Performance Tuning TVFs With Optional Parameters

Arvind Shyamsundar walks us through a scenario with user-defined functions with optional parameters:

If you notice carefully, the above query is an example of ‘optional parameters’ wherein the same query caters to situations where there are specific values for the parameters as well as other cases where there are none. Due to the implementation of the query (specifically the usage of ISNULL(@paramname, ColName)) what ends up happening is that the query plan thus generated will not leverage any indexes on the table. While this query can be refactored to separate versions for cases where the parameter values are supplied, and where they are not, another viable option is to use OPTION (RECOMPILE) on the statement level. This is an acceptable solution in most cases because the cost of scanning the table is often far higher than the cost of recompiling this query. So here is how we used OPTION RECOMPILE in this case:

Arvind walks us through three separate solutions.  My fourth solution is, don’t use user-defined table-valued functions.

Related Posts

Testing TPC-H with Batch Mode

Niko Neugebauer looks at TPC-H query testing in both row mode and batch mode: I executed every single query enough times so that the execution would be run totally In-Memory (64GB of RAM is enough because we have our data compressed, as I mentioned earlier in the SETUP part). This would allow me to mimic […]

Read More

Application Caching at Stack Overflow

Nick Craver has a long post on how Stack Overflow does application caching: For everyone who hates caching, this is the section for you! Yes, I’m totally playing both sides. Given the above and how drastic the wins are, why wouldn’t we cache something? Well, because every single decision has trade-offs. Every. Single. One. It could be as […]

Read More

Categories

October 2017
MTWTFSS
« Sep Nov »
 1
2345678
9101112131415
16171819202122
23242526272829
3031