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.
magine yourself, happily computing when all of a sudden you hear a rather alien sound eminating from your hard drive. Something that sounds, perhaps, like some combination of a roofer banging in a nail, and a miner’s pick as he works on releasing a stubborn piece of ore from a cave wall. Certainly not a good sound to hear coming from the general region of your hard drive on a nice, sunny day. Especially when you have not taken a backup in over two years…Please, learn from my mistake, and next time you hear an odd clicking sound, don’t try to outsmart your already-broken hardware.
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 understand that MySQL as a company wants to recruit paying customers. However, as a community user I have a hard time finding what I want on the MySQL website. Today’s frustration is brought to you by trying to find the documentation.
One of the most frequently needed functionality in the MySQL Proxy is the need to know which server you are on. This is not given, on purpose, by the proxy, because the proxy is supposed to be transparent. It is not supposed to matter which back-end server you are on. However, for testing purposes we often want to know which back-end server we’re on. Thus I developed functionality for SHOW PROXY BACKEND [INDEX ADDRESS OTHER].
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!
Fedora 9 was released on the 13th. I waited a whole three days to make sure I wasn’t going to be the beta-tester. Then I tried out the live release, and finally decided to upgrade my main workstation to Fedora 9 today. To be sure I wouldn’t mess stuff up, I used the DVD installer to upgrade. The upgrade finished fine, but when I rebooted, XChat would not run. Readers — any similar experiences or advice?