Creating Unique URI Slugs - is this a Recursive Trigger? (SQL Server)

Question

Here's my table:

dbo.Posts

• PostId (IDENTITY, PK)
• Subject
• UniqueUri (NVARCHAR(350), NOT NULL)

When i create a "Post", i insert a blank UniqueUri (using the NEWID() built-in function).

I then have a trigger on the "Post" table:

CREATE TRIGGER [dbo].[OnAfterInsertUpdatePostTrigger]
   ON  [dbo].[Posts]
   AFTER INSERT, UPDATE
AS 
BEGIN
    SET NOCOUNT ON

    DECLARE @PostIds IdentityType

    INSERT INTO @PostIds
    SELECT PostId
    FROM INSERTED

    -- Create the UniqueUri's.
    EXECUTE [dbo].[UpdatePostsCleanedUriUniqueUri] @PostIds

END

Which calls a SPROC to create the Unique Uri's.

The SPROC has some code like this:

UPDATE a
    SET a.CleanedUri = NEWID(),
        a.UniqueUri = NEWID()
    FROM [dbo].[Posts] a
        INNER JOIN @PostIds b ON a.PostId = b.Id

I noticed when i tried to insert only a single post, it was taking over a minute.

I can only deduce this is a recursive trigger call?

Basically, when a Post is created/updated, i need to create unique uri's (much like stack, for questions).

The only solution i can think of is created another table called UniqueUri's, which would have nothing but the PostId FK and the Uri, e.g a 1-1, which i always try to avoid.

Then the SPROC would update that table.

Any other suggestions/ideas?

Answer 1

One solution to prevent the trigger recursively firing is to eliminate changes to your columns from the trigger:

IF ( NOT UPDATE (CleanedUri) AND NOT UPDATE (UniqueUri ) )
BEGIN
    DECLARE @PostIds IdentityType      
    INSERT INTO @PostIds     
    SELECT PostId     
    FROM INSERTED      

    -- Create the UniqueUri's.     
    EXECUTE [dbo].[UpdatePostsCleanedUriUniqueUri] @PostIds 
END;