developer toolbox » harbour

NTX je puno brži ?

http://www.mail-archive.com/harbour@harbour-project.org/msg25415.html

> I don't know the effectiveness of the DBFNTX in Harbour, so i ask you
>  if also the A) choice is dangerous and the pure Harbour path is the only
> affordable.

In Harbour DBFNTX is probably *much faster* then in Clipper and for sure
they can be used to index realy big tables (I know that some people
use Harbour only to reindex files for Clipper due to huge speed differnce
and the fact that over some size limits Clipper begins to GPF during
indexing). Harbour DBFNTX implementation also supports all CDX extensions
and few others but you will not be able to enable all of them if you want
to share data with Clipper.  *Compound index*, large NTX file support up to
4TB or using RECNO as hidden part of index key to eliminate linear scan
during record updating in indexes uses keys with big number of repeated
values are extensions which change index formats and I implemented them
only in Harbour and xHarbour so only in these languages can operate on
such NTX indexes.
Technically NTX format is much faster then CDX. In the ideal environment
where you have a lot of RAM and you can keep index files in memory CDX
is many times slower then NTX. But we are not leaving in ideal world and
in most of cases indexes are accessed using slow network connections.
It means that the size of index files will determinate the speed. CDX
files store keys in leaf nodes in compressed form what greatly reduces
the total index size and it's the reason of better overall performance
when the cost of reading/writing from/to index file is very big, i.e.
files are stored on file server.

best regards,
Przemek

Technically NTX format is much faster then CDX. In the ideal environment where you have a lot of RAM and you can keep index files in memory CDX is many times slower then NTX.

indexes are accessed using slow network connections. It means that the size of index files will determinate the speed.

u F18 ne koristi se mrežni pristup tako da ovo nije problem, prebacio sam F18 na DBFNTX engine