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]>

contrib/babelfishpg_tsql/src/hooks.c

@@ -150,6 +150,7 @@ 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_ViewInsteadStmtTrigger(Relation view, CmdType event);
 
 static bool plsql_TriggerRecursiveCheck(ResultRelInfo *resultRelInfo);
 static bool bbf_check_rowcount_hook(int es_processed);
@@ -201,6 +202,7 @@ 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 ViewInsteadStmtTrigger_hook_type prev_ViewInsteadStmtTrigger = 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;
@@ -314,6 +316,9 @@ InstallExtendedHooks(void)
 	inherit_view_constraints_from_table_hook = preserve_view_constraints_from_base_table;
 	TriggerRecuresiveCheck_hook = plsql_TriggerRecursiveCheck;
 
+	prev_ViewInsteadStmtTrigger = ViewInsteadStmtTrigger_hook;
+	ViewInsteadStmtTrigger_hook = pltsql_ViewInsteadStmtTrigger; 
+
 	prev_detect_numeric_overflow_hook = detect_numeric_overflow_hook;
 	detect_numeric_overflow_hook = pltsql_detect_numeric_overflow;
 
@@ -421,6 +426,7 @@ UninstallExtendedHooks(void)
 	ExecutorEnd_hook = prev_ExecutorEnd;
 	GetNewObjectId_hook = prev_GetNewObjectId_hook;
 	inherit_view_constraints_from_table_hook = prev_inherit_view_constraints_from_table;
+	ViewInsteadStmtTrigger_hook = prev_ViewInsteadStmtTrigger;
 	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;
@@ -699,6 +705,35 @@ plsql_TriggerRecursiveCheck(ResultRelInfo *resultRelInfo)
 	return false;
 }
 
+/**
+ * To allow rewriting view with base table if the view has an instead of trigger at statement level in BBF
+*/
+static bool
+pltsql_ViewInsteadStmtTrigger(Relation view, CmdType event)
+{
+	TriggerDesc *trigDesc = view->trigdesc;
+
+	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;
+}
+
 /*
  * Wrapper function that calls the initilization function.
  * Calls the pre function call hook on the procname 

test/JDBC/expected/BABEL-2170-vu-cleanup.out

@@ -0,0 +1,21 @@
+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 VIEW IF EXISTS babel_2170_vu_employees_view;
+GO
+
+DROP TABLE IF EXISTS babel_2170_vu_employees;
+GO
+
+SELECT name FROM sys.sysobjects WHERE name LIKE 'babel_2170%' ORDER BY name;
+GO
+~~START~~
+varchar
+~~END~~
+

test/JDBC/expected/BABEL-2170-vu-prepare.out

@@ -0,0 +1,31 @@
+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');
+INSERT INTO babel_2170_vu_employees VALUES(3, 'ana', '1st Street', '3000');
+INSERT INTO babel_2170_vu_employees VALUES(4, 'adam', '1st Street', '4000');
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 1~~
+
+~~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

test/JDBC/expected/BABEL-2170-vu-verify.out

@@ -0,0 +1,138 @@
+-- Instead of Insert Trigger on View 
+CREATE TRIGGER babel_2170_vu_employees_view_iot_insert ON babel_2170_vu_employees_view
+INSTEAD OF INSERT
+AS
+BEGIN
+    UPDATE babel_2170_vu_employees SET EmployeeAddress = 'New Street' WHERE EmployeeID = 3;
+END
+GO
+
+INSERT INTO babel_2170_vu_employees_view VALUES(5, 'alex', '1st Street', '5000');
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 1~~
+
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees;
+GO
+~~START~~
+int
+4
+~~END~~
+
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees_view;
+GO
+~~START~~
+int
+4
+~~END~~
+
+
+UPDATE babel_2170_vu_employees SET EmployeeAddress = '1st Street' WHERE EmployeeID = 3;
+GO
+~~ROW COUNT: 1~~
+
+
+-- Instead of Update Trigger on View 
+CREATE TRIGGER babel_2170_vu_employees_view_iot_update ON babel_2170_vu_employees_view
+INSTEAD OF UPDATE
+AS
+BEGIN
+    UPDATE babel_2170_vu_employees SET MonthSalary = MonthSalary + 100 WHERE EmployeeID = 3;
+END
+GO
+
+UPDATE babel_2170_vu_employees_view SET MonthSalary = MonthSalary +1 WHERE EmployeeID = 3;
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 1~~
+
+
+SELECT EmployeeID,EmployeeName, EmployeeAddress, MonthSalary FROM babel_2170_vu_employees WHERE EmployeeID = 3 ORDER BY EmployeeID;
+GO
+~~START~~
+int#!#varchar#!#varchar#!#numeric
+3#!#ana#!#1st Street#!#3100.00
+~~END~~
+
+
+UPDATE babel_2170_vu_employees SET MonthSalary = 3000 WHERE EmployeeID = 3;
+GO
+~~ROW COUNT: 1~~
+
+
+BEGIN TRANSACTION
+    UPDATE babel_2170_vu_employees_view SET MonthSalary = MonthSalary +1 WHERE EmployeeID IN (3, 4);
+COMMIT TRANSACTION;
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 2~~
+
+
+SELECT EmployeeID, EmployeeName, EmployeeAddress, MonthSalary FROM babel_2170_vu_employees WHERE EmployeeID IN (3, 4) ORDER BY EmployeeID;
+GO
+~~START~~
+int#!#varchar#!#varchar#!#numeric
+3#!#ana#!#1st Street#!#3100.00
+4#!#adam#!#1st Street#!#4000.00
+~~END~~
+
+
+UPDATE babel_2170_vu_employees SET MonthSalary = 3000 WHERE EmployeeID = 3;
+GO
+~~ROW COUNT: 1~~
+
+
+-- Instead of Delete Trigger on View
+CREATE TRIGGER babel_2170_vu_employees_view_iot_delete ON babel_2170_vu_employees_view
+INSTEAD OF DELETE
+AS
+BEGIN
+    UPDATE babel_2170_vu_employees SET MonthSalary = MonthSalary + 100 WHERE EmployeeID = 3;
+END
+GO
+
+BEGIN TRANSACTION
+    DELETE FROM babel_2170_vu_employees_view WHERE EmployeeID IN (1, 2);
+COMMIT TRANSACTION;
+GO
+~~ROW COUNT: 1~~
+
+~~ROW COUNT: 2~~
+
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees_view;
+GO
+~~START~~
+int
+4
+~~END~~
+
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees;
+GO
+~~START~~
+int
+4
+~~END~~
+
+
+SELECT EmployeeID, EmployeeName, EmployeeAddress, MonthSalary FROM babel_2170_vu_employees_view ORDER BY EmployeeID;
+GO
+~~START~~
+int#!#varchar#!#varchar#!#numeric
+1#!#amber#!#1st Street#!#1000.00
+2#!#angel#!#1st Street#!#2000.00
+3#!#ana#!#1st Street#!#3100.00
+4#!#adam#!#1st Street#!#4000.00
+~~END~~
+
+
+UPDATE babel_2170_vu_employees SET MonthSalary = 3000 WHERE EmployeeID = 3;
+GO
+~~ROW COUNT: 1~~
+

test/JDBC/input/triggers/BABEL-2170-vu-cleanup.sql

@@ -0,0 +1,17 @@
+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 VIEW IF EXISTS babel_2170_vu_employees_view;
+GO
+
+DROP TABLE IF EXISTS babel_2170_vu_employees;
+GO
+
+SELECT name FROM sys.sysobjects WHERE name LIKE 'babel_2170%' ORDER BY name;
+GO

test/JDBC/input/triggers/BABEL-2170-vu-prepare.sql

@@ -0,0 +1,23 @@
+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');
+INSERT INTO babel_2170_vu_employees VALUES(3, 'ana', '1st Street', '3000');
+INSERT INTO babel_2170_vu_employees VALUES(4, 'adam', '1st Street', '4000');
+GO
+
+CREATE VIEW babel_2170_vu_employees_view AS
+SELECT EmployeeID,
+       EmployeeName,
+       EmployeeAddress,
+       MonthSalary
+FROM babel_2170_vu_employees
+WHERE EmployeeName LIKE 'a%';
+GO

test/JDBC/input/triggers/BABEL-2170-vu-verify.sql

@@ -0,0 +1,75 @@
+-- Instead of Insert Trigger on View 
+CREATE TRIGGER babel_2170_vu_employees_view_iot_insert ON babel_2170_vu_employees_view
+INSTEAD OF INSERT
+AS
+BEGIN
+    UPDATE babel_2170_vu_employees SET EmployeeAddress = 'New Street' WHERE EmployeeID = 3;
+END
+GO
+
+INSERT INTO babel_2170_vu_employees_view VALUES(5, 'alex', '1st Street', '5000');
+GO
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees;
+GO
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees_view;
+GO
+
+UPDATE babel_2170_vu_employees SET EmployeeAddress = '1st Street' WHERE EmployeeID = 3;
+GO
+
+-- Instead of Update Trigger on View 
+CREATE TRIGGER babel_2170_vu_employees_view_iot_update ON babel_2170_vu_employees_view
+INSTEAD OF UPDATE
+AS
+BEGIN
+    UPDATE babel_2170_vu_employees SET MonthSalary = MonthSalary + 100 WHERE EmployeeID = 3;
+END
+GO
+
+UPDATE babel_2170_vu_employees_view SET MonthSalary = MonthSalary +1 WHERE EmployeeID = 3;
+GO
+
+SELECT EmployeeID,EmployeeName, EmployeeAddress, MonthSalary FROM babel_2170_vu_employees WHERE EmployeeID = 3 ORDER BY EmployeeID;
+GO
+
+UPDATE babel_2170_vu_employees SET MonthSalary = 3000 WHERE EmployeeID = 3;
+GO
+
+BEGIN TRANSACTION
+    UPDATE babel_2170_vu_employees_view SET MonthSalary = MonthSalary +1 WHERE EmployeeID IN (3, 4);
+COMMIT TRANSACTION;
+GO
+
+SELECT EmployeeID, EmployeeName, EmployeeAddress, MonthSalary FROM babel_2170_vu_employees WHERE EmployeeID IN (3, 4) ORDER BY EmployeeID;
+GO
+
+UPDATE babel_2170_vu_employees SET MonthSalary = 3000 WHERE EmployeeID = 3;
+GO
+
+-- Instead of Delete Trigger on View
+CREATE TRIGGER babel_2170_vu_employees_view_iot_delete ON babel_2170_vu_employees_view
+INSTEAD OF DELETE
+AS
+BEGIN
+    UPDATE babel_2170_vu_employees SET MonthSalary = MonthSalary + 100 WHERE EmployeeID = 3;
+END
+GO
+
+BEGIN TRANSACTION
+    DELETE FROM babel_2170_vu_employees_view WHERE EmployeeID IN (1, 2);
+COMMIT TRANSACTION;
+GO
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees_view;
+GO
+
+SELECT COUNT(EmployeeID) FROM babel_2170_vu_employees;
+GO
+
+SELECT EmployeeID, EmployeeName, EmployeeAddress, MonthSalary FROM babel_2170_vu_employees_view ORDER BY EmployeeID;
+GO
+
+UPDATE babel_2170_vu_employees SET MonthSalary = 3000 WHERE EmployeeID = 3;
+GO