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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>
This commit is contained in:
Heikki Linnakangas 2016-08-26 16:33:57 +03:00
parent 2533ff0aa5
commit ae025a1598
4 changed files with 101 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
contrib/postgres_fdw/deparse.c
View File

@ -287,13 +287,14 @@ foreign_expr_walker(Node *node,
/* Var belongs to foreign table */
/*
* System columns other than ctid should not be sent to
* the remote, since we don't make any effort to ensure
* that local and remote values match (tableoid, in
* System columns other than ctid and oid should not be
* sent to the remote, since we don't make any effort to
* ensure that local and remote values match (tableoid, in
* particular, almost certainly doesn't match).
*/
if (var->varattno < 0 &&
var->varattno != SelfItemPointerAttributeNumber)
var->varattno != SelfItemPointerAttributeNumber &&
var->varattno != ObjectIdAttributeNumber)
return false;
/* Else check the collation */
@ -913,8 +914,8 @@ deparseTargetList(StringInfo buf,
}
/*
* Add ctid if needed. We currently don't support retrieving any other
* system columns.
* Add ctid and oid if needed. We currently don't support retrieving any
* other system columns.
*/
if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber,
attrs_used))
@ -932,6 +933,22 @@ deparseTargetList(StringInfo buf,
*retrieved_attrs = lappend_int(*retrieved_attrs,
SelfItemPointerAttributeNumber);
}
if (bms_is_member(ObjectIdAttributeNumber - FirstLowInvalidHeapAttributeNumber,
attrs_used))
{
if (!first)
appendStringInfoString(buf, ", ");
else if (is_returning)
appendStringInfoString(buf, " RETURNING ");
first = false;
if (qualify_col)
ADD_REL_QUALIFIER(buf, rtindex);
appendStringInfoString(buf, "oid");
*retrieved_attrs = lappend_int(*retrieved_attrs,
ObjectIdAttributeNumber);
}
/* Don't generate bad syntax if no undropped columns */
if (first && !is_returning)
@ -1574,13 +1591,19 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
{
RangeTblEntry *rte;
/* We support fetching the remote side's CTID and OID. */
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 == ObjectIdAttributeNumber)
{
if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);
appendStringInfoString(buf, "oid");
}
else if (varattno < 0)
{
/*

43
contrib/postgres_fdw/expected/postgres_fdw.out
View File

@ -124,6 +124,13 @@ CREATE FOREIGN TABLE ft6 (
c2 int NOT NULL,
c3 text
) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 4');
-- A table with oids. CREATE FOREIGN TABLE doesn't support the
-- WITH OIDS option, but ALTER does.
CREATE FOREIGN TABLE ft_pg_type (
typname name,
typlen smallint
) SERVER loopback OPTIONS (schema_name 'pg_catalog', table_name 'pg_type');
ALTER TABLE ft_pg_type SET WITH OIDS;
-- ===================================================================
-- tests for validator
-- ===================================================================
@ -173,15 +180,16 @@ ALTER FOREIGN TABLE ft2 OPTIONS (schema_name 'S 1', table_name 'T 1');
ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
ALTER FOREIGN TABLE ft2 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
\det+
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------+-------+-----------+---------------------------------------+-------------
public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') |
public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') |
public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') |
public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') |
public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') |
(5 rows)
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------+------------+-----------+--------------------------------------------------+-------------
public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') |
public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') |
public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') |
public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') |
public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') |
public | ft_pg_type | loopback | (schema_name 'pg_catalog', table_name 'pg_type') |
(6 rows)
-- Now we should be able to run ANALYZE.
-- To exercise multiple code paths, we use local stats on ft1
@ -2485,7 +2493,7 @@ DEALLOCATE st2;
DEALLOCATE st3;
DEALLOCATE st4;
DEALLOCATE st5;
-- System columns, except ctid, should not be sent to remote
-- System columns, except ctid and oid, should not be sent to remote
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM ft1 t1 WHERE t1.tableoid = 'pg_class'::regclass LIMIT 1;
QUERY PLAN
@ -2553,6 +2561,21 @@ SELECT ctid, * FROM ft1 t1 LIMIT 1;
(0,1) | 1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
(1 row)
EXPLAIN (VERBOSE, COSTS OFF)
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
QUERY PLAN
----------------------------------------------------------------------------------------------------
Foreign Scan on public.ft_pg_type
Output: oid, typname, typlen
Remote SQL: SELECT typname, typlen, oid FROM pg_catalog.pg_type WHERE ((typname = 'int4'::name))
(3 rows)
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
oid | typname | typlen
-----+---------+--------
23 | int4 | 4
(1 row)
-- ===================================================================
-- used in pl/pgsql function
-- ===================================================================

28
contrib/postgres_fdw/postgres_fdw.c
View File

@ -4374,6 +4374,7 @@ make_tuple_from_result_row(PGresult *res,
Datum *values;
bool *nulls;
ItemPointer ctid = NULL;
Oid oid = InvalidOid;
ConversionLocation errpos;
ErrorContextCallback errcallback;
MemoryContext oldcontext;
@ -4431,7 +4432,11 @@ make_tuple_from_result_row(PGresult *res,
else
valstr = PQgetvalue(res, row, j);
/* convert value to internal representation */
/*
* convert value to internal representation
*
* Note: we ignore system columns other than ctid and oid in result
*/
errpos.cur_attno = i;
if (i > 0)
{
@ -4446,7 +4451,7 @@ make_tuple_from_result_row(PGresult *res,
}
else if (i == SelfItemPointerAttributeNumber)
{
/* ctid --- note we ignore any other system column in result */
/* ctid */
if (valstr != NULL)
{
Datum datum;
@ -4455,6 +4460,17 @@ make_tuple_from_result_row(PGresult *res,
ctid = (ItemPointer) DatumGetPointer(datum);
}
}
else if (i == ObjectIdAttributeNumber)
{
/* oid */
if (valstr != NULL)
{
Datum datum;
datum = DirectFunctionCall1(oidin, CStringGetDatum(valstr));
oid = DatumGetObjectId(datum);
}
}
errpos.cur_attno = 0;
j++;
@ -4498,6 +4514,12 @@ make_tuple_from_result_row(PGresult *res,
HeapTupleHeaderSetXmin(tuple->t_data, InvalidTransactionId);
HeapTupleHeaderSetCmin(tuple->t_data, InvalidTransactionId);
/*
* If we have an OID to return, install it.
*/
if (OidIsValid(oid))
HeapTupleSetOid(tuple, oid);
/* Clean up */
MemoryContextReset(temp_context);
@ -4525,6 +4547,8 @@ conversion_error_callback(void *arg)
attname = NameStr(tupdesc->attrs[errpos->cur_attno - 1]->attname);
else if (errpos->cur_attno == SelfItemPointerAttributeNumber)
attname = "ctid";
else if (errpos->cur_attno == ObjectIdAttributeNumber)
attname = "oid";
relname = RelationGetRelationName(errpos->rel);
}

13
contrib/postgres_fdw/sql/postgres_fdw.sql
View File

@ -136,6 +136,14 @@ CREATE FOREIGN TABLE ft6 (
c3 text
) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 4');
-- A table with oids. CREATE FOREIGN TABLE doesn't support the
-- WITH OIDS option, but ALTER does.
CREATE FOREIGN TABLE ft_pg_type (
typname name,
typlen smallint
) SERVER loopback OPTIONS (schema_name 'pg_catalog', table_name 'pg_type');
ALTER TABLE ft_pg_type SET WITH OIDS;
-- ===================================================================
-- tests for validator
-- ===================================================================
@ -577,7 +585,7 @@ DEALLOCATE st3;
DEALLOCATE st4;
DEALLOCATE st5;
-- System columns, except ctid, should not be sent to remote
-- System columns, except ctid and oid, should not be sent to remote
EXPLAIN (VERBOSE, COSTS OFF)
SELECT * FROM ft1 t1 WHERE t1.tableoid = 'pg_class'::regclass LIMIT 1;
SELECT * FROM ft1 t1 WHERE t1.tableoid = 'ft1'::regclass LIMIT 1;
@ -590,6 +598,9 @@ SELECT * FROM ft1 t1 WHERE t1.ctid = '(0,2)';
EXPLAIN (VERBOSE, COSTS OFF)
SELECT ctid, * FROM ft1 t1 LIMIT 1;
SELECT ctid, * FROM ft1 t1 LIMIT 1;
EXPLAIN (VERBOSE, COSTS OFF)
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
SELECT oid, * FROM ft_pg_type WHERE typname = 'int4';
-- ===================================================================
-- used in pl/pgsql function