dBase IV multiple index files?

dBase IV multiple index files?

Post by Alexandre Pechtchansk » Sun, 02 Aug 1992 01:34:49



=========================================================================
Hi, everybody:
I've heard a statement that seems pretty doubtful to me:
"... With .MDX files, all indexes are updated automatically, with
only one DOS File Handle, instead of one DOS File Handle for each index.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This frees up RAM and ... to make program more efficient (read faster)."
^^^^^^^^^^^^^^^^^                              ^^^^^^^^^^^^^^^^^^^^^^
I was always pretty sure that no matter what you do you have to allocate
one DOS file handle (either explicitly or implicitly) for each file you
access.  For dBase it spells one handle for each .DBF + one for each
.NDX etc.  The only way (IMHO) to circumvent it is to use one handle
for different files at different time, but it sure will lead to
_in_efficiency of program!
Can anybody confirm/disprove the above statement? (I mean the quoted
one, also all are welcome to spill flames on me for my apparent
stupidity ;-) )

    Thanks in advance
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Alex Pechtchanski, GCRC System Manager   voice: (212) 241-1804
Mount Sinai Medical Center, New York  -------------------------


-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

 
 
 

dBase IV multiple index files?

Post by Denis Beaurega » Mon, 03 Aug 1992 00:43:19



>=========================================================================
>Hi, everybody:
>I've heard a statement that seems pretty doubtful to me:
>"... With .MDX files, all indexes are updated automatically, with
>only one DOS File Handle, instead of one DOS File Handle for each index.
>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>This frees up RAM and ... to make program more efficient (read faster)."
>^^^^^^^^^^^^^^^^^                              ^^^^^^^^^^^^^^^^^^^^^^
>I was always pretty sure that no matter what you do you have to allocate
>one DOS file handle (either explicitly or implicitly) for each file you
>access.  For dBase it spells one handle for each .DBF + one for each
>.NDX etc.  The only way (IMHO) to circumvent it is to use one handle
>for different files at different time, but it sure will lead to
>_in_efficiency of program!
>Can anybody confirm/disprove the above statement? (I mean the quoted
>one, also all are welcome to spill flames on me for my apparent
>stupidity ;-) )

>    Thanks in advance
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>Alex Pechtchanski, GCRC System Manager   voice: (212) 241-1804
>Mount Sinai Medical Center, New York  |-------------------------


>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

I don't have a dBASE IV reference manual near me, but I can presume :-)
I suppose a .MDX file contains _many_ indexes, then if the time
to get position XXX inside a file is shorter that time to open a file,
then it will be faster (and this is likely).  Moreover, having many index
in one file means one handle for many index instead of one for each!
--

 /   \   Genealogiste officiel : Beauregard/Jarret/Jarest/Vincent
J   __>  Barthelemy Jarret (1471) -> Andre Jarret, sieur de Beauregard (1665)
\_.-===   -> Denis Beauregard (1992)                  Opinions ? Et pis non !

 
 
 

dBase IV multiple index files?

Post by Denis Beaurega » Mon, 03 Aug 1992 04:52:05



>=========================================================================
>Hi, everybody:
>I've heard a statement that seems pretty doubtful to me:
>"... With .MDX files, all indexes are updated automatically, with
>only one DOS File Handle, instead of one DOS File Handle for each index.
>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>This frees up RAM and ... to make program more efficient (read faster)."
>^^^^^^^^^^^^^^^^^                              ^^^^^^^^^^^^^^^^^^^^^^

I checked this in dBASE manual.  ONE .MDX file can contain up to 47
indexes corresponding each to one .NDX file.

Quote:>I was always pretty sure that no matter what you do you have to allocate
>one DOS file handle (either explicitly or implicitly) for each file you
>access.  For dBase it spells one handle for each .DBF + one for each

This is true.

Quote:>.NDX etc.  The only way (IMHO) to circumvent it is to use one handle

This is also true.

Quote:>for different files at different time, but it sure will lead to

This is false.  You could put many indexes in one file.

>Alex Pechtchanski, GCRC System Manager   voice: (212) 241-1804
>Mount Sinai Medical Center, New York  |-------------------------



--

 /   \   Genealogiste officiel : Beauregard/Jarret/Jarest/Vincent
J   __>  Barthelemy Jarret (1471) -> Andre Jarret, sieur de Beauregard (1665)
\_.-===   -> Denis Beauregard (1992)                  Opinions ? Et pis non !
 
 
 

1. Multiple indexes in dBase IV

Thanks to all who answered my question and helped me out of confusion.
-------

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Alex Pechtchanski, GCRC System Manager   Phone: (212) 241-1804
Mount Sinai Medical Center, New York  |-------------------------


-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

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