -590,6 +598,9 @@ SELECT * FROM ft1 t1 WHERE t1.ctid = '(0,2)';
590598
EXPLAIN (VERBOSE, COSTS OFF)
591599
SELECT ctid, * FROM ft1 t1 LIMIT 1;
592600
SELECT ctid, * FROM ft1 t1 LIMIT 1;
601+
EXPLAIN (VERBOSE, COSTS OFF)
602+
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
603+
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
593604

594605
-- ===================================================================
595606
-- used in pl/pgsql function

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