This sucks, Open office 2.3 spreadsheet cannot open or import text files that are larger than 65,536 rows. Basically, I need 100k rows. However, it is possible to recompile OO to extend rows limitation. From the OO wiki hack page:
Well, it depends on what your goal is. For personal use you may set MAXROWCOUNT_DEFINE in sc/inc/address.hxx to a different value, multiple of 128, and recompile the application respectively the libsc680*.so and shove it under your existing installation. However, doing so implies that you don't save to any binary file format like Excel or whatsoever, otherwise you risk loss of data. You'll also encounter drawing layer misfits in higher row numbers, may experience performance problems, and there may be other quirks lurking. Note that it generally works for data and formulas, but otherwise is completely untested.
For the number of columns the same applies to the MAXCOLCOUNT_DEFINE in sc/inc/address.hxx, just that the value must be a multiple of 16 instead.
I'm going to recompile my OO. Another good option is using MySQL. However, I'm not in mood to write a php / python scripts to just create graphs and other stuff.