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Diffstat (limited to 'docs/ref/databases.txt')
| -rw-r--r-- | docs/ref/databases.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/docs/ref/databases.txt b/docs/ref/databases.txt index 51feceea04..16addc52bc 100644 --- a/docs/ref/databases.txt +++ b/docs/ref/databases.txt @@ -171,6 +171,24 @@ If you need to add a PostgreSQL extension (like ``hstore``, ``postgis``, etc.) using a migration, use the :class:`~django.contrib.postgres.operations.CreateExtension` operation. +.. _postgresql-server-side-cursors: + +Server-side cursors +------------------- + +.. versionadded:: 1.11 + +When using :meth:`QuerySet.iterator() +<django.db.models.query.QuerySet.iterator>`, Django opens a :ref:`server-side +cursor <psycopg2:server-side-cursors>`. By default, PostgreSQL assumes that +only the first 10% of the results of cursor queries will be fetched. The query +planner spends less time planning the query and starts returning results +faster, but this could diminish performance if more than 10% of the results are +retrieved. PostgreSQL's assumptions on the number of rows retrieved for a +cursor query is controlled with the `cursor_tuple_fraction`_ option. + +.. _cursor_tuple_fraction: https://www.postgresql.org/docs/current/static/runtime-config-query.html#GUC-CURSOR-TUPLE-FRACTION + Test database templates ----------------------- |