Sunday, March 11, 2012

Compare Queries

Chris,
Put both queries in the same query window and run them. Then the
percentiles will reflect both queries. Therefore, if query1 and its
functions use 25% and query2 and its functions use 75%, that suggests that
query1 is more efficient. However, UDFs (and some other functions) do
degrade the reliability of these numbers. Still, it is a good first take.
However, running both queries repeatly and getting a set of actual execution
times for each will, in the final analysis, be a more accurate measure of
the queries.
RLF
"Chris" <nospam@.nospam.com> wrote in message
news:emgxeRbuHHA.3796@.TK2MSFTNGP02.phx.gbl...
>I am creating an SP. I want to compare alternative ways of writing the
>query to see which one is the most efficient. I am trying to use the
>execution plan but it doesn't give an overall cost of the query so I can
>compare it to the alternative query. Rather I get a break down of the
>various steps (this query uses functions which produce aggregates and these
>steps are included in the execution plan) . I want to explore the steps
>later, at this point I just want to compare the two queries as a whole.
>What is the best way of going about this? Regards, Chris.
>
On Jun 29, 1:02 am, "Chris" <nos...@.nospam.com> wrote:
> The wording is a bit unclear. My SP could potentially contain a variety of
> variables obtained from sub queries etc. This means there will be more than
> just two queries to compare. How would you deal with a more complex scenario
> with SP's that use temp tables or subqueries etc.
> Regards, Chris.
> "Russell Fields" <russellfie...@.nomail.com> wrote in message
> news:emDSzebuHHA.4916@.TK2MSFTNGP04.phx.gbl...
>
>
>
>
> - Show quoted text -
Make each version of your SP. Then capture in profiler
SP:StatementCompleted
with read,writes,duration,CPU
You need to clear database and procedure cache before each
execution of SP to have accurate values
DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE

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