Posts Categorized: Pythian
In one of my previous posts I mentioned SYSTEM_PRIVILEGE_MAP view. Taking this thread further, I looked into another nice view – V$ENABLEDPRIVS – showing the privileges enabled for the session at the moment. It should be pretty useful if you decide to add some diagnostics into your application. You might also find it very helpful to call from PL/SQL.
We humans are not able to process large amount of precise data. In any human–readable report, we don’t need more than ten or twenty lines of numbers. Every time we look at processes or data more complex that that, we employ simplifications — graph trends, mind–mapping, aggregations, and so on. How will we make computers process information just as humans do? Perhaps we can find the answer inside ourselves if we figure out how our minds work. We recognize images even though our brain is not capable of processing huge amounts of data in milliseconds.
MySQL – No Index Used With ORDER BY + LIMIT and DISTINCT. This is actually a follow up on my previous post. Developers tried to rewrite all statements and even overdid it. As we say in Russia – “teach fool how to pray and he will break his forehead”.
Doug Burns posted photos with his new teammates on his blog, and I felt they deserved a mention here too.
Robert Treat has published the 27th edition of Log Buffer, the weekly review of database blogs, on zillablog.
Filesorts and temp tables are a necessary evil in MySQL, used when MySQL must sort the data before returning the output to the user. They are the most common issue with slow queries in MySQL, the main reason being that if the output is too large, you can kiss goodbye in-memory performance, and say hello to disk access.
Read Gary Krakow’s review of SanDisk’s 32GB, 1.8-inch solid-state drive (SSD)
Oracle 10.2.0.3 Patchset – Known Issues and Bugs. Oracle 10.2.0.3 patchset is not functional on Solaris SPARC 64bit platform with datafiles on Veritas VxFS.
Today is the first time I had to look at MySQL performance. Tiny database as web application back-end was having significant performance issues with spikes of CPU workload. After identifying problematic queries, I found a pile of statements using IN subqueries. I asked around and our MySQL experts assured me that this is one of the minor and not so disturbing issues, in fact. I can’t imagine what those disturbing issue are. I guess Oracle XE does have some advantages over MySQL for small installations.
Doug Burns is finally here in Ottawa. You must see his smile in the airport – somehow he managed to read my comment and already expected me while I thought it would be surprise.