Why are the performances of these 2 queries so different?

Question

I have a stored proc that searches for products (250,000 rows) using a full text index.

The stored proc takes a parameter that is the full text search condition. This pa

Answer 1

You've introduced an OR condition. In most cases it is simply much faster to check explicitly for NULL and perform one query vs your method.

For instance try this:

IF @Filter IS NULL
 BEGIN
SELECT TOP 100 ID FROM dbo.Products
END
ELSE
BEGIN
SELECT TOP 100 ID FROM dbo.Products
WHERE @Filter CONTAINS(Name, @Filter)
END