====================== Announcing bcolz 0.9.0 ======================
What's new ==========
This is mostly a smallish feature and bugfix release. One large topic was implementing 'addcol' and 'delcol' to properly handle on-disk tables. 'addcol' now has a new keyword argument 'move' that allows you to specify if you want to move or copy the data. 'delcol' has a new keyword argument 'keep' which allows you preserve the data on disk when removing a column. Additionally, ctable now supports an 'auto_flush' keyword that makes it flush to disk automatically after any methods that may write data.
Another important aspect is handling the GIL. In this release, we do keep the GIL while calling Blosc compress and decompress in order to support lock-free operation of newer Blosc versions (1.5.x and beyond) that no longer have a global state.
Furthermore we now distribute the 'carray_ext.pxd' as part of the package via PyPi to ease building applications on bcolz, for example *bquery*.
Finally, the Sphinx based API documentation is now autogenerated from the docstrings in the Python sources.
For the full list, please check the release notes at:
What it is ==========
*bcolz* provides columnar and compressed data containers that can live either on-disk or in-memory. Column storage allows for efficiently querying tables with a large number of columns. It also allows for cheap addition and removal of column. In addition, bcolz objects are compressed by default for reducing memory/disk I/O needs. The compression process is carried out internally by Blosc, an extremely fast meta-compressor that is optimized for binary data. Lastly, high-performance iterators (like ``iter()``, ``where()``) for querying the objects are provided.
bcolz can use numexpr internally so as to accelerate many vector and query operations (although it can use pure NumPy for doing so too). numexpr optimizes the memory usage and use several cores for doing the computations, so it is blazing fast. Moreover, since the carray/ctable containers can be disk-based, and it is possible to use them for seamlessly performing out-of-memory computations.
bcolz has minimal dependencies (NumPy), comes with an exhaustive test suite and fully supports both 32-bit and 64-bit platforms. Also, it is typically tested on both UNIX and Windows operating systems.
Together, bcolz and the Blosc compressor, are finally fulfilling the promise of accelerating memory I/O, at least for some real scenarios:
Other users of bcolz are Visualfabriq (http://www.visualfabriq.com/) the Blaze project (http://blaze.pydata.org/), Quantopian (https://www.quantopian.com/) and Scikit-Allel (https://github.com/cggh/scikit-allel) which you can read more about by pointing your browser at the links below.
* *bquery*, A query and aggregation framework for Bcolz: * https://github.com/visualfabriq/bquery
* Notebooks showing Blaze + Pandas + BColz interaction: * http://nbviewer.ipython.org/url/blaze.pydata.org/notebooks/timings-csv.ipynb * http://nbviewer.ipython.org/url/blaze.pydata.org/notebooks/timings-bcolz.ipy...
* Using compressed data containers for faster backtesting at scale: * https://quantopian.github.io/talks/NeedForSpeed/slides.html
* Provides an alternative backend to work with compressed arrays * https://scikit-allel.readthedocs.org/en/latest/bcolz.html
bcolz is in the PyPI repository, so installing it is easy::
$ pip install -U bcolz
Visit the main bcolz site repository at: http://github.com/Blosc/bcolz
Home of Blosc compressor: http://blosc.org
User's mail list: firstname.lastname@example.org http://groups.google.com/group/bcolz
License is the new BSD: https://github.com/Blosc/bcolz/blob/master/LICENSES/BCOLZ.txt
Release notes can be found in the Git repository: https://github.com/Blosc/bcolz/blob/master/RELEASE_NOTES.rst