Not always the more the better. ORA-04031 provoked by parallel servers

I thought is worth to write about this incident that happened in one of my servers a couple of months ago. The reason is to show that to add or increase resources is not always the right approach to solve a problem.

ASL - My thermometer for the database

I suppose that most of you, DBAs,  have been asked sometime questions like "How is the general performance of the database?",  "I think there are a problem somewhere, is the database running well?", "Yesterday, at some moments of the day, the database run slow. Can you check what happened?".

Sure, those questions sound familiar to you. How could we give an answer to them?. Of course, we can take a look at the typical ratios, check AWR or Statspack reports, take a look at the OS, etc, etc.

Installation of Oracle Grid/RAC 11.2.0.4 on RHEL 7 or Oracle Linux 7

Some days ago, I had to install Oracle 11.2.0.4 on Red Hat Linux 7 and Grid Infrastructure for a standalone server. What I expected to be a quick task turned to be trickier than expected. Here outlined are the steps for the installation.

Data Guard: Using a Physical Standby database for testing

Here is a test I made. Usually, a standby database is used to provide contingency. But
we can use it sometimes for some testing. Let's say we want to try a job, to check some performance issues, to test a new application, etc.. but we do not want to do it in the main database. Here is a way to do it:

A free troubleshooting tool. Session Sampler

As I needed a tool that permit me to sample the activity of active sessions in Oracle and analyze the data, I wrote a tool for sampling in Python.

This tool is written for troubleshooting and not for continuous monitoring. Is not a substitute for ASH, but can be very helpful to see what happens in the database at one moment in time.

How to extract the hints we need from a SQL Query.

Let's say you have a SQL query running in one database and you need to run it in another similar one with the same execution plan perhaps only
once just to see its behaviour. Let's say you think "Hey, I could do it if I had the appropiate hints". But you do not know for sure
which hints exactly use. Here is a way to retrieve them!:

Troubleshooting a slow RMAN backup

(As I always do, the names of the databases and files are not the real ones, but the numbers are).

Yesterday we got a complain for one client. He said that the RMAN backup of the database was running on working hours and that should not be. I looked at the times of the backup along the week and saw that the backup took much longer than expected.

Recovering a deleted datafile using lsof

Here is a little trick that can be useful in case of a accidental delete of one datafile.
I do not recommend or encourage anyone to do it, but could be useful under certain specific situations.