A Monday 13 December 2010 14:56:26 Dominik Szczerba escrigué: > > But, for knowing if accessing columns this is efficient for your > > case, I'd need more info on your datasets. Are they contiguous or > > chunked? If chunked, which is the chunkshape you have chosen? > > Both. Files saved from matlab are uncompressed/contiguous, the ones > saved from my program are usually compressed/chunked and the size is > around 1024^2/sizeof(type).
Well, for PyTables (or any C application) and contiguous datasets, accessing data by columns is inefficient: the privileged direction for performance are rows. For the chunked datasets, you only provided the chunksize of one of the dimensions, which I assume is the last one, so again, this will be inefficient for a C-based app. Hope this helps, -- Francesc Alted ------------------------------------------------------------------------------ Oracle to DB2 Conversion Guide: Learn learn about native support for PL/SQL, new data types, scalar functions, improved concurrency, built-in packages, OCI, SQL*Plus, data movement tools, best practices and more. http://p.sf.net/sfu/oracle-sfdev2dev _______________________________________________ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
