Metadata-Version: 2.0
Name: nplusone
Version: 0.2.1
Summary: Detecting the n+1 queries problem in Python
Home-page: https://github.com/jmcarp/nplusone
Author: Joshua Carp
Author-email: jm.carp@gmail.com
License: Copyright 2015 Joshua Carp
Requires-Dist: six (>=1.9.0)
Requires-Dist: blinker (>=1.3)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

Description: ========
        nplusone
        ========
        
        .. image:: https://img.shields.io/pypi/v/nplusone.svg
            :target: http://badge.fury.io/py/nplusone
            :alt: Latest version
        
        .. image:: https://img.shields.io/travis/jmcarp/nplusone/master.svg
            :target: https://travis-ci.org/jmcarp/nplusone
            :alt: Travis-CI
        
        .. image:: https://img.shields.io/codecov/c/github/jmcarp/nplusone/master.svg
            :target: https://codecov.io/github/jmcarp/nplusone
            :alt: Code coverage
        
        nplusone is a library for detecting the n+1 queries problem in Python ORMs, including SQLAlchemy, Peewee, and the Django ORM.
        
        The Problem
        ===========
        
        Many object-relational mapping (ORM) libraries default to lazy loading for relationships. This pattern can be efficient when related rows are rarely accessed, but quickly becomes inefficient as relationships are accessed more frequently. In these cases, loading related rows eagerly using a ``JOIN`` can be vastly more performant. Unfortunately, understanding when to use lazy versus eager loading can be challenging: you might not notice the problem until your app has slowed to a crawl.
        
        ``nplusone`` is an ORM profiling tool to help diagnose and improve poor performance caused by inappropriate lazy loading. ``nplusone`` monitors applications using Django or SQLAlchemy and sends warnings when potentially expensive lazy loads are emitted. It can identify the offending relationship attribute and specific lines of code behind the problem, and recommend fixes for better performance.
        
        ``nplusone`` also detects inappropriate eager loading for Flask-SQLAlchemy and the Django ORM, emitting a warning when related data are eagerly loaded but never accessed within the current request.
        
        Installation
        ============
        
        ::
        
            pip install -U nplusone
        
        nplusone supports Python >= 2.7 or >= 3.3.
        
        Usage
        =====
        
        Note: ``nplusone`` should only be used for development and should not be deployed to production environments.
        
        Django
        ******
        
        Note: ``nplusone`` supports Django 1.7 and 1.8.
        
        Add ``nplusone`` to ``INSTALLED_APPS``: ::
        
            INSTALLED_APPS = (
                ...
                'nplusone.ext.django',
            )
        
        Add ``NPlusOneMiddleware``: ::
        
            MIDDLEWARE_CLASSES = (
                ...
                'nplusone.ext.django.NPlusOneMiddleware',
            )
        
        Optionally configure logging settings: ::
        
            NPLUSONE_LOGGER = logging.getLogger('nplusone')
            NPLUSONE_LOG_LEVEL = logging.WARN
        
        Configure logging handlers: ::
        
            LOGGING = {
                'version': 1,
                'handlers': {
                    'console': {
                        'class': 'logging.StreamHandler',
                    },
                },
                'loggers': {
                    'nplusone': {
                        'handlers': ['console'],
                        'level': 'WARN',
                    },
                },
            }
        
        When your app loads data lazily, ``nplusone`` will emit a warning: ::
        
            Potential n+1 query detected on `<model>.<field>`
        
        Consider using `select_related <https://docs.djangoproject.com/en/1.8/ref/models/querysets/#select-related>`_ or `prefetch_related <https://docs.djangoproject.com/en/1.8/ref/models/querysets/#prefetch-related>`_ in this case.
        
        When your app eagerly loads related data without accessing it, ``nplusone`` will log a warning: ::
        
            Potential unnecessary eager load detected on `<model>.<field>`
        
        Flask-SQLAlchemy
        ****************
        
        Wrap application with ``NPlusOne``: ::
        
            from flask import Flask
            from nplusone.ext.flask_sqlalchemy import NPlusOne
        
            app = Flask(__name__)
            NPlusOne(app)
        
        Optionally configure logging settings: ::
        
            app = Flask(__name__)
            app.config['NPLUSONE_LOGGER'] = logging.getLogger('app.nplusone')
            app.config['NPLUSONE_LOG_LEVEL'] = logging.ERROR
            NPlusOne(app)
        
        When your app loads data lazily, ``nplusone`` will emit a warning: ::
        
            Potential n+1 query detected on `<model>.<field>`
        
        Consider using ``subqueryload`` or ``joinedload`` in this case; see SQLAlchemy's guide to `relationship loading <http://docs.sqlalchemy.org/en/latest/orm/loading_relationships.html>`_ for complete documentation.
        
        When your app eagerly loads related data without accessing it, ``nplusone`` will log a warning: ::
        
            Potential unnecessary eager load detected on `<model>.<field>`
        
        Ignoring Warnings
        *****************
        
        To suppress warnings thrown by intentional lazy loading, use the ``ignore`` context manager: ::
        
            from nplusone.core import signals
        
            with signals.ignore(signals.lazy_load):
                # lazy-load rows
                # ...
        
        License
        =======
        
        MIT licensed. See the bundled `LICENSE <https://github.com/jmcarp/nplusone/blob/master/LICENSE>`_ file for more details.
        
Keywords: nplusone
Platform: UNKNOWN
Classifier: Development Status :: 2 - Pre-Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Natural Language :: English
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
