Opened 5 years ago

Closed 4 years ago

#20689 closed Bug (needsinfo)

Django 1.5.1: severe performance degradation on Oracle

Reported by: zakharov.vv@… Owned by: nobody
Component: Database layer (models, ORM) Version: 1.5
Severity: Normal Keywords: Oracle, cx_oracle, unicode
Cc: Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no


After migrating to Django 1.5.1, several queries takes thousands times more time comparing to Django 1.4.5.

Example query generated by ORM:

SELECT COUNT(*) FROM "TICKETS" WHERE ("TICKETS"."T_TYPE" IN (:arg0, :arg1, :arg2, :arg3) AND "TICKETS"."T_PARTNER_CODE" = :arg4 AND "TICKETS"."T_CHANEL" = :arg5 AND "TICKETS"."T_WORKER_CODE" = :arg6 AND "TICKETS"."T_CDATE" <= :arg7 AND "TICKETS"."T_CDATE" >= :arg8 )

Django 1.4.5: ~7ms
Django 1.5.1: ~193574ms (about 27000 times more!)

git bisect points to this commit: Indeed, forcing convert_unicode to be equal to force_bytes solves the issue.

The only found difference is in params to query:
Django 1.4.5:

[1, 38, 76, 92, '777-61', 61, 'pupkin', '2013-07-03 00:00:00', '2013-06-01 00:00:00']

Django 1.5.1:

[1, 38, 76, 92, u'777-61', 61, u'pupkin', u'2013-07-03 00:00:00', u'2013-06-01 00:00:00']

Django 1.5.1 hangs on this string (django/db/backends/oracle/

            return self.cursor.execute(query, self._param_generator(params))

Directly using cx_Oracle for this query shows no difference for two variants of query params.

Used versions:

  • cx-Oracle 5.1.2
  • instantclient (same for instantclient
  • Oracle Database 10g Enterprise Edition Release - 64bit Production

Change History (3)

comment:1 Changed 5 years ago by zakharov.vv@…

It seems, that issue affects only large tables. Table from example in description has about 100 million records. For small tables (thousands records) query time doesn't change after upgrading to 1.5.1.

comment:2 Changed 5 years ago by wim@…

Triage Stage: UnreviewedAccepted
Type: UncategorizedBug

Accepted. If you would like to contribute and would like to submit a patch (or even a pull request), you are welcome to do so!

comment:3 Changed 4 years ago by Shai Berger

Resolution: needsinfo
Status: newclosed


This ticket refers to versions of Django (1.5) and Oracle server (10g) which are no longer supported by their respective vendors, so I am closing it.

If the problem can be reproduced on newer versions (Oracle>=11 and Django>=1.7), please re-open.

(Although Django 1.7 nominally supports Oracle 10g, the core team has no access to an Oracle 10 server, which makes it very hard for us to solve problems against it).

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