Fast file data retrieval?

[MRAB]

On 12/03/2012 19:39, Virgil Stokes wrote:
> I have a rather large ASCII file that is structured as follows
>
> header line
> 9 nonblank lines with alphanumeric data
> header line
> 9 nonblank lines with alphanumeric data
> ...
> ...
> ...
> header line
> 9 nonblank lines with alphanumeric data
> EOF
>
> where, a data set contains 10 lines (header + 9 nonblank) and there can
> be several thousand
> data sets in a single file. In addition,*each header has a* *unique ID
> code*.
>
> Is there a fast method for the retrieval of a data set from this large
> file given its ID code?
>
Probably the best solution is to put it into a database. Have a look at
the sqlite3 module.

Alternatively, you could scan the file, recording the ID and the file
offset in a dict so that, given an ID, you can seek directly to that
file position.