V$LOCK Missing Information

In our first BCOUG Tech Day conference, I presented my session “Look Inside the Locking Mechanism”. I presented this topics before a few times and prepared a few demos to show different locking scenarios.

During the BCOUG Tech Day I did the same, while the only difference was that for the demo I used Oracle 12.2 PDB (I think in previous times I always used 11.2). During one of the demos I noticed something strange.

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BCOUG Tech Day 18 Summary

On April 27th (2018) we had our first BCOUG Tech Day conference! If you are reading this and you’re part of an OUG board, you know how stressful and how much work it is to organize such an event. But the bottom line: it was very successful!

I decided to write this post for a couple of reasons: first, I usually write about conferences, and second, to give a little bit of information and stuff to think about if you plan such an event for the first time.

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Did You Know #25 – Archives in FRA

One of my clients is restoring their database backup to another server for some testing. They do it periodically so we can also verify that the backup is good (which is great!). In a few cases, after the restore I saw that the restored database has an incarnation that the original database doesn’t have (and not the one created by the “open resetlogs” after the recovery). This actually caused a problem during the restore, but this restore has a few issues (I started a post about that as well).

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Did You Know #24 – Blocked Instances

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”.

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Tool to Assist with Basic SQL Analysis

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.

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