🚀 go-pugleaf

>Does anybody knows if there is any available java class to manage
>indexed sequential files?

There is no standard java.io.* class to do this.
I have not heard of anyone writing one, but a search on Gamelan
may yield more info.

I bet it would be very simple to whisk up the basics of Indexed Sequential
Access using a hashtable to store the key/offset pairs, and keeping
that hashtable in a separate file which is read in at the start of
processing.   Use a random access file to store the data.

I might even have a go at whisking it up this weekend.
The basics would take less than an hour but all the corner cases
would probably take a couple of months.

      Peter

-- 
pvdl@best.com           Java Programmer's FAQ at:     http://www.afu.com 

Trying does not guarantee success, but not trying guarantees failure.
The trampoline that does not bend your brain is not the true trampoline.

Peter van der Linden wrote:
> >Does anybody knows if there is any available java class to manage
> >indexed sequential files?
> I have not heard of anyone writing one, but a search on Gamelan
> may yield more info.

  Actually, there's a book out in bookstores (entitled "Java
Algorithms", I think), that builds a basic indexed-sequential file
structure with a B-Tree and Serialization as the data format.  As
somebody who never gets a clear answer as to what data to store
initially, I LIKE THIS!

> I bet it would be very simple to whisk up the basics of Indexed
> Sequential Access using a hashtable to store the key/offset pairs, and 
> keeping that hashtable in a separate file which is read in at the
> start of processing.   Use a random access file to store the data.

  Umm...  Hashtables aren't an ordered storage, which would make the
sequential part difficult...

@>-`--,--
Chris Clark                         kitanin@hotmail.com
Compudata Systems Consulting, Inc.  compudat@cadvision.com
                                    ICQ#9342023

  "Now, I wonder who the deuce that could have been?"
		-Sherlock Holmes

Christopher Clark  <compudat@cadvision.com> wrote:
>  Actually, there's a book out in bookstores (entitled "Java
>Algorithms", I think), that builds a basic indexed-sequential file
>structure with a B-Tree and Serialization as the data format.  As
>somebody who never gets a clear answer as to what data to store
>initially, I LIKE THIS!


Thanks for the reference.

>  Umm...  Hashtables aren't an ordered storage, which would make the
>sequential part difficult...

Good point.   Maybe define an enumeration on the hastable as well.
Or -- if you restrict to fixed length records -- just read the file
using an input stream.

Peter van der Linden wrote:
> Christopher Clark  <compudat@cadvision.com> wrote:
> >  Umm...  Hashtables aren't an ordered storage, which would make the
> >sequential part difficult...
> Good point.   Maybe define an enumeration on the hastable as well.
> Or -- if you restrict to fixed length records -- just read the file
> using an input stream.

  AFAIK, an Enumeration on the Hashtable just returns them in hashcode
order.  Great as an "annoy client" and-or "pseudo-random" switch, but
not very practical.  OTOH, a JDK1.2 TreeMap works nicely, if a bit too
deep for index purposes.

  Personally, I'd extend what I saw in "Java Algorithms" to accept a
RandomAccessFile and a (1.2) Map.  Then, you can tailor your index to
you intended access.  (Mind you, I also like hitting myself in the head
with bricks...)

              LE    E.
It's just so F  X  L  .
                 IB    .  :-)

@>-`--,--
Chris Clark                         kitanin@hotmail.com
Compudata Systems Consulting, Inc.  compudat@cadvision.com
                                    ICQ#9342023

  "Now, I wonder who the deuce that could have been?"
		-Sherlock Holmes