Question

I would like to get some clarification to this answer -> Nested stored procedures containing TRY CATCH ROLLBACK pattern?

Below is the code sample from the above link

 1 CREATE PROCEDURE [Name]
 2 AS
 3 SET XACT_ABORT, NOCOUNT ON
 4
 5 DECLARE @starttrancount int
 6
 7 BEGIN TRY
 8    SELECT @starttrancount = @@TRANCOUNT
 9
10    IF @starttrancount = 0
11        BEGIN TRANSACTION
12
13       [...Perform work, call nested procedures...]
14
15    IF @starttrancount = 0 
16        COMMIT TRANSACTION
17 END TRY
19 BEGIN CATCH
20    IF XACT_STATE() <> 0 AND @starttrancount = 0 
21        ROLLBACK TRANSACTION
22    RAISERROR [rethrow caught error using @ErrorNumber, @ErrorMessage, etc]
23 END CATCH
24 GO

Suppose it is called from the legacy stored procedure that starts a transaction.
In this case this proc will not start transaction of its own, but will alter the XACT_ABORT state for the call.

So, I have a few questions here.

• Is XACT_ABORT active for the current
  proc only, or for the whole call
  stack?
• If I want to refactor a proc to use
  SET XACT_ABORT ON, do I need to pair
  it up with SET XACT_ABORT OFF? Is this the safest way to do it for legacy code?

Below is the modified sample that turns on XACT_ABORT conditionally and pairs it up with turning it off on a proc exit

CREATE PROCEDURE [Name]
AS
SET NOCOUNT ON

DECLARE @starttrancount int

BEGIN TRY
   SELECT @starttrancount = @@TRANCOUNT

   IF @starttrancount = 0
   BEGIN
      SET XACT_ABORT ON
      BEGIN TRANSACTION
   END

      [...Perform work, call nested procedures...]

   IF @starttrancount = 0 
   BEGIN
      COMMIT TRANSACTION
      SET XACT_ABORT OFF
   END
END TRY
BEGIN CATCH
   IF XACT_STATE() <> 0 AND @starttrancount = 0 
   BEGIN
       ROLLBACK TRANSACTION
       SET XACT_ABORT OFF
   END
   RAISERROR [rethrow caught error using @ErrorNumber, @ErrorMessage, etc]
END CATCH
GO

Answer 1

As far as I can see when execution of a child batch ends it restores the previous value of this setting.

SET NOCOUNT ON;

BEGIN TRAN

SELECT CASE
         WHEN 16384 & @@OPTIONS = 16384
           THEN 'XACT_ABORT IS ON'
         ELSE ' XACT_ABORT IS OFF'
       END

CREATE TABLE #T
  (
     C INT
  )

SET XACT_ABORT OFF

INSERT INTO #T
VALUES      (1)

EXEC ('SET XACT_ABORT ON; 
      INSERT INTO #T VALUES(2);
        SELECT CASE
                    WHEN 16384 & @@OPTIONS = 16384
                    THEN ''XACT_ABORT IS ON''
                    ELSE '' XACT_ABORT IS OFF''
                END 
      ')


INSERT INTO #T
VALUES      (1 / 0)

/*If XACT_ABORT was on we would never get here but we do!*/
COMMIT

SELECT *
FROM   #T

DROP TABLE #T

SELECT CASE
         WHEN 16384 & @@OPTIONS = 16384
           THEN 'XACT_ABORT IS ON'
         ELSE ' XACT_ABORT IS OFF'
       END 

Returns

------------------
 XACT_ABORT IS OFF


------------------
XACT_ABORT IS ON

Msg 8134, Level 16, State 1, Line 31
Divide by zero error encountered.
The statement has been terminated.
C
-----------
1
2


------------------
 XACT_ABORT IS OFF