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Example showing two views that LOOK and ACT the same, but one is 153 times larger

By Andrew Pollack on 10/06/2009 at 01:13 PM EDT

View indexes are the real culprit in performance on so many servers. One reason they're too big, is the use of the wrong @Function. Here's the result of a simple test I tossed together. I did this for my presentation on performance at AdminCamp a week ago. I thought I'd share it here.

Setup:
New database with two forms, both the same other than the form name. Form one has two documents created. Form two has two documents created. What's the difference then? The two documents using form two has have 30,000 response documents on them. The documents created from form one have no responses.

Next, I created four views, with selection formulas as follows:

View #1 -- SELECT form = "TEST1" | @AllDescendants
View #2 -- SELECT form = "TEST1" | @IsResponseDoc
View #3 -- SELECT form = "TEST2" | @AllDescendants
View #4 -- SELECT form = "TEST2" | @IsResponseDoc

In the database itself, views #1 & #2 look identical. Views number 3 and 4 also look identical to each other.

What about the difference in view sizes?

View #2 is 153 Times the Size of #1
and has the EXACT same content

This happens because the @IsResponseDoc formula selects ALL response documents in the database, including those not responses to the actual parents in the view. Those response documents don't display, because their parent isn't in the view -- so they're orphaned -- but they're still in the index. By using @AllDescendants, only responses where the parent is in the view are actually found.



Now imagine the savings if instead of 30,000 documents we were talking about 300,000 documents.


There are  - loading -  comments....

re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Ben Langhinrichs on 10/06/2009 at 03:11 PM EDT
Great tip. Out of curiosity, I went to our internal Helpdesk and went to
Manage Views. The two largest views had exactly this problem, and one was
reduced to a fifth of the size when fixed, the other to about a third of the
size. Not as great as 1/153 of the size, but a substantial and measurable
improvement with no loss of function. Outstanding!

Now, I just have to go run Synopsis on every other large db I have. Sigh!
Why go that route?By Andrew Pollack on 10/06/2009 at 03:23 PM EDT
Just write an agent that runs through the db directory, opens all the views in
the databases, looks at the selection formula (all lotuscript) and does a seach
for that formula command -- you could, if you dare, just replace it and save as
the syntax is the same. Of course, that would cause a bunch of views to
rebuild.
re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Stephan H. Wissel on 10/06/2009 at 04:27 PM EDT
Steal the code here:
http://www.wissel.net/blog/d6plinks/SHWL-7DDMJV

Of course you could change the background color if you find anyt of these:
@now @today @isResponseDoc

:-) stw
re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Dan Soares on 10/07/2009 at 09:22 AM EDT
Andrew... awesome tip !

Dan
re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Theo Heselmans on 10/06/2009 at 03:55 PM EDT
Nice tip, I never use either of these @functions because they were confusing.
Now I'll remember !
re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Chris Blatnick on 10/06/2009 at 04:29 PM EDT
Nice one, Andrew! These are the tips that *every* Domino developer needs to
know.
re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Jerry Carter on 10/07/2009 at 11:26 AM EDT
Impressive space savings!
re: Example showing two views that LOOK and ACT the same, but one is 153 times largerBy Andre Guirard on 02/28/2011 at 03:37 PM EST
This is a good tip, but beware that @IsResponseDoc doesn't behave exactly
identically to @AllDescendants. It's too long to explain here, so I wrote a
blog entry about it, which I'll post when Lotus' servers are back up (at the
moment Littleton's shut down, probably due to a downed wire in the ice storm).


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