Ignoring errors in Trigger - sql-server

Question

I have a stored procedure which is called inside a trigger on Insert/Update/Delete.
The problem is that there is a certain code block inside this SP which is not critical.
Hence I want to ignore any erros arising from this code block.
I inserted this code block inside a TRY CATCH block. But to my surprise I got the following error:
The current transaction cannot be committed and cannot support operations that write to the log file. Roll back the transaction.
Then I tried using SAVE & ROLLBACK TRANSACTION along with TRY CATCH, that too failed with the following error:
The current transaction cannot be committed and cannot be rolled back to a savepoint. Roll back the entire transaction.
My server version is: Microsoft SQL Server 2008 (SP2) - 10.0.4279.0 (X64)
Sample DDL:
IF OBJECT_ID('TestTrigger') IS NOT NULL
DROP TRIGGER TestTrigger
GO
IF OBJECT_ID('TestProcedure') IS NOT NULL
DROP PROCEDURE TestProcedure
GO
IF OBJECT_ID('TestTable') IS NOT NULL
DROP TABLE TestTable
GO
CREATE TABLE TestTable (Data VARCHAR(20))
GO
CREATE PROC TestProcedure
AS
BEGIN
SAVE TRANSACTION Fallback
BEGIN TRY
DECLARE #a INT = 1/0
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION Fallback
END CATCH
END
GO
CREATE TRIGGER TestTrigger
ON TestTable
FOR INSERT, UPDATE, DELETE
AS
BEGIN
EXEC TestProcedure
END
GO
Code to replicate the error:
BEGIN TRANSACTION
INSERT INTO TestTable VALUES('data')
IF ##ERROR > 0
ROLLBACK TRANSACTION
ELSE
COMMIT TRANSACTION
GO

Answer 1

I was going through the same torment, and I just solved it!!!
Just add this single line at the very first step of your TRIGGER and you're going to be fine:
SET XACT_ABORT OFF;
In my case, I'm handling the error feeding a specific table with the batch that caused the error and the error variables from SQL.
Default value for XACT_ABORT is ON, so the entire transaction won't be commited even if you're handling the error inside a TRY CATCH block (just as I'm doing). Setting its value for OFF will cause the transaction to be commited even when an error occurs.
However, I didn't test it when the error is not handled...
For more info:
SET XACT_ABORT (Transact-SQL) | Microsoft Docs

Answer 2

I'd suggest re-architecting this so that you don't poison the original transaction - maybe have the transaction send a service broker message (or just insert relevant data into some form of queue table), so that the "non-critical" part can take place in a completely independent transaction.
E.g. your trigger becomes:
CREATE TRIGGER TestTrigger
ON TestTable
FOR INSERT, UPDATE, DELETE
AS
BEGIN
INSERT INTO QueueTable (Col1,Col2)
SELECT COALESCE(i.Col1,d.Col1),COALESCE(i.Col2,d.Col2) from inserted i,deleted d
END
GO
You shouldn't do anything inside a trigger that might fail, unless you do want to force the transaction that initiated the trigger action to also fail.

Answer 3

This is a very similar question to Why try catch does not suppress exception in trigger
Also see the answer here T-SQL try catch transaction in trigger

Answer 4

I don’t think you can use savepoints inside a trigger. I mean, you can but I googled about it and I saw a few people saying that they don’t work. If you replace your “save transaction” for a begin transaction, it compiles. Of course it is not necessary because you have the outer transaction control and the inner rollback would rollback everything.