The Free Text index files are optimized for speed in building, browsing and retrieving, and they are fairly space-efficient too. Every distinct word in your input database file requires 32 bytes in the Free Text keys file, and each occurrence of a word uses four bytes in the Free Text pointers file. Thus, for small files where there are many different words, the .k and .p files often add up to 150% or so of the size of the main file. But as files get larger, efficiency increases since there are fewer new words showing up per megabyte. In my experience, for files in the 5-50 MB range, the index structures add about 80% overhead to the original file. That's pretty good compared to many other database systems.
During Free Text index-building, you need to have room on your disk for a couple of extra copies of your original database file. That space is used to hold temporary partial index files which are automatically erased when indexing is finished. If you try to build an index without having enough free space on your disk to hold the temporary files, you are likely to have a system crash! (You should never lose any data, however ΓÇö I never have, and have received no reports of data loss ΓÇö but see the section IN CASE OF TROUBLE for information on how to recover.)
