write a 20GB file

[Nobody]

On Fri, 14 May 2010 18:38:55 -0400, J wrote:

>>> someone smarter than me can correct me, but file.write() will write when
>>> it's buffer is filled, or close() or flush() are called.
>>
>> And, in all probability, seek() will either flush it immediately or cause
>> the next write() to flush it before writing anything.
> 
> Ahhh... I didn't know that... I thought seek() just moved the pointer
> through the file a little further....

Think about how this affects buffering. write() writes at the current file
position. If you write, then seek, then write, it can't just concatenate
the two sets of data, as that would "lose" the seek.

Either the buffer has to contain multiple, distinct sets of data, each
with an associated position, or (far more likely), the original data must
be written to the correct location before the second set of data can be
stored.