A Sunday 05 December 2010 18:14:23 Gerrit Holl escrigué: > Hi, > > I have a table with 1.242.619.562 rows of 142 bytes each (I know I > would benefit from PyTables Pro). Because I didn't know the number of > rows when I generated it, I used ptrepack after finishing creating > the table, expecting this to increase readout speed considerably. To > my surprise, the chunkshape before and after were the same (7384,). > Does this mean my chunkshape was already optimal? But I didn't > provide any estimate for the number of rows... "When the table or > array size is larger than, say 100MB, you are strongly suggested to > provide such a guess; failing to do that may cause your application > to do very slow I/O operations and to demand huge amounts of > memory."; is this always the case, or did my table just happen to > have an optimal chunkshape more or less by accident?
No, the 'optimal' chunksize is not re-computed by default (because, in general, you may want to keep your own fine-tuned settings). For allowing ptrepack to find a new optimal value, please use the ``-- chunkshape="auto"`` flag when using ptrepack. Hope this helps, -- Francesc Alted ------------------------------------------------------------------------------ What happens now with your Lotus Notes apps - do you make another costly upgrade, or settle for being marooned without product support? Time to move off Lotus Notes and onto the cloud with Force.com, apps are easier to build, use, and manage than apps on traditional platforms. Sign up for the Lotus Notes Migration Kit to learn more. http://p.sf.net/sfu/salesforce-d2d _______________________________________________ Pytables-users mailing list Pytables-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pytables-users
