January 2008

As part of a presentation I'm preparing, I would like to get an idea of RMAN usage in the Oracle Community.

If you can spare a couple of minutes, please fill out this 10 question multiple choice survey: RMAN Usage Survey

Update:

It seems I made a poor choice of online Survey site.

To get more than 100 responses to this survey, a "Professional" version must be purchased. At a rate of 1 or 2 surveys a year (for me) that is not exactly practical.

Sharing the Survey results also requires the Professional version.

Here's a summary of the results in MS Excel.

RMAN Usage Survey Results

I read this post by Laurent Schneider yesterday. In the comment section Tom Kyte already explained what the issue was about, but I’ll expand this explanation a little.

The question was why should the apparently invalid statement below work? I mean there is no such column nor number as “1.x”), yet the statement works ok:

SQL> select 1.x from dual;

         X
----------
         1

The column header gives a good hint what happened above. Oracle has treated the X as the column alias.

Let’s remove the “x” and see:

SQL> select 1. from dual;

        1.
----------
         1

Now all works as expected, “1.” is treated as number ( 1. = 1.0 )

Oracle has evolved over time to much more than just a plain relational database. One option is to use Oracle as an expensive calculator.
When researching or demoing Oracle, it’s quite convenient to do number calculations directly on sqlplus prompt, especially if dealing with internals where lots of stuff is about addresses and offsets shown in hex.
Here’s the script what I use for such purposes: https://github.com/tanelpoder/tpt-oracle/blob/master/calc.sql.
It usually saves me couple of seconds every calculation as I don’t have to reopen the calc.

I was once asked a question, why does Oracle change its parameter count during session lifetime?

The question arose from the following observation that v$parameter shows more parameters after you adjust some hidden parameter value:

SQL>
SQL> select count(*) from v$parameter;

  COUNT(*)
----------
       288

SQL>
SQL> alter session set "_complex_view_merging"=false;

Session altered.

SQL> select count(*) from v$parameter;

  COUNT(*)
----------
       289

Looks like the parameter count was just increased by one!

“It sure seems like the hidden parameter don’t exist before they are actually modified”: