On Saturday, Sep 13, 2003, at 05:52 US/Pacific, Sara wrote: [..]
2. I have DB with 4-8 digits number in each line e.g.[..]
1238483 92933 09983433 093
The truncate function truncates the file very abruptly
well actually there are various types of DB's - some such as SDBM_File will have 'information' at the start of the 'block of data' that points to where the actual data resides from the bottom of the block up - leaving a potential 'space' in the middle of the data block.
What it sounds like you want is a 'compact' or 'purge' function that will 're-write' the data into a new DB file. Essentially the same issue that you ran into with wanting to keep only the first "N-Blocks" of data from the file.
Since only 'you' know how the internals of the DB are laid out, you will need to resolve what data in it is still good, and which data in it is 'dead wood' that needs to be purged.
One trick to think about is
move DB_File to OLD_DB_file
create TMP_DB_FILE
traverse OLD_DB_FILE and write to TMP_DB_FILE
move TMP_DB_FILE to DB_FILEciao drieux
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