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From: aoki@postgres.Berkeley.EDU (Paul M. Aoki)
To: postgres@postgres.Berkeley.EDU
Subject: [fmg@trillium.com: Inversion Files...]
Date: Tue, 25 Jan 94 13:07:10 -0800
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------- Forwarded Message

> From:  fmg@trillium.com
> To:  postgres@postgres.Berkeley.EDU
> Subject:  Inversion Files...
> Date:  Tue, 25 Jan 1994 09:51:41 +0800
>
> I have some conceptual questions about the Inversion Filesystem.
> 
> If I set up a class that has a Inversion file as an attribute ala
> 
> create File 
> (
>    name = text,
>    ifile = InvFile
> ) \g
> 
> My I/O functions inv_file_in and inv_file_out do the following
> 
> inv_file_in 
>    Check for inversion file's existance with LOstat();
>    If it doesn't exist: 
>       LOcreat(fName, INV_READ|INV_WRITE|INV_ARCHIVE, Inversion).
>       read from a unix file, write to the inversion file.
>       close both files.
>       Fill my IFile struct (varlena) and return.
>    If it does exist, fill my IFile struct (varlena), and return;
> 
> inv_file_out
>    return the name component of my IFile struct
> 
> 
> I also defined a function inv_file_eq() which compares the names of
> two files for equality.
> 
> Now, some questions...
> 
>    When I append new touples to the table, a new inversion file
>    is created on the system. I can see these files with 
>    $POSTGRESHOME/bin/pls. I added the LOstat call to inv_file_in
>    because it is called when I test for equality, and I can't recreate
>    the file (nor would I want to). Is this reasonable?
> 
>    Next, I can do historical queries on this table, and see all versions
>    of the table over time as I append and replace touples. Now, how do
>    I retrieve an old version of the actual inversion file itself rather
>    than its representation in the table which is merely its name, and may
>    be the same at different time though the contents may be different.
> 
>    How do I do the same thing from libpq?
> 
>    I'd also be interested to hear how people who have used the inversion
>    file system have set up their tables and input/output routines to support
>    their conceptual models...
> 
>    Perhaps I'm just confused about how Inversion file are supposed to be used
?
> 
> 
>    Thanks,
>    Frank
> +--------------------------------------+-------------------------------------
-+
> |Frank M. Goodman                      |         Trillium Digital Systems Inc
.|
> |f_goodman@trillium.com                |       2001 S. Barrington Ave, Ste 21
5| 
> |Ph: 310 479-0500, Fax: 310 575-0172   |         Los Angeles, California 9002
5|
> +--------------------------------------+-------------------------------------
-+

------- End of Forwarded Message
--
  Paul M. Aoki  |  CS Div., Dept. of EECS, UCB  |  aoki@postgres.Berkeley.EDU
                |  Berkeley, CA 94720           |  ...!uunet!ucbvax!aoki