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Fixed #28194 -- Added support for normalization and cover density to SearchRank.

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Hannes Ljungberg 2020-03-20 22:01:26 +01:00 • committed by Mariusz Felisiak
parent 4ed534758c
commit 0b51a4f894
4 changed files with 106 additions and 3 deletions
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28
docs/ref/contrib/postgres/search.txt
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@ -118,7 +118,7 @@ See :ref:`postgresql-fts-search-configuration` for an explanation of the
``SearchRank``
==============
.. class:: SearchRank(vector, query, weights=None)
.. class:: SearchRank(vector, query, weights=None, normalization=None, cover_density=False)
So far, we've returned the results for which any match between the vector and
the query are possible. It's likely you may wish to order the results by some
@ -137,6 +137,32 @@ order by relevancy::
See :ref:`postgresql-fts-weighting-queries` for an explanation of the
``weights`` parameter.
Set the ``cover_density`` parameter to ``True`` to enable the cover density
ranking, which means that the proximity of matching query terms is taken into
account.
Provide an integer to the ``normalization`` parameter to control rank
normalization. This integer is a bit mask, so you can combine multiple
behaviors::
>>> from django.db.models import Value
>>> Entry.objects.annotate(
... rank=SearchRank(
... vector,
... query,
... normalization=Value(2).bitor(Value(4)),
... )
... )
The PostgreSQL documentation has more details about `different rank
normalization options`_.
.. _different rank normalization options: https://www.postgresql.org/docs/current/textsearch-controls.html#TEXTSEARCH-RANKING
.. versionadded:: 3.1
The ``normalization`` and ``cover_density`` parameters were added.
``SearchHeadline``
==================