Identity columns

This is the SQL standard-conforming variant of PostgreSQL's serial columns. It fixes a few usability issues that serial columns have: - CREATE TABLE / LIKE copies default but refers to same sequence - cannot add/drop serialness with ALTER TABLE - dropping default does not drop sequence - need to grant separate privileges to sequence - other slight weirdnesses because serial is some kind of special macro Reviewed-by: Vitaly Burovoy <vitaly.burovoy@gmail.com>
2025-06-17 17:02:08 +03:00 · 2017-04-06 08:33:16 -04:00
parent 6bad580d9e
commit 3217327053
57 changed files with 2140 additions and 202 deletions
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@ -361,6 +361,11 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
+static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName,
@ -696,6 +701,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			descriptor->attrs[attnum - 1]->atthasdef = true;
 		}
+
+		if (colDef->identity)
+			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
 	}

 	/*
@ -1281,7 +1289,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 		foreach(cell, rels)
 		{
 			Relation	rel = (Relation) lfirst(cell);
-			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel));
+			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
 			ListCell   *seqcell;

 			foreach(seqcell, seqlist)
@ -2078,6 +2086,12 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   get_collation_name(defcollid),
 									   get_collation_name(newcollid))));

+				/*
+				 * Identity is never inherited.  The new column can have an
+				 * identity definition, so we always just take that one.
+				 */
+				def->identity = newdef->identity;
+
 				/* Copy storage parameter */
 				if (def->storage == 0)
 					def->storage = newdef->storage;
@ -3217,6 +3231,9 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
+			case AT_AddIdentity:
+			case AT_DropIdentity:
+			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
 				break;

@ -3447,6 +3464,18 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
+		case AT_AddIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_ADD_CONSTR;
+			break;
+		case AT_DropIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_DROP;
+			break;
+		case AT_SetIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_COL_ATTRS;
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATPrepDropNotNull(rel, recurse, recursing);
@ -3772,6 +3801,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
+		case AT_AddIdentity:
+			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_SetIdentity:
+			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_DropIdentity:
+			address = ATExecDropIdentity(rel, cmd->name, cmd->missing_ok, lockmode);
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			address = ATExecDropNotNull(rel, cmd->name, lockmode);
 			break;
@ -5120,6 +5158,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		elog(ERROR, "cache lookup failed for relation %u", myrelid);
 	relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;

+	/*
+	 * Cannot add identity column if table has children, because identity does
+	 * not inherit.  (Adding column and identity separately will work.)
+	 */
+	if (colDef->identity &&
+		recurse &&
+		find_inheritance_children(myrelid, NoLock) != NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot recursively add identity column to table that has child tables")));
+
 	/* skip if the name already exists and if_not_exists is true */
 	if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
 	{
@ -5172,6 +5221,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attalign = tform->typalign;
 	attribute.attnotnull = colDef->is_not_null;
 	attribute.atthasdef = false;
+	attribute.attidentity = colDef->identity;
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
@ -5539,6 +5589,12 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));

+	if (get_attidentity(RelationGetRelid(rel), attnum))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Check that the attribute is not in a primary key
 	 *
@ -5755,6 +5811,13 @@ ATExecColumnDefault(Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));

+	if (get_attidentity(RelationGetRelid(rel), attnum))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel)),
+				 newDefault ? 0 : errhint("Use ALTER TABLE ... ALTER COLUMN ... DROP IDENTITY instead.")));
+
 	/*
 	 * Remove any old default for the column.  We use RESTRICT here for
 	 * safety, but at present we do not expect anything to depend on the
@ -5789,6 +5852,224 @@ ATExecColumnDefault(Relation rel, const char *colName,
 	return address;
 }

+/*
+ * ALTER TABLE ALTER COLUMN ADD IDENTITY
+ *
+ * Return the address of the affected column.
+ */
+static ObjectAddress
+ATExecAddIdentity(Relation rel, const char *colName,
+				  Node *def, LOCKMODE lockmode)
+{
+	Relation	attrelation;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	ObjectAddress address;
+	ColumnDef  *cdef = castNode(ColumnDef, def);
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	/* Can't alter a system attribute */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	/*
+	 * Creating a column as identity implies NOT NULL, so adding the identity
+	 * to an existing column that is not NOT NULL would create a state that
+	 * cannot be reproduced without contortions.
+	 */
+	if (!attTup->attnotnull)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->attidentity)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is already an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->atthasdef)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = cdef->identity;
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+{
+	ListCell   *option;
+	DefElem	   *generatedEl = NULL;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	foreach(option, castNode(List, def))
+	{
+		DefElem	   *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "generated") == 0)
+		{
+			if (generatedEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			generatedEl = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	/*
+	 * Even if there is nothing to change here, we run all the checks.  There
+	 * will be a subsequent ALTER SEQUENCE that relies on everything being
+	 * there.
+	 */
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (!attTup->attidentity)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (generatedEl)
+	{
+		attTup->attidentity = defGetInt32(generatedEl);
+		CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+		InvokeObjectPostAlterHook(RelationRelationId,
+								  RelationGetRelid(rel),
+								  attTup->attnum);
+		ObjectAddressSubSet(address, RelationRelationId,
+							RelationGetRelid(rel), attnum);
+	}
+
+	heap_freetuple(tuple);
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+	Oid			seqid;
+	ObjectAddress seqaddress;
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (!attTup->attidentity)
+	{
+		if (!missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+							colName, RelationGetRelationName(rel))));
+		else
+		{
+			ereport(NOTICE,
+					(errmsg("column \"%s\" of relation \"%s\" is not an identity column, skipping",
+							colName, RelationGetRelationName(rel))));
+			heap_freetuple(tuple);
+			heap_close(attrelation, RowExclusiveLock);
+			return InvalidObjectAddress;
+		}
+	}
+
+	attTup->attidentity = '\0';
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	/* drop the internal sequence */
+	seqid = getOwnedSequence(RelationGetRelid(rel), attnum);
+	deleteDependencyRecordsForClass(RelationRelationId, seqid,
+									RelationRelationId, DEPENDENCY_INTERNAL);
+	CommandCounterIncrement();
+	seqaddress.classId = RelationRelationId;
+	seqaddress.objectId = seqid;
+	seqaddress.objectSubId = 0;
+	performDeletion(&seqaddress, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
+
+	return address;
+}
+
 /*
 * ALTER TABLE ALTER COLUMN SET STATISTICS
 */
@ -9539,7 +9820,8 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lock
 				Oid			tableId;
 				int32		colId;

-				if (sequenceIsOwned(relationOid, &tableId, &colId))
+				if (sequenceIsOwned(relationOid, DEPENDENCY_AUTO, &tableId, &colId) ||
+					sequenceIsOwned(relationOid, DEPENDENCY_INTERNAL, &tableId, &colId))
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 							 errmsg("cannot change owner of sequence \"%s\"",
@ -9810,7 +10092,7 @@ change_owner_recurse_to_sequences(Oid relationOid, Oid newOwnerId, LOCKMODE lock
 		if (depForm->refobjsubid == 0 ||
 			depForm->classid != RelationRelationId ||
 			depForm->objsubid != 0 ||
-			depForm->deptype != DEPENDENCY_AUTO)
+			!(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
 			continue;

 		/* Use relation_open just in case it's an index */
@ -12115,7 +12397,8 @@ AlterTableNamespace(AlterObjectSchemaStmt *stmt, Oid *oldschema)
 		Oid			tableId;
 		int32		colId;

-		if (sequenceIsOwned(relid, &tableId, &colId))
+		if (sequenceIsOwned(relid, DEPENDENCY_AUTO, &tableId, &colId) ||
+			sequenceIsOwned(relid, DEPENDENCY_INTERNAL, &tableId, &colId))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot move an owned sequence into another schema"),
@ -12298,7 +12581,7 @@ AlterIndexNamespaces(Relation classRel, Relation rel,
 }

 /*
- * Move all SERIAL-column sequences of the specified relation to another
+ * Move all identity and SERIAL-column sequences of the specified relation to another
 * namespace.
 *
 * Note: we assume adequate permission checking was done by the caller,
@ -12342,7 +12625,7 @@ AlterSeqNamespaces(Relation classRel, Relation rel,
 		if (depForm->refobjsubid == 0 ||
 			depForm->classid != RelationRelationId ||
 			depForm->objsubid != 0 ||
-			depForm->deptype != DEPENDENCY_AUTO)
+			!(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
 			continue;

 		/* Use relation_open just in case it's an index */