Luck is always not at your side:

Working under pressure is good, until or unless you know what you are doing and following the standard procedures. The biggest mistake of the life is believing in luck and thinking that everything will be happen as per your plans. If you are doing things by believing in luck, not by skills, then you are doing stupidity.

Don't make any changes in production code, with your assumptions. John doe had done once, and whole week he had nightmares because that generated 300 false alarms. So here's the story:

John Doe is a Database admin, and he is happy and feel comfortable in his role. One day he was working with lots of stuff, and got a message on his chat to fix his old code. An old script is failing, as there is a change in the environment. The name of new hostname(machines) have more characters as compare to old machine. Earlier it's used to be 10 characters, now its 20.

The code was like below:

First part is to collect data

set lines 80

— col hostname for a10 <= Old one

col hostname for a20 <= John Doe changed directly into production

spool /tmp/filedata.lst

select hostname, filename, size from dummyTable

spool off

Second part is to compare the filesize, and generates the alarm if it's lesser than 50 MB.

while read line

do

filesize=$(awk '{print $3'} $line)

if [[ "$filesize" -lt 50 ]]

then

call_function_create_alarm

fi

done < /tmp/filedata.lst

John doe played over smart and changed directly in the production code. He was not sure on what he had done.

3 days passed, the job ran. He got a call as the code generated 300 false alarms.

Is it nightmare or real?

What happened wrong here:

The structure was like this:

Old one:

hostname — field size 10

filename — field size 55

size — field size10

Everything was working fine, because the total field size was under threshold of 80. The day John Doe changed the field size of hostname to 20, the threshold crossed and bang.

Earlier file look like this:

hostname filename size

hostname filename size

hostname filename size

hostname filename size

Now the structure changed to:

hostname filename

size

hostname filename

size

hostname filename

size

and as there is no 3rd column, the code failed and generated false alarms. So, never trust your luck, don't play smart. Follow the procedure, take your time, always aware of impact of your changes, test your code into test environment before releasing to production, and seriously, luck is not always with you.