Move BuildDescForRelation() from tupdesc.c to tablecmds.c

BuildDescForRelation() main job is to convert ColumnDef lists to
pg_attribute/tuple descriptor arrays, which is really mostly an
internal subroutine of DefineRelation() and some related functions,
which is more the remit of tablecmds.c and doesn't have much to do
with the basic tuple descriptor interfaces in tupdesc.c.  This is also
supported by observing the header includes we can remove in tupdesc.c.
By moving it over, we can also (in the future) make
BuildDescForRelation() use more internals of tablecmds.c that are not
sensible to be exposed in tupdesc.c.

Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org

src/backend/access/common/tupdesc.c

@@ -25,9 +25,6 @@
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/hashfn.h"
-#include "miscadmin.h"
-#include "parser/parse_type.h"
-#include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
 #include "utils/resowner_private.h"
@@ -778,109 +775,6 @@ TupleDescInitEntryCollation(TupleDesc desc,
 	TupleDescAttr(desc, attributeNumber - 1)->attcollation = collationid;
 }
 
-
-/*
- * BuildDescForRelation
- *
- * Given a list of ColumnDef nodes, build a TupleDesc.
- *
- * Note: tdtypeid will need to be filled in later on.
- */
-TupleDesc
-BuildDescForRelation(const List *columns)
-{
-	int			natts;
-	AttrNumber	attnum;
-	ListCell   *l;
-	TupleDesc	desc;
-	bool		has_not_null;
-	char	   *attname;
-	Oid			atttypid;
-	int32		atttypmod;
-	Oid			attcollation;
-	int			attdim;
-
-	/*
-	 * allocate a new tuple descriptor
-	 */
-	natts = list_length(columns);
-	desc = CreateTemplateTupleDesc(natts);
-	has_not_null = false;
-
-	attnum = 0;
-
-	foreach(l, columns)
-	{
-		ColumnDef  *entry = lfirst(l);
-		AclResult	aclresult;
-		Form_pg_attribute att;
-
-		/*
-		 * for each entry in the list, get the name and type information from
-		 * the list and have TupleDescInitEntry fill in the attribute
-		 * information we need.
-		 */
-		attnum++;
-
-		attname = entry->colname;
-		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
-
-		aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
-		if (aclresult != ACLCHECK_OK)
-			aclcheck_error_type(aclresult, atttypid);
-
-		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
-		attdim = list_length(entry->typeName->arrayBounds);
-		if (attdim > PG_INT16_MAX)
-			ereport(ERROR,
-					errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-					errmsg("too many array dimensions"));
-
-		if (entry->typeName->setof)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("column \"%s\" cannot be declared SETOF",
-							attname)));
-
-		TupleDescInitEntry(desc, attnum, attname,
-						   atttypid, atttypmod, attdim);
-		att = TupleDescAttr(desc, attnum - 1);
-
-		/* Override TupleDescInitEntry's settings as requested */
-		TupleDescInitEntryCollation(desc, attnum, attcollation);
-		if (entry->storage)
-			att->attstorage = entry->storage;
-
-		/* Fill in additional stuff not handled by TupleDescInitEntry */
-		att->attnotnull = entry->is_not_null;
-		has_not_null |= entry->is_not_null;
-		att->attislocal = entry->is_local;
-		att->attinhcount = entry->inhcount;
-		att->attidentity = entry->identity;
-		att->attgenerated = entry->generated;
-	}
-
-	if (has_not_null)
-	{
-		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
-
-		constr->has_not_null = true;
-		constr->has_generated_stored = false;
-		constr->defval = NULL;
-		constr->missing = NULL;
-		constr->num_defval = 0;
-		constr->check = NULL;
-		constr->num_check = 0;
-		desc->constr = constr;
-	}
-	else
-	{
-		desc->constr = NULL;
-	}
-
-	return desc;
-}
-
 /*
  * BuildDescFromLists
  *
@@ -889,8 +783,7 @@ BuildDescForRelation(const List *columns)
  *
  * No constraints are generated.
  *
- * This is essentially a cut-down version of BuildDescForRelation for use
+ * This is for use with functions returning RECORD.
- * with functions returning RECORD.
  */
 TupleDesc
 BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations)

src/backend/commands/tablecmds.c

@@ -1277,6 +1277,108 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	return address;
 }
 
+/*
+ * BuildDescForRelation
+ *
+ * Given a list of ColumnDef nodes, build a TupleDesc.
+ *
+ * Note: tdtypeid will need to be filled in later on.
+ */
+TupleDesc
+BuildDescForRelation(const List *columns)
+{
+	int			natts;
+	AttrNumber	attnum;
+	ListCell   *l;
+	TupleDesc	desc;
+	bool		has_not_null;
+	char	   *attname;
+	Oid			atttypid;
+	int32		atttypmod;
+	Oid			attcollation;
+	int			attdim;
+
+	/*
+	 * allocate a new tuple descriptor
+	 */
+	natts = list_length(columns);
+	desc = CreateTemplateTupleDesc(natts);
+	has_not_null = false;
+
+	attnum = 0;
+
+	foreach(l, columns)
+	{
+		ColumnDef  *entry = lfirst(l);
+		AclResult	aclresult;
+		Form_pg_attribute att;
+
+		/*
+		 * for each entry in the list, get the name and type information from
+		 * the list and have TupleDescInitEntry fill in the attribute
+		 * information we need.
+		 */
+		attnum++;
+
+		attname = entry->colname;
+		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
+
+		aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error_type(aclresult, atttypid);
+
+		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
+		attdim = list_length(entry->typeName->arrayBounds);
+		if (attdim > PG_INT16_MAX)
+			ereport(ERROR,
+					errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+					errmsg("too many array dimensions"));
+
+		if (entry->typeName->setof)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("column \"%s\" cannot be declared SETOF",
+							attname)));
+
+		TupleDescInitEntry(desc, attnum, attname,
+						   atttypid, atttypmod, attdim);
+		att = TupleDescAttr(desc, attnum - 1);
+
+		/* Override TupleDescInitEntry's settings as requested */
+		TupleDescInitEntryCollation(desc, attnum, attcollation);
+		if (entry->storage)
+			att->attstorage = entry->storage;
+
+		/* Fill in additional stuff not handled by TupleDescInitEntry */
+		att->attnotnull = entry->is_not_null;
+		has_not_null |= entry->is_not_null;
+		att->attislocal = entry->is_local;
+		att->attinhcount = entry->inhcount;
+		att->attidentity = entry->identity;
+		att->attgenerated = entry->generated;
+	}
+
+	if (has_not_null)
+	{
+		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
+
+		constr->has_not_null = true;
+		constr->has_generated_stored = false;
+		constr->defval = NULL;
+		constr->missing = NULL;
+		constr->num_defval = 0;
+		constr->check = NULL;
+		constr->num_check = 0;
+		desc->constr = constr;
+	}
+	else
+	{
+		desc->constr = NULL;
+	}
+
+	return desc;
+}
+
 /*
  * Emit the right error or warning message for a "DROP" command issued on a
  * non-existent relation

src/include/access/tupdesc.h

@@ -147,8 +147,6 @@ extern void TupleDescInitEntryCollation(TupleDesc desc,
 										AttrNumber attributeNumber,
 										Oid collationid);
 
-extern TupleDesc BuildDescForRelation(const List *columns);
-
 extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
 extern Node *TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum);

src/include/commands/tablecmds.h

@@ -27,6 +27,8 @@ struct AlterTableUtilityContext;	/* avoid including tcop/utility.h here */
 extern ObjectAddress DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 									ObjectAddress *typaddress, const char *queryString);
 
+extern TupleDesc BuildDescForRelation(const List *columns);
+
 extern void RemoveRelations(DropStmt *drop);
 
 extern Oid	AlterTableLookupRelation(AlterTableStmt *stmt, LOCKMODE lockmode);