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

4 files changed, 34 insertions, 56 deletions

diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index ccb69bdd616..06dd628a5bc 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -384,7 +384,6 @@ heap_attisnull(HeapTuple tup, int attnum, TupleDesc tupleDesc)
 	{
 		case TableOidAttributeNumber:
 		case SelfItemPointerAttributeNumber:
-		case ObjectIdAttributeNumber:
 		case MinTransactionIdAttributeNumber:
 		case MinCommandIdAttributeNumber:
 		case MaxTransactionIdAttributeNumber:
@@ -642,9 +641,6 @@ heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
 			/* pass-by-reference datatype */
 			result = PointerGetDatum(&(tup->t_self));
 			break;
-		case ObjectIdAttributeNumber:
-			result = ObjectIdGetDatum(HeapTupleGetOid(tup));
-			break;
 		case MinTransactionIdAttributeNumber:
 			result = TransactionIdGetDatum(HeapTupleHeaderGetRawXmin(tup->t_data));
 			break;
@@ -839,9 +835,6 @@ expand_tuple(HeapTuple *targetHeapTuple,
 	else
 		targetNullLen = 0;
 
-	if (tupleDesc->tdhasoid)
-		len += sizeof(Oid);
-
 	/*
 	 * Allocate and zero the space needed.  Note that the tuple body and
 	 * HeapTupleData management structure are allocated in one chunk.
@@ -1065,9 +1058,6 @@ heap_form_tuple(TupleDesc tupleDescriptor,
 	if (hasnull)
 		len += BITMAPLEN(numberOfAttributes);
 
-	if (tupleDescriptor->tdhasoid)
-		len += sizeof(Oid);
-
 	hoff = len = MAXALIGN(len); /* align user data safely */
 
 	data_len = heap_compute_data_size(tupleDescriptor, values, isnull);
@@ -1099,9 +1089,6 @@ heap_form_tuple(TupleDesc tupleDescriptor,
 	HeapTupleHeaderSetNatts(td, numberOfAttributes);
 	td->t_hoff = hoff;
 
-	if (tupleDescriptor->tdhasoid)	/* else leave infomask = 0 */
-		td->t_infomask = HEAP_HASOID;
-
 	heap_fill_tuple(tupleDescriptor,
 					values,
 					isnull,
@@ -1171,14 +1158,11 @@ heap_modify_tuple(HeapTuple tuple,
 	pfree(isnull);
 
 	/*
-	 * copy the identification info of the old tuple: t_ctid, t_self, and OID
-	 * (if any)
+	 * copy the identification info of the old tuple: t_ctid, t_self
 	 */
 	newTuple->t_data->t_ctid = tuple->t_data->t_ctid;
 	newTuple->t_self = tuple->t_self;
 	newTuple->t_tableOid = tuple->t_tableOid;
-	if (tupleDesc->tdhasoid)
-		HeapTupleSetOid(newTuple, HeapTupleGetOid(tuple));
 
 	return newTuple;
 }
@@ -1237,14 +1221,11 @@ heap_modify_tuple_by_cols(HeapTuple tuple,
 	pfree(isnull);
 
 	/*
-	 * copy the identification info of the old tuple: t_ctid, t_self, and OID
-	 * (if any)
+	 * copy the identification info of the old tuple: t_ctid, t_self
 	 */
 	newTuple->t_data->t_ctid = tuple->t_data->t_ctid;
 	newTuple->t_self = tuple->t_self;
 	newTuple->t_tableOid = tuple->t_tableOid;
-	if (tupleDesc->tdhasoid)
-		HeapTupleSetOid(newTuple, HeapTupleGetOid(tuple));
 
 	return newTuple;
 }
@@ -1412,9 +1393,6 @@ heap_form_minimal_tuple(TupleDesc tupleDescriptor,
 	if (hasnull)
 		len += BITMAPLEN(numberOfAttributes);
 
-	if (tupleDescriptor->tdhasoid)
-		len += sizeof(Oid);
-
 	hoff = len = MAXALIGN(len); /* align user data safely */
 
 	data_len = heap_compute_data_size(tupleDescriptor, values, isnull);
@@ -1433,9 +1411,6 @@ heap_form_minimal_tuple(TupleDesc tupleDescriptor,
 	HeapTupleHeaderSetNatts(tuple, numberOfAttributes);
 	tuple->t_hoff = hoff + MINIMAL_TUPLE_OFFSET;
 
-	if (tupleDescriptor->tdhasoid)	/* else leave infomask = 0 */
-		tuple->t_infomask = HEAP_HASOID;
-
 	heap_fill_tuple(tupleDescriptor,
 					values,
 					isnull,
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index db84da06789..eece89aa21f 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -757,8 +757,8 @@ add_string_reloption(bits32 kinds, const char *name, const char *desc, const cha
  * reloptions value (possibly NULL), and we replace or remove entries
  * as needed.
  *
- * If ignoreOids is true, then we should ignore any occurrence of "oids"
- * in the list (it will be or has been handled by interpretOidsOption()).
+ * If acceptOidsOff is true, then we allow oids = false, but throw error when
+ * on. This is solely needed for backwards compatibility.
  *
  * Note that this is not responsible for determining whether the options
  * are valid, but it does check that namespaces for all the options given are
@@ -771,7 +771,7 @@ add_string_reloption(bits32 kinds, const char *name, const char *desc, const cha
  */
 Datum
 transformRelOptions(Datum oldOptions, List *defList, const char *namspace,
-					char *validnsps[], bool ignoreOids, bool isReset)
+					char *validnsps[], bool acceptOidsOff, bool isReset)
 {
 	Datum		result;
 	ArrayBuildState *astate;
@@ -882,9 +882,6 @@ transformRelOptions(Datum oldOptions, List *defList, const char *namspace,
 									def->defnamespace)));
 			}
 
-			if (ignoreOids && strcmp(def->defname, "oids") == 0)
-				continue;
-
 			/* ignore if not in the same namespace */
 			if (namspace == NULL)
 			{
@@ -905,6 +902,24 @@ transformRelOptions(Datum oldOptions, List *defList, const char *namspace,
 				value = defGetString(def);
 			else
 				value = "true";
+
+			/*
+			 * This is not a great place for this test, but there's no other
+			 * convenient place to filter the option out. As WITH (oids =
+			 * false) will be removed someday, this seems like an acceptable
+			 * amount of ugly.
+			 */
+			if (acceptOidsOff && def->defnamespace == NULL &&
+				strcmp(def->defname, "oids") == 0)
+			{
+				if (defGetBoolean(def))
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("tables declared WITH OIDS are not supported")));
+				/* skip over option, reloptions machinery doesn't know it */
+				continue;
+			}
+
 			len = VARHDRSZ + strlen(def->defname) + 1 + strlen(value);
 			/* +1 leaves room for sprintf's trailing null */
 			t = (text *) palloc(len + 1);
diff --git a/src/backend/access/common/tupconvert.c b/src/backend/access/common/tupconvert.c
index 21fe8ae4909..fc88aa376ac 100644
--- a/src/backend/access/common/tupconvert.c
+++ b/src/backend/access/common/tupconvert.c
@@ -138,13 +138,9 @@ convert_tuples_by_position(TupleDesc indesc,
 
 	/*
 	 * Check to see if the map is one-to-one, in which case we need not do a
-	 * tuple conversion.  We must also insist that both tupdescs either
-	 * specify or don't specify an OID column, else we need a conversion to
-	 * add/remove space for that.  (For some callers, presence or absence of
-	 * an OID column perhaps would not really matter, but let's be safe.)
+	 * tuple conversion.
 	 */
-	if (indesc->natts == outdesc->natts &&
-		indesc->tdhasoid == outdesc->tdhasoid)
+	if (indesc->natts == outdesc->natts)
 	{
 		for (i = 0; i < n; i++)
 		{
@@ -344,13 +340,9 @@ convert_tuples_by_name_map_if_req(TupleDesc indesc,
 
 	/*
 	 * Check to see if the map is one-to-one, in which case we need not do a
-	 * tuple conversion.  We must also insist that both tupdescs either
-	 * specify or don't specify an OID column, else we need a conversion to
-	 * add/remove space for that.  (For some callers, presence or absence of
-	 * an OID column perhaps would not really matter, but let's be safe.)
+	 * tuple conversion.
 	 */
-	if (indesc->natts == outdesc->natts &&
-		indesc->tdhasoid == outdesc->tdhasoid)
+	if (indesc->natts == outdesc->natts)
 	{
 		same = true;
 		for (i = 0; i < n; i++)
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index b0434b46720..5354a04639b 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -42,7 +42,7 @@
  * caller can overwrite this if needed.
  */
 TupleDesc
-CreateTemplateTupleDesc(int natts, bool hasoid)
+CreateTemplateTupleDesc(int natts)
 {
 	TupleDesc	desc;
 
@@ -73,7 +73,6 @@ CreateTemplateTupleDesc(int natts, bool hasoid)
 	desc->constr = NULL;
 	desc->tdtypeid = RECORDOID;
 	desc->tdtypmod = -1;
-	desc->tdhasoid = hasoid;
 	desc->tdrefcount = -1;		/* assume not reference-counted */
 
 	return desc;
@@ -88,12 +87,12 @@ CreateTemplateTupleDesc(int natts, bool hasoid)
  * caller can overwrite this if needed.
  */
 TupleDesc
-CreateTupleDesc(int natts, bool hasoid, Form_pg_attribute *attrs)
+CreateTupleDesc(int natts, Form_pg_attribute *attrs)
 {
 	TupleDesc	desc;
 	int			i;
 
-	desc = CreateTemplateTupleDesc(natts, hasoid);
+	desc = CreateTemplateTupleDesc(natts);
 
 	for (i = 0; i < natts; ++i)
 		memcpy(TupleDescAttr(desc, i), attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
@@ -114,7 +113,7 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 	TupleDesc	desc;
 	int			i;
 
-	desc = CreateTemplateTupleDesc(tupdesc->natts, tupdesc->tdhasoid);
+	desc = CreateTemplateTupleDesc(tupdesc->natts);
 
 	/* Flat-copy the attribute array */
 	memcpy(TupleDescAttr(desc, 0),
@@ -154,7 +153,7 @@ CreateTupleDescCopyConstr(TupleDesc tupdesc)
 	TupleConstr *constr = tupdesc->constr;
 	int			i;
 
-	desc = CreateTemplateTupleDesc(tupdesc->natts, tupdesc->tdhasoid);
+	desc = CreateTemplateTupleDesc(tupdesc->natts);
 
 	/* Flat-copy the attribute array */
 	memcpy(TupleDescAttr(desc, 0),
@@ -416,8 +415,6 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 		return false;
 	if (tupdesc1->tdtypeid != tupdesc2->tdtypeid)
 		return false;
-	if (tupdesc1->tdhasoid != tupdesc2->tdhasoid)
-		return false;
 
 	for (i = 0; i < tupdesc1->natts; i++)
 	{
@@ -574,7 +571,6 @@ hashTupleDesc(TupleDesc desc)
 
 	s = hash_combine(0, hash_uint32(desc->natts));
 	s = hash_combine(s, hash_uint32(desc->tdtypeid));
-	s = hash_combine(s, hash_uint32(desc->tdhasoid));
 	for (i = 0; i < desc->natts; ++i)
 		s = hash_combine(s, hash_uint32(TupleDescAttr(desc, i)->atttypid));
 
@@ -800,7 +796,7 @@ BuildDescForRelation(List *schema)
 	 * allocate a new tuple descriptor
 	 */
 	natts = list_length(schema);
-	desc = CreateTemplateTupleDesc(natts, false);
+	desc = CreateTemplateTupleDesc(natts);
 	has_not_null = false;
 
 	attnum = 0;
@@ -900,7 +896,7 @@ BuildDescFromLists(List *names, List *types, List *typmods, List *collations)
 	/*
 	 * allocate a new tuple descriptor
 	 */
-	desc = CreateTemplateTupleDesc(natts, false);
+	desc = CreateTemplateTupleDesc(natts);
 
 	attnum = 0;