我有一个简单的数据库,大约有3900个条目,使用一个带有django.views.generic.list_detail.object_list的泛型视图(通过paginate_by)来浏览数据库中的数据,但是有些查询非常慢。
django optimization page
.
profiling middleware
长查询的绝大多数时间都花在数据库上:
735924 function calls (702255 primitive calls) in 11.950 CPU seconds
Ordered by: internal time, call count
ncalls tottime percall cumtime percall filename:lineno(function)
35546/3976 4.118 0.000 9.585 0.002 /usr/local/lib/python2.6/dist-packages/django/db/models/query.py:1120(get_cached_row)
30174 3.589 0.000 3.991 0.000 /usr/local/lib/python2.6/dist-packages/django/db/models/base.py:250(__init__)
---- By file ----
tottime
47.0% 3.669 /usr/local/lib/python2.6/dist-packages/django/db/models/base.py
7.7% 0.601 /usr/local/lib/python2.6/dist-packages/django/db/models/options.py
6.8% 0.531 /usr/local/lib/python2.6/dist-packages/django/db/models/query_utils.py
6.6% 0.519 /usr/local/lib/python2.6/dist-packages/django/db/backends/sqlite3/base.py
6.4% 0.496 /usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py
5.0% 0.387 /usr/local/lib/python2.6/dist-packages/django/db/models/fields/__init__.py
3.1% 0.244 /usr/local/lib/python2.6/dist-packages/django/db/backends/util.py
2.9% 0.225 /usr/local/lib/python2.6/dist-packages/django/db/backends/__init__.py
2.7% 0.213 /usr/local/lib/python2.6/dist-packages/django/db/models/query.py
2.2% 0.171 /usr/local/lib/python2.6/dist-packages/django/dispatch/dispatcher.py
1.7% 0.136 /usr/local/lib/python2.6/dist-packages/django/template/__init__.py
1.7% 0.131 /usr/local/lib/python2.6/dist-packages/django/utils/datastructures.py
1.1% 0.088 /usr/lib/python2.6/posixpath.py
0.8% 0.066 /usr/local/lib/python2.6/dist-packages/django/db/utils.py
...
---- By group ---
tottime
89.5% 6.988 /usr/local/lib/python2.6/dist-packages/django/db
3.6% 0.279 /usr/local/lib/python2.6/dist-packages/django/utils
...
我可以理解为什么SQL查询可以随着所选条目的数量而扩展。但是,我不明白为什么剩余的CPU时间会受到影响。这非常违反直觉,我想知道是否有任何调试/分析技巧可以帮助我。
将django-1.2.3与sqlite、python2.6、apache2 prefork一起使用(尽管切换到mpm worker并没有显著改变)。任何提示/技巧将非常感谢。内存使用似乎也不是一个因素(机器有2Gb的RAM,free说只使用了300Mb(另外还有600Mb的缓存),数据库和机器在同一台服务器上。
发现了我的错误
基本上有些愚蠢的东西,比如:
if len(queryset) == 1:
return HttpResponseRedirect( fwd to object_detail url ...)
return object_list(request, queryset=queryset, paginate_by= ...)
