mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-11-22 00:46:33 +03:00
PostgreSQL database adapter for the Python programming language
6cff5a3e08
This commit makes psycopg2 responsible for sending the status update (feedback) messages to the server regardless of whether a synchronous or asynchronous connection is used. Feedback is sent every *status_update* (default value is 10) seconds, which could be configured by passing a corresponding parameter to the `start_replication()` or `start_replication_expert()` methods. The actual feedback message is sent by the `pq_read_replication_message()` when the *status_update* timeout is reached. The default behavior of the `send_feedback()` method is changed. It doesn't send a feedback message on every call anymore but just updates internal structures. There is still a way to *force* sending a message if *force* or *reply* parameters are set. The new approach has certain advantages: 1. The client can simply call the `send_feedback()` for every processed message and the library will take care of not overwhelming the server. Actually, in the synchronous mode it is even mandatory to confirm every processed message. 2. The library tracks internally the pointer of the last received message which is not keepalive. If the client confirmed the last message and after that server sends only keepalives with increasing *wal_end*, the library can safely move forward *flush* position to the *wal_end* and later automatically report it to the server. Reporting of the *wal_end* received from keepalive messages is very important. Not doing so casing: 1. Excessive disk usage, because the replication slot prevents from WAL being cleaned up. 2. The smart and fast shutdown of the server could last indefinitely because walsender waits until the client report *flush* position equal to the *wal_end*. This implementation is only extending the existing API and therefore should not break any of the existing code. |
||
|---|---|---|
| doc | ||
| lib | ||
| psycopg | ||
| scripts | ||
| tests | ||
| .appveyor.yml | ||
| .gitignore | ||
| .travis.yml | ||
| AUTHORS | ||
| INSTALL | ||
| LICENSE | ||
| Makefile | ||
| MANIFEST.in | ||
| NEWS | ||
| psycopg2.cproj | ||
| README.rst | ||
| setup.cfg | ||
| setup.py | ||
| tox.ini | ||
psycopg2 - Python-PostgreSQL Database Adapter
=============================================
Psycopg is the most popular PostgreSQL database adapter for the Python
programming language. Its main features are the complete implementation of
the Python DB API 2.0 specification and the thread safety (several threads can
share the same connection). It was designed for heavily multi-threaded
applications that create and destroy lots of cursors and make a large number
of concurrent "INSERT"s or "UPDATE"s.
Psycopg 2 is mostly implemented in C as a libpq wrapper, resulting in being
both efficient and secure. It features client-side and server-side cursors,
asynchronous communication and notifications, "COPY TO/COPY FROM" support.
Many Python types are supported out-of-the-box and adapted to matching
PostgreSQL data types; adaptation can be extended and customized thanks to a
flexible objects adaptation system.
Psycopg 2 is both Unicode and Python 3 friendly.
Documentation
-------------
Documentation is included in the ``doc`` directory and is `available online`__.
.. __: http://initd.org/psycopg/docs/
For any other resource (source code repository, bug tracker, mailing list)
please check the `project homepage`__.
Installation
------------
Building Psycopg requires a few prerequisites (a C compiler, some development
packages): please check the install_ and the faq_ documents in the ``doc`` dir
or online for the details.
If prerequisites are met, you can install psycopg like any other Python
package, using ``pip`` to download it from PyPI_::
$ pip install psycopg2
or using ``setup.py`` if you have downloaded the source package locally::
$ python setup.py build
$ sudo python setup.py install
You can also obtain a stand-alone package, not requiring a compiler or
external libraries, by installing the `psycopg2-binary`_ package from PyPI::
$ pip install psycopg2-binary
The binary package is a practical choice for development and testing but in
production it is advised to use the package built from sources.
.. _PyPI: https://pypi.org/project/psycopg2/
.. _psycopg2-binary: https://pypi.org/project/psycopg2-binary/
.. _install: http://initd.org/psycopg/docs/install.html#install-from-source
.. _faq: http://initd.org/psycopg/docs/faq.html#faq-compile
.. __: http://initd.org/psycopg/
:Linux/OSX: |travis|
:Windows: |appveyor|
.. |travis| image:: https://travis-ci.org/psycopg/psycopg2.svg?branch=master
:target: https://travis-ci.org/psycopg/psycopg2
:alt: Linux and OSX build status
.. |appveyor| image:: https://ci.appveyor.com/api/projects/status/github/psycopg/psycopg2?branch=master&svg=true
:target: https://ci.appveyor.com/project/psycopg/psycopg2/branch/master
:alt: Windows build status