I was recently working on tuning – production environment, which had number of materialized views which were scheduled to complete refresh during off hours.
This complete refresh process was very time consuming, also producing a large amount archivelogs & undo.
Customer was complaining about sudden change in materialized view behavior, after they upgraded database from 9i to 11g.
After reading Oracle documentation about materialized views I found, the reason for this sudden behavior change.
From 10g, Oracle has changed the default parameter value of ATOMIC_REFRESH in the DBMS_MVIEW.REFRESH package.
In earlier releases (before 10g) the parameter was set to FALSE by default but now it is set to TRUE, which forces a DELETE of the materialized view instead of TRUNCATE, making the materialized view more “available” at refresh time.
Advantages of ATOMIC_REFRESH => FLASE
- No or very less archive generation
- Complete refresh process is very fast as compared to process with ATOMIC_REFRESH => TRUE
Disadvantages of ATOMIC_REFRESH => FLASE
- Unavailability of data during the refresh process, which could be unacceptable to application and business user.
After discussing with customer, I made changes in refresh methodology so as to use ATOMIC_REFRESH => FLASE.
Time Taken Archive generation Before Approx. 43 minutes Approx. 68 After Approx. 6 minutes Approx. 7
Usage:
EXEC DBMS_MVIEW.REFRESH(‘MVIEW1’, METHOD => ‘C’, ATOMIC_REFRESH => FALSE);
Hope so this post is useful for you 🙂
Cheers
Regards,
Adityanath
Categories: Administration
Adityanath's Oracle Blog 
Like!! Really appreciate you sharing this blog post.Really thank you! Keep writing.
whoah this weblog is wonderful i love reading your articles.
Stay up the great work! You understand, many individuals are hunting around
for this information, you could help them greatly.
I’m not that much of a online reader to be honest but your sites really nice, keep it up! I’ll go ahead and bookmark your website to come back later. All the best
I believe this website has got some rattling wonderful info for everyone : D.
Good post. I will be dealing with a few of these issues as well..
It’s remarkable for me to have a web site, which is beneficial
for my knowledge. thanks admin
my blog :: zipper wallet insert for chic sparrow waypoint
Wow! After all I got a website from where I can actually obtain valuable data
concerning my study and knowledge.
This piece of writing provides clear idea designed for the new users of blogging, that really how to do running a blog.
Awesome issues here. I am very glad to look your article.
Thanks so much and I’m having a look forward to touch you.
Will you kindly drop me a e-mail?
I blog quite often and I genuinely thank you for your content.
This article has really peaked my interest. I am going to
bookmark your site and keep checking for new information about once a week.
I opted in for your RSS feed as well.
Hi there, all is going sound here and ofcourse every one is sharing information, that’s in fact excellent, keep up writing.
Hi there, I found your blog via Google at the same time as looking for a related matter, your web site got here up, it appears to be like great. I’ve bookmarked it in my google bookmarks.