Ian,
Thank you for the prompt reply!
I am observing the same behavior in the Django shell. Here the actual
query runtime is about the same between Oracle and PostgreSQL back-
ends, but the total turnaround time is about 18 times longer with
Oracle. I believe the following code demonstrates this case:
from django.db import connection
import minilims.log.models as log
import time
time_list = []
for n in range(0, 20):
t1 = time.time()
entries = log.Param.objects.filter(log = 6).order_by('stuff', 'id')
entry = [x for x in entries]
t2 = time.time()
time_list.append(t2 - t1)
print len(connection.queries), 'queries ran.'
average_time = sum(time_list) / len(time_list)
# display minimum, average, and maximum turnaround time
print min(time_list), average_time, max(time_list)
# display average query time
print sum([float(x['time']) for x in connection.queries]) /
len(connection.queries)
The above code in the shell using a PostgreSQL backend reports:
>>> # display minimum, average, and maximum turnaround time
>>> print min(time_list), average_time, max(time_list)
0.203052997589 0.211852610111 0.234575033188
>>>
>>> # display average query time
>>> print sum([float(x['time']) for x in connection.queries]) /
>>> len(connection.queries)
0.0557
However, running the same code with an Oracle back-end, after
restarting the shell, results in:
>>> # display minimum, average, and maximum turnaround time
>>> print min(time_list), average_time, max(time_list)
3.59030008316 3.64263659716 4.33223199844
>>>
>>> # display average query time
>>> print sum([float(x['time']) for x in connection.queries]) /
>>> len(connection.queries)
0.05825
Any ideas?
Thanks!
DW
On Feb 8, 8:58 am, Ian <ian.g.ke...@gmail.com> wrote:
> On Feb 7, 9:44 pm, dw314159 <dw314...@gmail.com> wrote:
>
>
>
> > Django gurus:
>
> > Hello, I am experiencing very slow performance with Django when
> > connected to an Oracle database. The exact same Django application
> > runs far faster with PostgreSQL and SQLite, with the same source data
> > loaded into each database. Looking at the information embedded in
> > “connection.queries” after making an Oracle query through Django, it
> > appears that the queries themselves run very quickly (runtimes are
> > comparable to those measured with PostgreSQL and SQLite), but the
> > whole turnaround time for a query in Oracle far exceeds the reported
> > query time.
>
> > I’ve tried the built-in Oracle backend engine and django-oraclepool
> > 0.7; neither improve performance. (With django-oraclepool, I also gave
> > sufficient time for the connections to pool before taking
> > measurements). Using cx_Oracle outside of Django on the same
> > workstation to connect to the same Oracle database, the query
> > turnaround time is very quick.
>
> > Is this problem connected to the fact that Django is reported to drop
> > the database connection between queries, and therefore must reconnect
> > to Oracle every time a query is executed? Or is there a Django
> > configuration option that must be specified to make the best use of
> > Oracle?
>
> Django actually closes the connection after each HTTP request, not
> each individual query. This means that if you were running your
> timing tests in a request-less environment (i.e. through the Django
> shell), you would not expect to see any slowdown caused by this. It
> also means that if you are running more than a few queries to serve
> each request, the overall effect may be less noticeable.
>
> Have you tried tracing the code during a request? It would be helpful
> to have at least a general idea of where it's spending so much time.
>
> Cheers,
> Ian
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