#20414: Handling of numbers under oracle is slow
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Reporter: shai | Owner: shai
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: master
Severity: Normal | Keywords: oracle
Triage Stage: Unreviewed | performance
Easy pickings: 0 | Has patch: 1
| UI/UX: 0
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With current code, for all number columns, the Oracle backend asks
cx_Oracle to return the numbers as strings, and then transforms them back
to numbers on the way out. All this is done because Oracle supports higher
precision (and a wider range of integers) than the Python `float` type;
some values, if they are to be reported accurately, must be returned as
`decimal.Decimal`s, and cx_Oracle doesn't apparently do that on its own.
With cx_Oracle 5, though, it is possible to use a much better approach, on
a per-column (rather than per-row) basis, selecting the right output type
when there is enough information to do so, and making most of the
decisions once-per-query instead of once-per-row.
An original patch for this was written by Ian Kelly; I improved it and
made a pull-request in the stretch towards 1.5, but there was no ticket
for it and so it was never merged. I hope we can finally merge it into
1.6.
There was a little saga of discussions around this (mostly Anssi, Ian and
myself, https://groups.google.com/d/topic/django-
developers/4BNkJyGez9A/discussion). Some other issues are also mentioned
there. But this is the main one.
So now there is a ticket. Things changed, and the pull-request needed
updating. The new one is at https://github.com/django/django/pull/1071.
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Ticket URL: <https://code.djangoproject.com/ticket/20414>
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