This is an update on Date formatting in python or in PostgreSQL where the test wasn't done very well. The solution using Python for the formatting created a new
DateTime object each time for each formatting because the
time_stamp extracted from the database was a string. That would be beneficial to the Python formatting alternative but that's not the whole point. I suspect that the way I did the experiment last time (code is lost by the way) was wrong and didn't focus on the correct benchmark.
In this, my second attempt, I've done a more correct test and tried it on 500 selects. 500 formatted in SQL and 500 formatted in Python. The results are even more outstanding for PostgreSQL than last time.
Here are the results:
times1 (python formatted) 0.113439083099 times2 (sql formatted) 0.00697612762451
That means that doing the date formatting in SQL is 16 times faster!!
Bare in mind that this is optimization and you always have to be careful when doing optimization. For example, the SQL database shouldn't get involved in the presentation and if you need to use a different locale you might to change your application in two places which is risky.