I had a bad night last Thursday.
After patching two test RAC databases and one production RAC with 180417 DB Bundle Patch (and some one-offs), I got to the point where it was time to update the most critical RAC system.
We were really looking forward to this as we had hit a few bugs that this DBBP and one-offs should fix. But boy, did that go wrong…
Continue reading “Bug When Patching Production”
I just came back from RMOUG Training Days conference. It was my first time in Colorado (and obviously my first RMOUG training day) and it was really great (I wrote about it in another post).
During my second session (From 4 Minutes to 8 Seconds – about a real SQL tuning case I had quite a few years ago), I mentioned that one thing that I usually do when I see a query and need to analyze it, is to take a piece of paper and draw the tables and relations between them. When I later look at the execution plan and try to understand what Oracle does, it helps a lot if I know the structure of the tables. There is a big difference between queries built like a “star” (a single table in the middle, while the others are joined to it) or a “line” (each table is joined to the next one), or any other structure.
Continue reading “Tool to Assist with Basic SQL Analysis”
In the previous post I talked about the order of predicate execution based on the predicate position and inline view.
As promised, in this post I’ll add statistics and see what happens.
Continue reading “Order of Predicate Execution #2”
In my previous post, I wrote about the parsing operation and what happens first. In the footnote I said that the order doesn’t affect performance, the cost based optimizer doesn’t care about the order of stuff in the query, right? Well, not quite.
Continue reading “Order of Predicate Execution #1”
Over the years I’ve heard and learned quite a lot about how Oracle does stuff. Some of it was logical, some just details to remember (I have a really lousy memory, but somehow, I actually remember some of the details). Not too long ago I wrote a query and got a parse error, and that lead me to write this post (and a couple more that will follow).
Continue reading “Parse Order and Analysis”
If you don’t know that by now, OTN (Oracle Technology Netowrk) has changed its name to ODC (Oracle Developer Community), so OTN Appreciation Day becomes ODC Appreciation Day.
This initiative started by Tim Hall from ORACLE_BASE last year. In this day, every blogger writes something to thank Oracle for. You can read about the concept and “rules” here.
Continue reading “ODC Appreciation Day – Plan Statistics”
After talking a bit about the AWR report (if you haven’t read the previous posts, you can find part 1 here and part 2 here), I think one of the best ways to understand it is to talk about real examples. In this part I’ll give you a few examples and tips regarding the report.
Continue reading “Reading AWR Report – Part 3”