Even after years of working with something, you can always learn new stuff. Today I tried to create a standby database using the duplicate command. When you duplicate a database you need to connect to both instances (primary as target and standby as auxiliary) using SQL*Net (and not “/”). Since the standby is in nomount, the listener blocks connections to it, so when trying to connect to it using the listener we get “ORA-12528: TNS:listener: all appropriate instances are blocking new connections”.
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.
This is a short note just to say I’m happy to have my first GitHub project.
A few months ago I wrote a blog post and a python script (on gist) to analyze the listener log file. A few weeks later I got a message from Adric Norris who asked me to create a proper GitHub project, as with gist, people cannot improve and add code.
I posted my first challenge almost 2 years ago and there was a lot of interest in it. Today I post another one.
Many years ago I saw this strange thing and it took me some time to realize what’s going on. Since then I ran into this scenario a few times, solving it instantly (and make a good impression at the same time).
I had a talk with a customer/colleague that got me thinking about a strange case of multitenant configuration. The chat was about an environment with two data centers and data guard.
During the discussion, I realized that there might be an issue with listener services, so I checked it and this post is the result