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[j773303]

The data file size is 500,0000 raws, How to truncate to 400,0000 raws? I wish to delete
from 1 raw to 100,0000 raws, which command can do this?

[Rajeev Shukla · Accepted solution]

Have a look at man pages of "split" command
That will solve your purpose

[j773303]

Coulu you please tell me a sample about how split usage? Thanks!

[Rajeev Shukla]

I am sorry i realised later that you are talking about datafiles. Split actually does in bytes i.e in different sizes of files, i couldn't get it going with split.
and do raws means rows and the files are database files like oracle, the only way you could do is write a sql statement to drop the rows
Otherwise there is nothing you can do with datafiles than writing a c program, dearing the lines and use truncate() function

[T G Manikandan]

Please explain what u need

[Michael Schulte zur Sur]

Hi,

tail -400000 datfile > newdatafile
is that, what you where looking for?

Michael

[Massimo Bianchi]

if you are talking about a oracle database table:


delete from schema.table where rownum < 400.000;

This can take much to complete.

if you are talking about an ascii file:

split -l 100000 yourfilename splitted_filename

will generate 5 file, named splitted_filename.xaa .xab .xac

keep the last, should be splitted_filename.xae, rename it as your original file and you have done it.

Massimo