Nice you tested it out! You are right about that kind of optimization is really
a micro optimization and would only help if there were a bunch of those related.
De: Josh Smeaton
Enviado el: lunes, 16 de noviembre de 2015 23:48
Para: django-developers@googlegroups.com
I finally
I finally got djangobench running, but I find the results too
unpredictable. I resorted to some simple timeit measurements which I've
shown here: https://gist.github.com/jarshwah/f28d84987aadc7bcb2f5
Result.. moving the if outside of the loop has about a 15% decrease in time
taken for that bloc
Hey,
Nice to see most of the performance differences are resolved. Most of the
heavy lifting will actually be compiling the SQL that is going to be
executed now I think. You might want to take a look at generating the SQL
yourself and executing directly with connection.cursor if you're still
h
We don't patch the docs for versions of Django older than the latest stable
release except in critical cases. For one, this causes problems for the
translated versions of the docs because there's no process for updating
those older versions. Also, Django 1.7 will be unsupported in a couple
week
You beat me to it. Yes I have just tested under django 1.8.6, and the issue
I started this with is gone, both values_list and a direct raw query
perform as good, so this is definetly an issue only on django 1.7.10 or
less.
I can not test django 1.9 since my project is not really compatible with
The version of Django you use is going to have a large (code) impact on
what is actually happening when calling values_list. The
Values[List]QuerySet classes are gone in 1.9. 1.8 implemented a
different/better way of converting values from the database to python.
from_db_value came about in 1.8
Hi, I have downloaded the actual source code, and I have probably forgot to
mention that I'm using django 1.7.10.
It seems like the compiler.py module got a little bit improved since then,
what used to be a big and highly inefficient loop with many if conditions
inside was reduced to a small loo
Interesting, maybe because I'm using MySQL with mysqlclient connector, but
running the straight query with the django cursor wrapper always returns the
correct data types, even dates with its it time zone when time zone is enabled,
was it all coincidence? Would using a different backend break wi
To give some brief historical context: values_list has been around a LONG
time, so I wouldn't say anyone has consciously designed it with performance
in mind above "it's faster than complete model loading".
The most noticeable thing which your code does not do which an
implementation of values lis
I don't think there is much database backend specific logic as far as
values_list() goes, but if you get something working on SQLite and send a
pull request, we can easily run it on all database backends.
For performance testing, you might find
https://github.com/django/djangobench/ useful.
On
Hi, thanks for the response! I have never developed nor ran the django test
suite, I can certainly try as you mentioned, I was hoping for anyone that
actually implemented values_list to give me a solid reason to not do any change
as I'm probably wrong and the current way it is implemented is the
I don't think anybody has anything against making values() or
values_list() queries faster. The question is purely about
implementation. If you can offer something that is faster than the
current code without introducing backwards incompatibilities or making
the code a lot more complex, then such a
I would like to add, that minor change on a critical query meant an increase
from 37 to 47 requests per second on a benchmark test with apache, that's a 22%
improvement that will be bigger on larger results (this was just with 700 rows
result set), compared to using some pagination with a limit
After some testing I have found out that even when using values_list to prevent
massive object creation when fetching data, it is from 2 to 3 times slower tan
using directly a cursor.execute query through the django cursor.
The issue started here
http://stackoverflow.com/questions/33726004/dja
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