A Good Example of Time Wasted

This is a story about letting something be important that is not; poking at — investigating — that unimportant thing over several months without devoting enough time to find out what was really going on; and finally solving the problem.

As readers of http://octopusgrabbus.wordpress.com already know, I’m involved in working on an Automated Meter Reading (AMR) data transfer system. The main functions of the system are to store daily water meter reads from our Itron wireless meter reading system; store and push meter configuration to that wireless system; and snap-shot meter reads for water bills.

From the very moment the daily reads were automated in late May 2010, the python code would spit out this error:

/home/amr/bin/dr_lib.py:123: Warning: Incorrect integer value: '' for column 'MeterID' at row 1
rc = ins_cursor.execute(sql_info[sqlCd.cmd], sql_info[sqlCd.data])
/home/amr/bin/dr_lib.py:123: Warning: Out of range value adjusted for column 'MeterID' at row 1
rc = ins_cursor.execute(sql_info[sqlCd.cmd], sql_info[sqlCd.data])
Downloading files from Itron.

There seemed to be two obvious ways to solve this problem:


  test_meter_val = int(meter_val)
except ValueError:
  meter_val = 0


  rc = \
  ins_cursor.execute(sql_info[sqlCd.cmd], \
except MySQLdb.Error, e:
  raise e
except MySQLdb.Warning, e:
  print("Here is the MySQL warning ", e)

Well as it stands, the MySQLdb.Warning never triggered, because I needed to re-read this article — http://dancingpenguinsoflight.com/2009/10/catching-warnings-from-the-mysqldb-module/

Then I finally got the plain try except block to work.

However, getting it to work required more than a cursory glance and a one line code fix. It required a test system where the database was not the production database; hence no production data was at risk.

The moral of the story is this. Don’t chase down this kind of warning, unless it is going to cost you something big, and if you are going to chase down the problem, sink enough time in it to understand fully what is going on. I failed on both counts.


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