psycopg

psycopg is a PostgreSQL database adapter for the Python programming language. Its main advantages are that it supports the full Python DBAPI 2.0 and it is thread safe at level 2.

psycopg was designed for heavily multi-threaded applications that create and destroy lots of cursors and make a conspicuous number of concurrent INSERTs or UPDATEs.

The psycopg distribution includes ZPsycopgDA, a Zope Database Adapter. This page is about psycopg 2, an almost complete rewrite of the psycopg 1.1.x branch.

Psycopg 2 features complete libpq v3 protocol COPY TO/COPY FROM and full object adaptation for all basic Python 2.3 types: strings (including unicode), ints, longs, floats, buffers (binary objects), booleans, mx.DateTime and builtin datetime types.

It also supports unicode queries and Python lists mapped to PostgreSQL arrays.

What is new in this release:

• This release features a bytea parser to make sure psycopg will work with binary data independently from libpq and PostgreSQL versions; support for non-normalized character encodings; a fix for empty queries; and better error reporting.

What is new in version 2.4 Beta 1:

• New features and changes
• Added register_composite() function to cast PostgreSQL composite types into Python tuples/namedtuples.
• More efficient iteration on named cursors.
• The build script refuses to guess values if pg_config is not found.
• Connections and cursors are weakly referenceable.
• Added 'b' and 't' mode to large objects: write can deal with both bytes strings and unicode; read can return either bytes strings or decoded unicode.
• COPY sends Unicode data to files implementing io.TextIOBase.
• The build script refuses to guess values if pg_config is not found.
• Improved PostgreSQL-Python encodings mapping. Added a few missing encodings: EUC_CN, EUC_JIS_2004, ISO885910, ISO885916, LATIN10, SHIFT_JIS_2004.
• Dropped repeated dictionary lookups with unicode query/parameters.
• Empty lists correctly roundtrip Python -> PostgreSQL -> Python.
• Bug fixes:
• Fixed adaptation of None in composite types (ticket #26). Bug report by Karsten Hilbert.
• Fixed several reference leaks in less common code paths.
• Fixed segfault when a large object is closed and its connection no more available.
• Added missing icon to ZPsycopgDA package, not available in Zope 2.12.9 (ticket #30). Bug report and patch by Pumukel.

What is new in version 2.3.2:

• release fixes a bug reported in 2.3.0 and 2.3.1 preventing Psycopg to connect to pgBouncer

What is new in version 2.3.0:

• This release introduces many new features like the support for the two-phase commit and notice paylod, an hstore to/from dict adapter, and query cancellation.
• It also drops support for libpq protocol 2, meaning that psycopg now works only with PostgreSQL 7.4 or higher on Python from 2.4 to 2.7.

What is new in version 2.3.0 Beta 1:

• This version introduces many new features related to PostgreSQL 9.0.
• psycopg now supports two-phase commit (TCP) as specified by the PEP-249, NOTIFY payloads, and the new hstore type.

What is new in version 2.2.2:

• This version fixes some errors related to exception propagation and improves support for timezones.

What is new in version 2.0.13:

• This release fixes a deadlock related to using the same connection from multiple threads.
• It also introduces support for UUID arrays.

What is new in version 2.0.9:

• This release adds better support for COPY FROM/COPY with quoted separators and unlimited query size, better handling of Inf and NaN float values, and support for UUID and Inet PostgreSQL.
• executemany() now returns the correct number of affected rows for multiple INSERT and UPDATE statements.

What is new in version 2.0.8:

• Some minor memory leaks were fixed.
• This release also adds a new get_backend_pid() method on the connection object and provides support for large objects.