Remove WITH OIDS support, change oid catalog column visibility.

Previously tables declared WITH OIDS, including a significant fraction
of the catalog tables, stored the oid column not as a normal column,
but as part of the tuple header.

This special column was not shown by default, which was somewhat odd,
as it's often (consider e.g. pg_class.oid) one of the more important
parts of a row.  Neither pg_dump nor COPY included the contents of the
oid column by default.

The fact that the oid column was not an ordinary column necessitated a
significant amount of special case code to support oid columns. That
already was painful for the existing, but upcoming work aiming to make
table storage pluggable, would have required expanding and duplicating
that "specialness" significantly.

WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0).
Remove it.

Removing includes:
- CREATE TABLE and ALTER TABLE syntax for declaring the table to be
  WITH OIDS has been removed (WITH (oids[ = true]) will error out)
- pg_dump does not support dumping tables declared WITH OIDS and will
  issue a warning when dumping one (and ignore the oid column).
- restoring an pg_dump archive with pg_restore will warn when
  restoring a table with oid contents (and ignore the oid column)
- COPY will refuse to load binary dump that includes oids.
- pg_upgrade will error out when encountering tables declared WITH
  OIDS, they have to be altered to remove the oid column first.
- Functionality to access the oid of the last inserted row (like
  plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed.

The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false)
for CREATE TABLE) is still supported. While that requires a bit of
support code, it seems unnecessary to break applications / dumps that
do not use oids, and are explicit about not using them.

The biggest user of WITH OID columns was postgres' catalog. This
commit changes all 'magic' oid columns to be columns that are normally
declared and stored. To reduce unnecessary query breakage all the
newly added columns are still named 'oid', even if a table's column
naming scheme would indicate 'reloid' or such.  This obviously
requires adapting a lot code, mostly replacing oid access via
HeapTupleGetOid() with access to the underlying Form_pg_*->oid column.

The bootstrap process now assigns oids for all oid columns in
genbki.pl that do not have an explicit value (starting at the largest
oid previously used), only oids assigned later by oids will be above
FirstBootstrapObjectId. As the oid column now is a normal column the
special bootstrap syntax for oids has been removed.

Oids are not automatically assigned during insertion anymore, all
backend code explicitly assigns oids with GetNewOidWithIndex(). For
the rare case that insertions into the catalog via SQL are called for
the new pg_nextoid() function can be used (which only works on catalog
tables).

The fact that oid columns on system tables are now normal columns
means that they will be included in the set of columns expanded
by * (i.e. SELECT * FROM pg_class will now include the table's oid,
previously it did not). It'd not technically be hard to hide oid
column by default, but that'd mean confusing behavior would either
have to be carried forward forever, or it'd cause breakage down the
line.

While it's not unlikely that further adjustments are needed, the
scope/invasiveness of the patch makes it worthwhile to get merge this
now. It's painful to maintain externally, too complicated to commit
after the code code freeze, and a dependency of a number of other
patches.

Catversion bump, for obvious reasons.

Author: Andres Freund, with contributions by John Naylor
Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de

1 files changed, 6 insertions, 65 deletions

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index da2a8f34c20..96501456422 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2454,7 +2454,7 @@ ReleaseBulkInsertStatePin(BulkInsertState bistate)
  * TID where the tuple was stored.  But note that any toasting of fields
  * within the tuple data is NOT reflected into *tup.
  */
-Oid
+void
 heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 			int options, BulkInsertState bistate)
 {
@@ -2628,8 +2628,6 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 		tup->t_self = heaptup->t_self;
 		heap_freetuple(heaptup);
 	}
-
-	return HeapTupleGetOid(tup);
 }
 
 /*
@@ -2656,30 +2654,6 @@ heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
 				(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
 				 errmsg("cannot insert tuples in a parallel worker")));
 
-	if (relation->rd_rel->relhasoids)
-	{
-#ifdef NOT_USED
-		/* this is redundant with an Assert in HeapTupleSetOid */
-		Assert(tup->t_data->t_infomask & HEAP_HASOID);
-#endif
-
-		/*
-		 * If the object id of this tuple has already been assigned, trust the
-		 * caller.  There are a couple of ways this can happen.  At initial db
-		 * creation, the backend program sets oids for tuples. When we define
-		 * an index, we set the oid.  Finally, in the future, we may allow
-		 * users to set their own object ids in order to support a persistent
-		 * object store (objects need to contain pointers to one another).
-		 */
-		if (!OidIsValid(HeapTupleGetOid(tup)))
-			HeapTupleSetOid(tup, GetNewOid(relation));
-	}
-	else
-	{
-		/* check there is not space for an OID */
-		Assert(!(tup->t_data->t_infomask & HEAP_HASOID));
-	}
-
 	tup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
 	tup->t_data->t_infomask2 &= ~(HEAP2_XACT_MASK);
 	tup->t_data->t_infomask |= HEAP_XMAX_INVALID;
@@ -2995,10 +2969,10 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
  * This should be used rather than using heap_insert directly in most places
  * where we are modifying system catalogs.
  */
-Oid
+void
 simple_heap_insert(Relation relation, HeapTuple tup)
 {
-	return heap_insert(relation, tup, GetCurrentCommandId(true), 0, NULL);
+	heap_insert(relation, tup, GetCurrentCommandId(true), 0, NULL);
 }
 
 /*
@@ -3656,21 +3630,6 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 	/* the new tuple is ready, except for this: */
 	newtup->t_tableOid = RelationGetRelid(relation);
 
-	/* Fill in OID for newtup */
-	if (relation->rd_rel->relhasoids)
-	{
-#ifdef NOT_USED
-		/* this is redundant with an Assert in HeapTupleSetOid */
-		Assert(newtup->t_data->t_infomask & HEAP_HASOID);
-#endif
-		HeapTupleSetOid(newtup, HeapTupleGetOid(&oldtup));
-	}
-	else
-	{
-		/* check there is not space for an OID */
-		Assert(!(newtup->t_data->t_infomask & HEAP_HASOID));
-	}
-
 	/* Determine columns modified by the update. */
 	modified_attrs = HeapDetermineModifiedColumns(relation, interesting_attrs,
 												  &oldtup, newtup);
@@ -4437,13 +4396,12 @@ heap_tuple_attr_equals(TupleDesc tupdesc, int attrnum,
 
 	/*
 	 * Likewise, automatically say "not equal" for any system attribute other
-	 * than OID and tableOID; we cannot expect these to be consistent in a HOT
-	 * chain, or even to be set correctly yet in the new tuple.
+	 * than tableOID; we cannot expect these to be consistent in a HOT chain,
+	 * or even to be set correctly yet in the new tuple.
 	 */
 	if (attrnum < 0)
 	{
-		if (attrnum != ObjectIdAttributeNumber &&
-			attrnum != TableOidAttributeNumber)
+		if (attrnum != TableOidAttributeNumber)
 			return false;
 	}
 
@@ -8123,16 +8081,7 @@ ExtractReplicaIdentity(Relation relation, HeapTuple tp, bool key_changed, bool *
 		int			attno = idx_rel->rd_index->indkey.values[natt];
 
 		if (attno < 0)
-		{
-			/*
-			 * The OID column can appear in an index definition, but that's
-			 * OK, because we always copy the OID if present (see below).
-			 * Other system columns may not.
-			 */
-			if (attno == ObjectIdAttributeNumber)
-				continue;
 			elog(ERROR, "system column in index");
-		}
 		nulls[attno - 1] = false;
 	}
 
@@ -8141,14 +8090,6 @@ ExtractReplicaIdentity(Relation relation, HeapTuple tp, bool key_changed, bool *
 	RelationClose(idx_rel);
 
 	/*
-	 * Always copy oids if the table has them, even if not included in the
-	 * index. The space in the logged tuple is used anyway, so there's little
-	 * point in not including the information.
-	 */
-	if (relation->rd_rel->relhasoids)
-		HeapTupleSetOid(key_tuple, HeapTupleGetOid(tp));
-
-	/*
 	 * If the tuple, which by here only contains indexed columns, still has
 	 * toasted columns, force them to be inlined. This is somewhat unlikely
 	 * since there's limits on the size of indexed columns, so we don't