Comments on: Is it a good idea to use lambda expressions for querying SharePoint data?

By: Waldek Mastykarz

Waldek Mastykarz — Thu, 05 Jan 2012 06:05:35 +0000

@tareq: Sorry, but I don't really understand what you are trying to achieve. Could you explain it a little more?

By: tareq

tareq — Wed, 04 Jan 2012 19:54:35 +0000

dear Waled,
i have a case that confused me a bit , i have an a list with main category (4 cat.) and sub category (about 12 sub cat ) now i want to filter it to those cats. , is good to have multiple camel query ( one query for each cat.) or would it be better to get all items in one SPItemCOllection and handle the filtering in my code ?

By: Waldek Mastykarz

Waldek Mastykarz — Tue, 12 Jan 2010 09:13:02 +0000

@Simon: I would definitely agree that it wouldn't be a good idea to use PortalSiteMapProvider for querying 10 items. What you always could do is to program both routines and then abstract them to a single method which would allow you to switch with a single button click/property change.

By: Simon

Simon — Tue, 12 Jan 2010 08:45:48 +0000

ah nice one, always one step ahead ;)

The tough part is working out if the PortalSiteMapProvider is the right choice before you know the volumes.
But thats why I like to use the SiteDataQuery as its used in both the SPWeb.GetSiteData and the PortalSiteMapProvider.GetCachedSiteDataQuery so you can easy switch between the 2 without too much work, also as I can see it performs well :)

By: Waldek Mastykarz

Waldek Mastykarz — Tue, 12 Jan 2010 06:20:53 +0000

@Simon: Thanks for the tip. Have you seen this one: Performance of content aggregation queries on multiple lists revisited?

By: Simon Ovens

Simon Ovens — Tue, 12 Jan 2010 02:57:00 +0000

Great Post!

Another useful comparison and it would be good to know is:
-SiteDataQuery and PortalSiteMapProvider
vs
- CrossListQueryInfo and CrossListQueryCache

hint hint :)

By: Simon Ovens

Simon Ovens — Mon, 11 Jan 2010 23:57:15 +0000

Great Post!

Another comparison which would be useful and good to know is which of the following 2 is faster – SiteDataQuery with the PortalSiteMapProvider or CrossListQueryInfo with CrossListQueryCache

Of course it would have to be over a period of time so that the caching is utilised.

By: Marius C.

Marius C. — Thu, 02 Apr 2009 18:47:43 +0000

Correcting the correction….is not me…is the publishing interface that strips out the generic part (it looks like HTML tag :D), so I add it in old plain HTML and for the 2nd example

By: Marius C.

Marius C. — Thu, 02 Apr 2009 18:44:39 +0000

Yes, indeed you are right about CrossListQueryInfo! To answer your question i need to complete my piece of code as in hurry i forgot one important aspect (the generic part ), So here the correction:
SPContext.Current.Web.Lists["My List"].Cast().Where(item=>item["Title"].Contains("My Filter Key"));

Also, as a slight variation, i've been using the following to retrieve all the lists that contain a specific ContentType (you can imagine complex queries with multiple where clauses, etc…limited just by the need, imagination..and not ultimatelly the performance degradation in some cases!!):

//see here that we use SPList, instead of SPListItem
SPContext.Current.Web.Lists.Cast().Where(item=>item["ContentType"].Contains("My Content TypeName "));

By: Waldek Mastykarz

Waldek Mastykarz — Thu, 02 Apr 2009 16:41:32 +0000

@Marius C.: CrossListQueryInfo is a little bit better than any other querying method. The downside is though, that it's only available in MOSS, so if you're using WSS you should have to fall back to one of the 'basic' classes like SPSiteDataQuery or SPQuery.
As for the lambda expression: I haven't tried running the query in such manner. What I miss though is: how the lambda expression would know that you actually want to access the Items property of SPList?