Get random items

[fehaar]

Is it possible with NoRM to get a random set of results back from a
query? Say I want to display three random news items on my front page.

Thomas Gravgaard

[Dmitry Aleksandrov]

Hi,

You can use .Skip(<<randrom_int_here>>).Take(3) calls

Regards,
Dmitry

[fehaar]

Yes... That could do it in some cases. But it would always preserve
ordering.

When I used MSSQL i could use "ORDER BY NEWID()" and get a random
sequence out every time. A similar functionality could be useful.
Could it be done with some neat map/reduce function?

/ Thomas

On 28 Sep., 15:46, Dmitry Aleksandrov <alexandrov.dmi...@gmail.com>
wrote:

[Ken Egozi]

order by NewID can get extremly slow with large data sets

if you have sequential ids you can randomize three values, then ask them with an $in query

if there are a lot of gaps, you can issue three queries, each will ask for the first item with key >= random(minvalue, maxvalue). 

three get-by-id queries from Mongo should be at least as fast as using ORDER BY NEWID (on a large enough dataset)

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[fehaar]

It is not because I am worried about speed or comparing with how
things are in SQL. I am using Mongo because it rocks - especially when
using NoRM. ;-)

So I am just trying to trying to solve this particular issue.

Right now I am not using sequential ID's. But that might be the way to
go if there are no other solutions to the problem.

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> > .

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> Ken Egozi.http://www.kenegozi.com/bloghttp://www.delver.comhttp://www.musicglue.comhttp://www.castleproject.orghttp://www.idcc.co.il- הכנס הקהילתי הראשון למפתחי דוטנט - בואו בהמוניכם