Support for Instead of Trigger On Views in Babelfish

Currently Postgres does not support Instead of Trigger On Views for DML queries. On running such a query on VIEW, query rewriting substitutes view with underlying base table. Added a hook for skipping the substitution for DML query on the VIEW. This change will add support for Instaed of Triggers for DML queries when using Babelfish. Task: BABEL-2170 Signed-off-by: Deepakshi Mittal <[email protected]>
babelfish-for-postgresql · Oct 2, 2023 · df30c57 · df30c57
1 parent dce7212
commit df30c57
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Showing 4 changed files with 13 additions and 11 deletions.
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
@@ -489,12 +489,6 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString,
 								RelationGetRelationName(rel)),
 						 errdetail("Triggers on foreign tables cannot have transition tables.")));
 
-			if (rel->rd_rel->relkind == RELKIND_VIEW)
-				ereport(ERROR,
-						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-						 errmsg("\"%s\" is a view",
-								RelationGetRelationName(rel)),
-						 errdetail("Triggers on views cannot have transition tables.")));
 
 			/*
 			 * We currently don't allow row-level triggers with transition

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
@@ -54,6 +54,7 @@
 #include "jit/jit.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
+#include "parser/parser.h" 
 #include "parser/parsetree.h"
 #include "storage/bufmgr.h"
 #include "storage/lmgr.h"
@@ -1029,23 +1030,23 @@ CheckValidResultRel(ResultRelInfo *resultRelInfo, CmdType operation)
 			switch (operation)
 			{
 				case CMD_INSERT:
-					if (!trigDesc || !trigDesc->trig_insert_instead_row)
+					if (!trigDesc || (!trigDesc->trig_insert_instead_row && (sql_dialect == SQL_DIALECT_TSQL && !trigDesc->trig_insert_instead_statement)))
 						ereport(ERROR,
 								(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 								 errmsg("cannot insert into view \"%s\"",
 										RelationGetRelationName(resultRel)),
 								 errhint("To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule.")));
 					break;
 				case CMD_UPDATE:
-					if (!trigDesc || !trigDesc->trig_update_instead_row)
+					if (!trigDesc || (!trigDesc->trig_update_instead_row && (sql_dialect == SQL_DIALECT_TSQL && !trigDesc->trig_update_instead_statement)))
 						ereport(ERROR,
 								(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 								 errmsg("cannot update view \"%s\"",
 										RelationGetRelationName(resultRel)),
 								 errhint("To enable updating the view, provide an INSTEAD OF UPDATE trigger or an unconditional ON UPDATE DO INSTEAD rule.")));
 					break;
 				case CMD_DELETE:
-					if (!trigDesc || !trigDesc->trig_delete_instead_row)
+					if (!trigDesc || (!trigDesc->trig_delete_instead_row && (sql_dialect == SQL_DIALECT_TSQL && !trigDesc->trig_delete_instead_statement)))
 						ereport(ERROR,
 								(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 								 errmsg("cannot delete from view \"%s\"",

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
@@ -33,6 +33,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/optimizer.h"
 #include "parser/analyze.h"
+#include "parser/parser.h" 
 #include "parser/parse_coerce.h"
 #include "parser/parse_relation.h"
 #include "parser/parsetree.h"
@@ -45,6 +46,7 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
+ViewInsteadStmtTrigger_hook_type ViewInsteadStmtTrigger_hook = NULL;
 
 /* We use a list of these to detect recursion in RewriteQuery */
 typedef struct rewrite_event
@@ -1472,7 +1474,8 @@ rewriteValuesRTE(Query *parsetree, RangeTblEntry *rte, int rti,
 	 */
 	isAutoUpdatableView = false;
 	if (target_relation->rd_rel->relkind == RELKIND_VIEW &&
-		!view_has_instead_trigger(target_relation, CMD_INSERT))
+		(!view_has_instead_trigger(target_relation, CMD_INSERT) &&
+			!(sql_dialect == SQL_DIALECT_TSQL && ViewInsteadStmtTrigger_hook && (ViewInsteadStmtTrigger_hook)(target_relation, CMD_INSERT))))
 	{
 		List	   *locks;
 		bool		hasUpdate;
@@ -3953,7 +3956,8 @@ RewriteQuery(Query *parsetree, List *rewrite_events, int orig_rt_length)
 		 */
 		if (!instead &&
 			rt_entry_relation->rd_rel->relkind == RELKIND_VIEW &&
-			!view_has_instead_trigger(rt_entry_relation, event))
+			(!view_has_instead_trigger(rt_entry_relation, event) 
+			&& !(sql_dialect == SQL_DIALECT_TSQL && ViewInsteadStmtTrigger_hook && (ViewInsteadStmtTrigger_hook)(rt_entry_relation, event))))
 		{
 			/*
 			 * If there were any qualified INSTEAD rules, don't allow the view

diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
@@ -87,6 +87,9 @@ extern PGDLLIMPORT ExecutorCheckPerms_hook_type ExecutorCheckPerms_hook;
 typedef bool (*TriggerRecuresiveCheck_hook_type) (ResultRelInfo *resultRelInfo);
 extern PGDLLIMPORT TriggerRecuresiveCheck_hook_type TriggerRecuresiveCheck_hook;
 
+typedef bool (*ViewInsteadStmtTrigger_hook_type) (Relation view, CmdType event);
+extern PGDLLIMPORT ViewInsteadStmtTrigger_hook_type ViewInsteadStmtTrigger_hook;
+
 typedef bool (*check_rowcount_hook_type) (int es_processed);
 extern PGDLLIMPORT check_rowcount_hook_type check_rowcount_hook;