Support Instead of Trigger On Views

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 Instead of Triggers for DML queries when using Babelfish. Task: BABEL-2170/BABEL-4532/BABEL-4514 Signed-off-by: Deepakshi Mittal <[email protected]>
babelfish-for-postgresql · Dec 19, 2023 · fc8ac98 · fc8ac98
1 parent dff6a8f
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diff --git a/contrib/babelfishpg_tsql/src/hooks.c b/contrib/babelfishpg_tsql/src/hooks.c
@@ -159,6 +159,8 @@ static void pltsql_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pltsql_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count, bool execute_once);
 static void pltsql_ExecutorFinish(QueryDesc *queryDesc);
 static void pltsql_ExecutorEnd(QueryDesc *queryDesc);
+static bool pltsql_bbfViewHasInsteadofTrigger(Relation view, CmdType event);
+static bool pltsql_bbfCheckRecursionInTrigger(ResultRelInfo *resultRelInfo);
 
 static bool plsql_TriggerRecursiveCheck(ResultRelInfo *resultRelInfo);
 static bool bbf_check_rowcount_hook(int es_processed);
@@ -210,6 +212,8 @@ static ExecutorFinish_hook_type prev_ExecutorFinish = NULL;
 static ExecutorEnd_hook_type prev_ExecutorEnd = NULL;
 static GetNewObjectId_hook_type prev_GetNewObjectId_hook = NULL;
 static inherit_view_constraints_from_table_hook_type prev_inherit_view_constraints_from_table = NULL;
+static bbfViewHasInsteadofTrigger_hook_type prev_bbfViewHasInsteadofTrigger_hook = NULL;
+static bbfCheckRecursionInTrigger_hook_type prev_bbfCheckRecursionInTrigger_hook = NULL;
 static detect_numeric_overflow_hook_type prev_detect_numeric_overflow_hook = NULL;
 static match_pltsql_func_call_hook_type prev_match_pltsql_func_call_hook = NULL;
 static insert_pltsql_function_defaults_hook_type prev_insert_pltsql_function_defaults_hook = NULL;
@@ -325,6 +329,12 @@ InstallExtendedHooks(void)
 	inherit_view_constraints_from_table_hook = preserve_view_constraints_from_base_table;
 	TriggerRecuresiveCheck_hook = plsql_TriggerRecursiveCheck;
 
+	prev_bbfViewHasInsteadofTrigger_hook = bbfViewHasInsteadofTrigger_hook;
+	bbfViewHasInsteadofTrigger_hook = pltsql_bbfViewHasInsteadofTrigger;
+
+	prev_bbfCheckRecursionInTrigger_hook = bbfCheckRecursionInTrigger_hook;
+	bbfCheckRecursionInTrigger_hook = pltsql_bbfCheckRecursionInTrigger;
+
 	prev_detect_numeric_overflow_hook = detect_numeric_overflow_hook;
 	detect_numeric_overflow_hook = pltsql_detect_numeric_overflow;
 
@@ -440,6 +450,8 @@ UninstallExtendedHooks(void)
 	ExecutorEnd_hook = prev_ExecutorEnd;
 	GetNewObjectId_hook = prev_GetNewObjectId_hook;
 	inherit_view_constraints_from_table_hook = prev_inherit_view_constraints_from_table;
+	bbfViewHasInsteadofTrigger_hook = prev_bbfViewHasInsteadofTrigger_hook;
+	bbfCheckRecursionInTrigger_hook = prev_bbfCheckRecursionInTrigger_hook;
 	detect_numeric_overflow_hook = prev_detect_numeric_overflow_hook;
 	match_pltsql_func_call_hook = prev_match_pltsql_func_call_hook;
 	insert_pltsql_function_defaults_hook = prev_insert_pltsql_function_defaults_hook;
@@ -719,6 +731,84 @@ plsql_TriggerRecursiveCheck(ResultRelInfo *resultRelInfo)
 	return false;
 }
 
+/**
+ * Hook function to skip rewriting VIEW with base table if the VIEW has an instead of trigger
+ * Checks if view have an INSTEAD OF trigger at statement level
+ * If it does, we don't want to treat it as auto-updatable. 
+ * Reference - src/backend/rewrite/rewriteHandler.c view_has_instead_trigger
+*/
+static bool
+pltsql_bbfViewHasInsteadofTrigger(Relation view, CmdType event)
+{
+	TriggerDesc *trigDesc = view->trigdesc;
+	if (trigDesc && triggerOids)
+	{
+		int i;
+		for (i = 0; i < trigDesc->numtriggers; i++)
+		{
+			Trigger *trigger = &trigDesc->triggers[i];
+			Oid current_tgoid = trigger->tgoid;
+			Oid prev_tgoid = InvalidOid;
+			prev_tgoid = lfirst_oid(list_tail(triggerOids));
+			if (prev_tgoid == current_tgoid)
+			{
+				return false; /** Direct recursive trigger case*/
+			}
+			else if (list_member_oid(triggerOids, current_tgoid))
+            {
+                /** Indirect recursive trigger case*/
+                ereport(ERROR,
+                        (errcode(ERRCODE_SYNTAX_ERROR),
+                         errmsg("Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32)")));
+            }
+		}
+	}
+
+	switch (event)
+	{
+		case CMD_INSERT:
+			if(trigDesc && trigDesc->trig_insert_instead_statement)
+				return true;
+			break;
+		case CMD_UPDATE:
+			if (trigDesc && trigDesc->trig_update_instead_statement)
+				return true;
+			break;
+		case CMD_DELETE:
+			if (trigDesc && trigDesc->trig_delete_instead_statement)
+				return true;
+			break;
+		default:
+			elog(ERROR, "unrecognized CmdType: %d", (int) event);
+			break;
+	}
+	return false;
+}
+
+static bool pltsql_bbfCheckRecursionInTrigger(ResultRelInfo *relinfo)
+{
+	if (triggerOids && relinfo->ri_TrigDesc)
+	{
+		TriggerDesc *trigDesc;
+		int i;
+		trigDesc = relinfo->ri_TrigDesc;
+		for (i = 0; i < trigDesc->numtriggers; i++)
+		{
+			Trigger *trigger = &trigDesc->triggers[i];
+			Oid current_tgoid = trigger->tgoid;
+			Oid prev_tgoid = lfirst_oid(list_tail(triggerOids));
+			if (prev_tgoid != current_tgoid && list_member_oid(triggerOids, current_tgoid))
+			{
+				/** Recursive trigger case*/
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						errmsg("Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32)")));
+			}
+		}
+	}
+	return true;
+}
+
 /*
  * Wrapper function that calls the initilization function.
  * Calls the pre function call hook on the procname 

diff --git a/test/JDBC/expected/BABEL-2170-vu-cleanup.out b/test/JDBC/expected/BABEL-2170-vu-cleanup.out
@@ -0,0 +1,39 @@
+-- clean all objects in first database
+USE db1_BABEL2170;
+GO
+
+DROP TRIGGER IF EXISTS babel_2170_vu_employees_view_iot_insert;
+GO
+
+DROP TRIGGER IF EXISTS babel_2170_vu_employees_view_iot_update;
+GO
+
+DROP TRIGGER IF EXISTS babel_2170_vu_employees_view_iot_delete;
+GO
+
+DROP TRIGGER IF EXISTS babel_2170_vu_employees_view_iot_bulkinsert;
+GO
+
+DROP VIEW IF EXISTS babel_2170_vu_employees_view;
+GO
+
+DROP VIEW IF EXISTS babel_2170_vu_employees_view_bulkinsert;
+GO
+
+DROP VIEW IF EXISTS babel_2170_vu_employees_view_2;
+GO
+
+DROP TABLE IF EXISTS babel_2170_vu_employees;
+GO
+
+DROP VIEW IF EXISTS babel_2170_vu_employees_view_txn;
+GO
+
+DROP TABLE IF EXISTS babel_2170_vu_employees_txn;
+GO
+
+USE MASTER; 
+GO
+
+DROP DATABASE IF EXISTS db1_BABEL2170;
+GO
diff --git a/test/JDBC/expected/BABEL-2170-vu-prepare.out b/test/JDBC/expected/BABEL-2170-vu-prepare.out
@@ -0,0 +1,105 @@
+-- We will create two databases db1_BABEL2170, db2_BABEL2170
+CREATE DATABASE db1_BABEL2170;
+GO
+
+USE db1_BABEL2170;
+GO
+
+CREATE TABLE babel_2170_vu_employees
+(
+    EmployeeID      int NOT NULL,
+    EmployeeName    VARCHAR(50),
+    EmployeeAddress VARCHAR(50),
+    MonthSalary     NUMERIC(10, 2)
+)
+GO
+
+INSERT INTO babel_2170_vu_employees VALUES(1, 'amber', '1st Street', '1000');
+INSERT INTO babel_2170_vu_employees VALUES(2, 'angel', '1st Street', '2000');
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 1~~
+
+
+CREATE VIEW babel_2170_vu_employees_view AS
+SELECT EmployeeID,
+       EmployeeName,
+       EmployeeAddress,
+       MonthSalary
+FROM babel_2170_vu_employees
+WHERE EmployeeName LIKE 'a%';
+GO
+
+CREATE VIEW babel_2170_vu_employees_view_bulkinsert AS
+SELECT EmployeeID,
+       EmployeeName,
+       EmployeeAddress,
+       MonthSalary
+FROM babel_2170_vu_employees
+WHERE EmployeeName LIKE 'b%';
+GO
+
+CREATE VIEW babel_2170_vu_employees_view_2 AS
+SELECT EmployeeID,
+       EmployeeName,
+       EmployeeAddress,
+       MonthSalary
+FROM babel_2170_vu_employees
+WHERE EmployeeName LIKE 'a%';
+GO
+
+CREATE SCHEMA schema_2170;
+GO
+
+CREATE TABLE schema_2170.babel_2170_vu_employees
+(
+    EmployeeID      int NOT NULL,
+    EmployeeName    VARCHAR(50),
+    EmployeeAddress VARCHAR(50),
+    MonthSalary     NUMERIC(10, 2)
+)
+GO
+
+INSERT INTO schema_2170.babel_2170_vu_employees VALUES(1, 'amber', '1st Street', '1000');
+INSERT INTO schema_2170.babel_2170_vu_employees VALUES(2, 'angel', '1st Street', '2000');
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 1~~
+
+
+CREATE VIEW schema_2170.babel_2170_vu_employees_view AS
+SELECT EmployeeID,
+       EmployeeName,
+       EmployeeAddress,
+       MonthSalary
+FROM schema_2170.babel_2170_vu_employees
+WHERE EmployeeName LIKE 'a%';
+GO
+
+CREATE TABLE babel_2170_vu_employees_txn
+(
+    EmployeeID      int NOT NULL,
+    EmployeeName    VARCHAR(50),
+    EmployeeAddress VARCHAR(50),
+    MonthSalary     NUMERIC(10, 2)
+)
+GO
+
+INSERT INTO babel_2170_vu_employees_txn VALUES(1, 'amber', '1st Street', '1000');
+INSERT INTO babel_2170_vu_employees_txn VALUES(2, 'angel', '1st Street', '2000');
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 1~~
+
+
+CREATE VIEW babel_2170_vu_employees_view_txn AS
+SELECT EmployeeID,
+       EmployeeName,
+       EmployeeAddress,
+       MonthSalary
+FROM babel_2170_vu_employees_txn
+WHERE EmployeeName LIKE 'a%';
+GO