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This text describes some of the factors to consider when planning a large TURF run. This section was last updated on Sept 14,2006.
COMBINATION SIZE: the maximum combination size is 60 items. One could look at 16 out of 24, for example, or even 40 out of 45. However, 60 out of 210 is so large that it will never finish. This P-STAT command, PUT( COMBINATIONS(50,7))$ would return the number of combinations that 7 out of 50 would require, for example, and may be useful in estimating the time of a prospective run.
HOW LARGE A RUN CAN BE DONE: as described above, it depends on the number of cases, the number of combinations, the options used, and the speed of the PC itself.
If you are considering a large run, 10 billion combinations or more, you might try smaller run first, get it's time, and use the ratio of the combinations to estimate the time needed for the larger run.
IS 10 OUT OF 50 POSSIBLE: this is 10.27 billion combinations and would undoubtedly take quite a few hours, but is possible. The progress meter ticks every million combinations, so you can easily tell how long a run will take once it starts.
MEMORY CONSTRAINTS FOR INPUT: the input data must fit in memory. (We really don't want to read the data afresh from disk for each of 50 mil- lion different combinations.)
In most situations memory should not be a problem because the data is usually stored very compactly.
The final report shows how much of the input data area was used; that line however is omitted when less than 50% was needed.
MEMORY CONSTRAINTS FOR OUTPUT: the output files (except for the FULL.OUTPUT file) are collected in memory in sort order as the run progresses. The default sizes cause no problems.
If one asks for 20,000 results in the REACH.RESULTS or FREQ.RESULTS files, the run will be slightly slower but the file should fit.