Hi Wim, This will be a quickie response... With newer versions of ncbi-blast there are 2 things that have made the process of splitting up the target databases so that your query can be multiplexed across multiple searches and machines far easier: o The "-z" option switch (used to be undocumented I think?) allows you to override/tell the blastall binary the effective size of the database. If you feed the original (large) value to the blastall binary while searching against the small slice you will at least get back the correct scores and statistics. This is a huge time and accuracy saver as trying to parse and adjust these values after the fact is a giant error-prone excercise in pain. o XML output of results Having the scores and statistics correct while getting the results back in a way that is far easier to parse than the human readable version is 95% of the battle. Everything else is fairly simple. -Chris Wim Glassee wrote: ><snip> > >I've noticed some people cut their databases and query sequences to >smaller pieces, with or without overlap, and perform separate blasts. >But how do you put them back together again? And are the results the >same? > >Wim > > > > -- Chris Dagdigian, <dag@sonsorol.org> Life Science IT & Research Computing Consultant Office: 617-666-6454, Mobile: 617-877-5498, Fax: 425-699-0193 Work: http://bioteam.net PGP KeyID: 83D4310E Yahoo IM: craffi