Hi Anthony and Antonio, Thanks for your fast responses. It's great to hear all features are now free to use, though I needed one and a half week to get this.
The first reference I read to learn the usage of PyTables was Hints for SQL Users [1], where is stated several times, for example in the section ' Creating an index': > Indexing is supported in the commercial version of PyTables (PyTablesPro). I would suggest that these texts should be updated. Being convinced it's only available in Pro-Version after I read it so often, I also overread the warning in the PyTables Pro page[2] (As I were only interested in the features not available in the free version I just scrolled down immediately, diagonal reading...). So the next suggestion is to give a color to the warning text there :) [1] http://www.pytables.org/moin/HintsForSQLUsers#Creatinganindex http://www.pytables.org/moin/HintsForSQLUsers#Selectingdata [2] http://www.pytables.org/moin/PyTablesPro regards, Sebastian On Mon, Jun 24, 2013 at 4:25 AM, Wagner Sebastian < sebastian.wagner...@ait.ac.at> wrote: > Dear PyTables-Users,**** > > ** ** > > For testing purposes I use a PyTables DB with 4 columns (1x Uint8 and > 3xFloat) with 750k rows, the total file size about 90MB. As the free > version does no support indexing I thought that a search (full-table) > on this database would last a least one or two seconds, because the > file has to be loaded first (throttleneck I/O), and then the search > over ~20k rows can begin. But PyTables took only 0.05 seconds for a > full table search (in-kernel, so near C-speed, but nevertheless full > table), while my bisecting algorithm with a precomputed sorted list > wrapped around PyTables (but saved in there), took about 0.5 > seconds.**** > > ** ** > > So the thing I don?t understand: How can PyTables be so fast without > any Indexing? > Hi Sebastian, First, there is no longer a non-free version of PyTables and v3.0 *does* have indexing capabilities. However, you have to enable them so you probably weren't using them. PyTables is fast because HDF5 is a binary format, it using pthreads under the covers to parallelize some tasks, and it uses numexpr (which is also parallel) to evaluate many expressions. All of these things help make PyTables great! Be Well Anthony Il 24/06/2013 11:25, Wagner Sebastian ha scritto: > Dear PyTables-Users, > > For testing purposes I use a PyTables DB with 4 columns (1x Uint8 and > 3xFloat) with 750k rows, the total file size about 90MB. As the free version > does no support indexing I thought that a search (full-table) on this > database would last a least one or two seconds, because the file has to be > loaded first (throttleneck I/O), and then the search over ~20k rows can > begin. But PyTables took only 0.05 seconds for a full table search > (in-kernel, so near C-speed, but nevertheless full table), while my bisecting > algorithm with a precomputed sorted list wrapped around PyTables (but saved > in there), took about 0.5 seconds. > > So the thing I don't understand: How can PyTables be so fast without any > Indexing? > > I'm using 3.0.0rc2 coming with WinPython > > Regards, > Sebastian The indexing features of PyTables Pro are now available in the open source version of PyTables since version 2.3 (please see [1]). [1] http://pytables.github.io/release-notes/RELEASE_NOTES_v2.3.x.html#changes-from-2-2-1-to-2-3 ciao -- Antonio Valentino ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
