Support for weak binding views to allow dropping of underlying objects

contrib/babelfishpg_tsql/runtime/functions.c

@@ -4481,8 +4481,14 @@ objectproperty_internal(PG_FUNCTION_ARGS)
 		 */
 		if (pg_strcasecmp(property, "isschemabound") == 0)
 		{
+			bool is_weak_view = false;
+			bool is_view = (type == OBJECT_TYPE_VIEW);
+
+			if (is_view)
+				check_is_tsql_view(object_id, &is_weak_view);
+
 			pfree(property);
-			PG_RETURN_INT32(0);
+			PG_RETURN_INT32(is_view ? ((int) !is_weak_view) : 0);
 		}
 		/*
 		 * For ExecIsQuotedIdentOn and ExecIsAnsiNullsOn, we hardcoded it to 1

contrib/babelfishpg_tsql/src/catalog.c

@@ -1199,17 +1199,40 @@ get_bbf_view_def_idx_oid()
 }
 
 HeapTuple
-search_bbf_view_def(Relation bbf_view_def_rel, int16 dbid, const char *logical_schema_name, const char *view_name)
+search_bbf_view_def(Relation bbf_view_def_rel, Oid viewOid)
 {
 
 	ScanKeyData scanKey[3];
 	SysScanDesc scan;
 	HeapTuple	scantup,
 				oldtup;
+	Oid 		schema_id;
+	char 		*schema_name = NULL;
+	char		*view_name = NULL;
+	const char  *logical_schema_name = NULL;
+	int16 		dbid = InvalidDbid;
 
-	if (!DbidIsValid(dbid) || logical_schema_name == NULL || view_name == NULL)
+	if (!OidIsValid(viewOid))
 		return NULL;
 
+	schema_id = get_rel_namespace(viewOid);
+	schema_name = get_namespace_name(schema_id);
+	view_name = get_rel_name(viewOid);
+
+	if (!schema_name)
+		return NULL;
+
+	logical_schema_name = get_logical_schema_name(schema_name, true);
+	dbid = get_dbid_from_physical_schema_name(schema_name, true);
+
+	if (!DbidIsValid(dbid) || logical_schema_name == NULL || view_name == NULL)
+	{
+		pfree(view_name);
+		pfree(schema_name);
+		if (logical_schema_name)
+			pfree((char *) logical_schema_name);
+		return NULL;
+	}
 
 	/* Search and drop the definition */
 	ScanKeyInit(&scanKey[0],
@@ -1239,7 +1262,7 @@ search_bbf_view_def(Relation bbf_view_def_rel, int16 dbid, const char *logical_s
 
 /* Checks if it is view created during v2.2.0 or after that */
 bool
-check_is_tsql_view(Oid relid)
+check_is_tsql_view(Oid relid, bool *is_weak_view)
 {
 	Oid			schema_oid;
 	Relation	bbf_view_def_rel;
@@ -1249,10 +1272,17 @@ check_is_tsql_view(Oid relid)
 	int16		logical_dbid;
 	const char *logical_schema_name;
 	bool		is_tsql_view = false;
+	bool 		bisnull;
+	Datum 		flag_values_datum;
+	uint64 		flag_values;
 
 	view_name = get_rel_name(relid);
 	schema_oid = get_rel_namespace(relid);
 	schema_name = get_namespace_name(schema_oid);
+
+	if (is_weak_view != NULL)
+		*is_weak_view = false;
+
 	if (view_name == NULL || schema_name == NULL || is_shared_schema(schema_name))
 	{
 		if (view_name)
@@ -1273,12 +1303,27 @@ check_is_tsql_view(Oid relid)
 	}
 	/* Fetch the relation */
 	bbf_view_def_rel = table_open(get_bbf_view_def_oid(), AccessShareLock);
-
-	scantup = search_bbf_view_def(bbf_view_def_rel, logical_dbid, logical_schema_name, view_name);
+	scantup = search_bbf_view_def(bbf_view_def_rel, relid);
 
 	if (HeapTupleIsValid(scantup))
 	{
 		is_tsql_view = true;
+
+		/* Check if the view is a weak bound view */
+		if (is_weak_view != NULL)
+		{
+			flag_values_datum = heap_getattr(scantup, 
+								Anum_bbf_view_def_flag_values,
+								RelationGetDescr(bbf_view_def_rel), 
+								&bisnull);
+
+			if (!bisnull)
+			{
+				flag_values = DatumGetUInt64(flag_values_datum);
+				*is_weak_view = (flag_values & BBF_VIEW_DEF_FLAG_IS_WEAK_VIEW) != 0;
+			}
+		}
+
 		heap_freetuple(scantup);
 	}
 	table_close(bbf_view_def_rel, AccessShareLock);

contrib/babelfishpg_tsql/src/catalog.h

@@ -202,18 +202,22 @@ typedef FormData_authid_user_ext *Form_authid_user_ext;
 #define Anum_bbf_view_def_schema_name 2
 #define Anum_bbf_view_def_object_name 3
 #define Anum_bbf_view_def_definition 4
+#define Anum_bbf_view_def_flag_validity 5
+#define Anum_bbf_view_def_flag_values 6
 #define BBF_VIEW_DEF_NUM_COLS 8
 #define BBF_VIEW_DEF_FLAG_IS_ANSI_NULLS_ON (1<<0)
 #define BBF_VIEW_DEF_FLAG_USES_QUOTED_IDENTIFIER (1<<1)
 #define BBF_VIEW_DEF_FLAG_CREATED_IN_OR_AFTER_2_4 (0<<2)
+#define BBF_VIEW_DEF_FLAG_IS_WEAK_VIEW (1<<3)
+#define BBF_VIEW_DEF_FLAG_IS_BROKEN (1<<4)
+
 extern Oid	bbf_view_def_oid;
 extern Oid	bbf_view_def_idx_oid;
 
 extern Oid	get_bbf_view_def_oid(void);
 extern Oid	get_bbf_view_def_idx_oid(void);
-extern HeapTuple search_bbf_view_def(Relation bbf_view_def_rel, int16 dbid,
-									 const char *logical_schema_name, const char *view_name);
-extern bool check_is_tsql_view(Oid relid);
+extern HeapTuple search_bbf_view_def(Relation bbf_view_def_rel, Oid viewOid);
+extern bool check_is_tsql_view(Oid relid, bool *is_weak_view);
 extern void clean_up_bbf_view_def(int16 dbid);
 extern void drop_bbf_schema_permission_entries(int16 dbid);
 

contrib/babelfishpg_tsql/src/guc.c

@@ -18,6 +18,7 @@
 #define PLTSQL_DEFAULT_LANGUAGE "us_english"
 
 static int	migration_mode = SINGLE_DB;
+bool		pltsql_weak_view_binding = false;
 bool		enable_ownership_structure = false;
 
 bool		enable_metadata_inconsistency_check = true;
@@ -630,6 +631,16 @@ define_custom_variables(void)
 							 GUC_NO_RESET_ALL,
 							 NULL, NULL, NULL);
 
+	DefineCustomBoolVariable("babelfishpg_tsql.weak_view_binding",
+							 gettext_noop("Sets the default binding mode for views."),
+							 gettext_noop("When set to false (default), views will bind to the schema of its underlying tables or other objects" 
+										  "When set to true, views created will have weak binding and are no longer bound to schema of its underlying" 
+										  "objects unless explicitly declared in create/alter DDL"),
+							 &pltsql_weak_view_binding,
+							 false,  /* Default is strong binding (false) */
+							 PGC_USERSET,
+							 GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_DISALLOW_IN_AUTO_FILE,
+							 NULL, NULL, NULL);
 
 	/* ANTLR parser */
 	DefineCustomBoolVariable("babelfishpg_tsql.dump_antlr_query_graph",

contrib/babelfishpg_tsql/src/guc.h

@@ -20,6 +20,7 @@ extern bool pltsql_enable_create_alter_view_from_pg;
 extern bool pltsql_enable_linked_servers;
 extern bool pltsql_allow_windows_login;
 extern bool pltsql_allow_fulltext_parser;
+extern bool pltsql_weak_view_binding;
 extern char *pltsql_psql_logical_babelfish_db_name;
 extern int  pltsql_isolation_level_repeatable_read;
 extern int  pltsql_isolation_level_serializable;