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Fixed #14231 -- Added an index to the expire_date column on the Sessi…

…on model. Thanks to joeri for the report, via Frodo from Medid.

This won't affect any existing session tables; see the release notes for migration instructions.

git-svn-id: bcc190cf-cafb-0310-a4f2-bffc1f526a37
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1 parent 90ac023 commit ea85d4303d9b58704ebdea5b88bbd0dbfd6ab30c @freakboy3742 freakboy3742 committed Oct 28, 2010
Showing with 19 additions and 1 deletion.
  1. +1 −1 django/contrib/sessions/
  2. +18 −0 docs/releases/1.3.txt
@@ -45,7 +45,7 @@ class Session(models.Model):
session_key = models.CharField(_('session key'), max_length=40,
session_data = models.TextField(_('session data'))
- expire_date = models.DateTimeField(_('expire date'))
+ expire_date = models.DateTimeField(_('expire date'), db_index=True)
objects = SessionManager()
class Meta:
@@ -165,6 +165,24 @@ To return to the previous rendering (without the ability to clear the
model = Document
widgets = {'document': forms.FileInput}
+New index on database session table
+Prior to Django 1.3, the database table used by the database backend
+for the :doc:`sessions </topics/http/sessions>` app had no index on
+the ``expire_date`` column. As a result, date-based queries on the
+session table -- such as the query that is needed to purge old
+sessions -- would be very slow if there were lots of sessions.
+If you have an existing project that is using the database session
+backend, you don't have to do anything to accommodate this change.
+However, you may get a significant performance boost if you manually
+add the new index to the session table. The SQL that will add the
+index can be found by running the :djadmin:`sqlindexes` admin
+ python sqlindexes sessions
.. _deprecated-features-1.3:
Features deprecated in 1.3

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