February 21, 2011 at 6:20 am
Hi
I have a package with 10 data flows. All the data flows contains OLE DB Command for which are updating my FACT Stagaing table.
for initial load it is taking hugh amount of time. As it is updating 1.5 to 2 Lakh records.
I don't want to write a Direct SQL Update statment for this.
Can anyone suggest any way to increase the execution of the same.
Can we avoide the OLE DB Command.
Thanks
February 21, 2011 at 6:28 am
Send all of the rows you will be updating to a staging area (as INSERTs), then perform a single T-SQL update at the end.
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February 21, 2011 at 7:42 am
saurabh.deshpande (2/21/2011)
I don't want to write a Direct SQL Update statment for this.Can anyone suggest any way to increase the execution of the same.
Can we avoide the OLE DB Command.
Is there a reason you don't want to write a SQL Update statement?
As Phil said, the staging table with set-based update is the best option. You can also write an INSTEAD OF trigger on the staging table that changes the INSERT statement into an UPDATE statement. That way you can use the staging table as a destination in your dataflow and that's it. On the other hand, you'll have to maintain triggers.
(So Phil's option is still preferred)
On a sidenote: why has an initial load so many updates? What is there to update?
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February 21, 2011 at 7:48 am
Not sure about that trigger idea - nice thought, but won't it just end up doing the same RBAR updates, albeit on the server?
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February 21, 2011 at 11:07 am
Phil Parkin (2/21/2011)
Not sure about that trigger idea - nice thought, but won't it just end up doing the same RBAR updates, albeit on the server?
If you implement the INSTEAD OF trigger set-based, there is no problem. It is quite easy with the use of the INSERTED table.
I have never used this approach, I've read it in an article somewhere. Useful when you don't have a staging area (or not the space for it) and you don't want to stress out tempdb.
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February 21, 2011 at 1:54 pm
Koen Verbeeck (2/21/2011)
Phil Parkin (2/21/2011)
Not sure about that trigger idea - nice thought, but won't it just end up doing the same RBAR updates, albeit on the server?If you implement the INSTEAD OF trigger set-based, there is no problem. It is quite easy with the use of the INSERTED table.
I have never used this approach, I've read it in an article somewhere. Useful when you don't have a staging area (or not the space for it) and you don't want to stress out tempdb.
So the 'real' inserts go directly into the destination table and the 'update' inserts go into the staging table, where an instead of trigger picks them up from 'inserted' and fires them into the destination table via an UPDATE - is that what you mean?
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
February 22, 2011 at 12:18 am
Phil Parkin (2/21/2011)
Koen Verbeeck (2/21/2011)
Phil Parkin (2/21/2011)
Not sure about that trigger idea - nice thought, but won't it just end up doing the same RBAR updates, albeit on the server?If you implement the INSTEAD OF trigger set-based, there is no problem. It is quite easy with the use of the INSERTED table.
I have never used this approach, I've read it in an article somewhere. Useful when you don't have a staging area (or not the space for it) and you don't want to stress out tempdb.
So the 'real' inserts go directly into the destination table and the 'update' inserts go into the staging table, where an instead of trigger picks them up from 'inserted' and fires them into the destination table via an UPDATE - is that what you mean?
Basically. I tracked down the article:
http://sqlserverpedia.com/blog/sql-server-bloggers/ssis-%E2%80%93-performing-an-upsert/
Instead of a staging table, he uses a view on top of the destination table where he puts his "update inserts".
Advantages: no need for a staging table, so less disk I/O. Bulk load and set based updates.
Disadvantages: you'll have to maintain views and triggers for every destination table.
I have never used this before, but I like the idea of using this when there is absolutely no space for staging tables.
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My blog at https://sqlkover.com.
MCSE Business Intelligence - Microsoft Data Platform MVP
February 22, 2011 at 12:29 am
That's a good article, thanks! It's always good to have read about this stuff - one day, an ideal scenario will present itself and I'll be able to suggest a great solution.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
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