Tip #447: To filter or not to filter – functional view

This seems to be the week of unsupported tips. I know, we said it before: Swim between the flags, and Use filtered views even if you use stored procedures.

But what do you do if this particular report’s query is a monstrosity, adding custom indexes don’t help, and any attempt to restructure it just makes it worse? Sounds familiar?

Consider this simple pre-filtered SQL that returns us all invoiced and delivered line items in the last financial year:

declare @fromutc datetime, @toutc datetime
select 	@fromutc = dbo.fn_LocalTimeToUTC('1-jul-2014'),
	    @toutc   = dbo.fn_LocalTimeToUTC('1-jul-2015')

select 
   CRMAF_FilteredContact.contactid, 
   CRMAF_FilteredContact.fullname, 
   i.datedelivered, 
   i.name, 
   id.actualdeliveryon, 
   id.baseamount, 
   id.tax, 
   id.extendedamount
from
   FilteredContact as CRMAF_FilteredContact
   inner join FilteredInvoice i 
      on CRMAF_FilteredContact.contactid = i.contactid
   inner join FilteredInvoiceDetail id 
      on id.invoiceid = i.invoiceid
where
	id.actualdeliveryonutc 
	between @fromutc
	    and @toutc

If everything else fails (including scheduling the report overnight), my last resort is to isolate some of the views into a separate function and, gulp, replace the filtered views with the base views. In the case above, that could be something like that:

create function [dbo].[OutsideTheFlags]
   (@fromutc datetime, @toutc datetime)
returns table
as return (
select 
   i.ContactId,
   i.datedelivered, 
   i.name, 
   id.actualdeliveryon, 
   id.baseamount, 
   id.tax, 
   id.extendedamount
from
   Invoice i 
   inner join InvoiceDetail id 
      on id.invoiceid = i.invoiceid
where
	id.actualdeliveryon 
	between @fromutc
	    and @toutc
)
GO	
-- This is important. Otherwise won't run
GRANT SELECT 
ON [dbo].[OutsideTheFlags]
TO [DOMAIN\ReportingGroup {GUID}]
GO

and then the reporting query becomes:

declare @fromutc datetime, @toutc datetime
select 	@fromutc = dbo.fn_LocalTimeToUTC('1-jul-2014'),
	    @toutc   = dbo.fn_LocalTimeToUTC('1-jul-2015')

select 
   CRMAF_FilteredContact.contactid, 
   CRMAF_FilteredContact.fullname, 
   i.datedelivered, 
   i.name, 
   i.actualdeliveryon, 
   i.baseamount, 
   i.tax, 
   i.extendedamount
from
   FilteredContact as CRMAF_FilteredContact
   inner join dbo.OutsideTheFlags(@fromutc, @toutc) i  
      on CRMAF_FilteredContact.contactid = i.contactid

Original query: 1.9 sec, new one: 0.2 sec, 900%+ improvement. YMMV, of course. (And, yes, I cheated, times still need to be converted to local)

When performing this unsupported gymnastics, be very, very careful: you’ll lose lookups and optionsets expansion, the dates will be UTC-only, etc. Not to mention that the above gives blanket access to all invoices for all users. Test, test, and test.

The usual disclaimer: use at your own risk, contains small parts, choking hazard, swim between the flags. Not tested on animals, or children. Good luck making it work for CRM Online.

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2 thoughts on “Tip #447: To filter or not to filter – functional view

  1. Daniel Kasimirowicz says:

    I like these kind of tips. And I know, you guys like the German word Spie├črutenlaufen. We would use the following disclaimer here:

    Zu Risiken und Nebenwirkungen fragen Sie Ihren Arzt oder Apotheker.

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