In my previous post, I described the most common cause for unstable plans due to bind peeking — histograms. It is now time to move forward and take a look at another case, namely range-based predicates. Strictly speaking, the cases I’m going to describe can appear without range-based predicates as well, you just need to remember that a range-based operation doesn’t necessarily imply a range-based predicate.
The 98th edition of Log Buffer, the weekly review of database blogs, has been published on Jeff’s SQL Server Blog.
The latest news — there is a new web site — ashmasters.com. This is the place where you can leave your comments and questions about ASH and ASHMON. Wondering how you can query ASH data? There are some ready to use queries. Have a cool idea how to use ASH and query ASH data? Share it there and have it added to the ASH Masters queries toolkit.
Recently, I had a few email exchanges — on the Oracle-l list and offline — about HW enqueue contention. A few interesting observations emerged from test cases I created during that discussion.
Todd Hoff, has an extremely well-written and edutaining article about how scaling to a million or more users requires jettisoning more or less everything we know and love about relational modeling. Even though he uses bigtable as his example, in reality this approach works well with relational datastores like MySQL and Oracle too, you just have to think about your data differently and use the databases differently. So I’m including this article in the MySQL and Oracle categories because I think it would be of interest.
I came across what appeared to be a change to the rules for licensing Oracle Standard Edition — a change that appears to be subtle on the surface, but one that could have significant and surprising repercussions.Mistake or not, though, there is a clear moral to this story. You need to read the license agreement, even when you are only planning a purchase. Trust me — reading the license after the P.O.s have been cut will not make you look good in a situation like this. And not reading the license would be a major mistake indeed!
The 97th edition of Log Buffer, the weekly review of database blogs, has been published on Brian “Krow” Aker’s Idle Thoughts.
I decided to reprise my commentary on Oracle RAC and the gv$ views after reading Patrick’s comments on my previous post. It is always encouraging to know that someone is kind enough to read your work and provide insightful feedback – many thanks to him! There are two questions that I wanted to answer here: Can you use the gv$ views with a non-RAC environment? What do the WHERE clauses in a good block-checking script do?
As some of you probably already noticed, there was a thread on AskTom discussing the scalability tests I did back in 2007. You are welcome to read the entire thread, but in a nutshell, Tom Kyte claimed that my tests did not reflect how one would use the result cache in the real world. What is “real world?”
Karun Dutt and I managed to get DBD::Oracle 1.21 to install on a 64-bit Linux OS against the Oracle 11 full client. Here’s what we did.