Posted by Erland Sommarskog on 06/01/05 10:45

jsfromynr (jatinder.singh@clovertechnologies.com) writes:
> Thanks for your answer and time.
> Sorry for the typo error.
> I can be wrong in my assumption buut isn't it that the two queries are
> working in simliar fashion. Both are taking a value(or two) passing it
> to inner corelated query (funtion) and getting the result.

Just because two queries logically are the same, that does not mean that
performance is. There is quite some overhead with calls to saclar user-
defined functions. Also, when you stuff a subquery into a scalar function,
all the optimizer sees is a call, it does not see the contents of rhe
UDF, so it cannot take any shortcuts.

Table-valued functions are different. Particularly inline functions. Table-
valued inline functions are really just macros, and the query text is
pasted into the query, so the optimizer can rearrange as it likes.

As for the estimates you saw in Query Analyzer, they are just estimates, and
I would not pay too much attention on them.


--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinfo/productdoc/2000/books.asp

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