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Updated Docs and bumped version

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Hopefully nearer 0.6
closes #368
This commit is contained in:
Ross Lawley
2011-12-02 08:14:25 -08:00
parent e9d7353294
commit 9bfc838029
4 changed files with 48 additions and 22 deletions
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47
docs/guide/querying.rst
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@@ -195,22 +195,6 @@ to be created::
>>> a.name == b.name and a.age == b.age
True
Dereferencing results
---------------------
When iterating the results of :class:`~mongoengine.ListField` or
:class:`~mongoengine.DictField` we automatically dereference any
:class:`~pymongo.dbref.DBRef` objects as efficiently as possible, reducing the
number the queries to mongo.
There are times when that efficiency is not enough, documents that have
:class:`~mongoengine.ReferenceField` objects or
:class:`~mongoengine.GenericReferenceField` objects at the top level are
expensive as the number of queries to MongoDB can quickly rise.
To limit the number of queries use
:func:`~mongoengine.queryset.QuerySet.select_related` which converts the
QuerySet to a list and dereferences as efficiently as possible.
Default Document queries
========================
By default, the objects :attr:`~mongoengine.Document.objects` attribute on a
@@ -313,8 +297,16 @@ would be generating "tag-clouds"::
from operator import itemgetter
top_tags = sorted(tag_freqs.items(), key=itemgetter(1), reverse=True)[:10]
Query efficiency and performance
================================
There are a couple of methods to improve efficiency when querying, reducing the
information returned by the query or efficient dereferencing .
Retrieving a subset of fields
=============================
-----------------------------
Sometimes a subset of fields on a :class:`~mongoengine.Document` is required,
and for efficiency only these should be retrieved from the database. This issue
is especially important for MongoDB, as fields may often be extremely large
@@ -347,6 +339,27 @@ will be given::
If you later need the missing fields, just call
:meth:`~mongoengine.Document.reload` on your document.
Getting related data
--------------------
When iterating the results of :class:`~mongoengine.ListField` or
:class:`~mongoengine.DictField` we automatically dereference any
:class:`~pymongo.dbref.DBRef` objects as efficiently as possible, reducing the
number the queries to mongo.
There are times when that efficiency is not enough, documents that have
:class:`~mongoengine.ReferenceField` objects or
:class:`~mongoengine.GenericReferenceField` objects at the top level are
expensive as the number of queries to MongoDB can quickly rise.
To limit the number of queries use
:func:`~mongoengine.queryset.QuerySet.select_related` which converts the
QuerySet to a list and dereferences as efficiently as possible. By default
:func:`~mongoengine.queryset.QuerySet.select_related` only dereferences any
references to the depth of 1 level. If you have more complicated documents and
want to dereference more of the object at once then increasing the :attr:`max_depth`
will dereference more levels of the document.
Advanced queries
================
Sometimes calling a :class:`~mongoengine.queryset.QuerySet` object with keyword