I have an app that reads a load of data from a DBISAM table or seven, then
does some analysis, and then outputs the results to different tables. In
the previous version, I managed to gain a lot of speed on the writes by
setting the Exclusive flag on the table.

In the new version, I'm going to be doing more than one analysis, and
using threads to speed them up. The results will all go into the same
final table. Since I have multiple writers, I can't therefore use
Exclusive.

I'd be interested to know therefore which people would think will be
faster:
1. Create temporary tables for each analysis, write them exclusive, and
then use an SQL update to "copy" the data from the temporary to the
master.
2. Just use normal writes to save them as they go, not using Exclusive at
all.
3. Something else I've not thought of.

Normal writes sort of worries me in that I might get the two threads bound
together and bogged down in competing for something. Temporary tables
looks like it might be more complicated, but also more predictable. Note
that memory tables aren't an option due to the volume of data. The data
will just be continuous writing once it starts (analysis could be some
minutes, followed by minutes of writing).

All thoughts welcome.

/Matthew Jones/

Matthew,

<< Normal writes sort of worries me in that I might get the two threads
bound together and bogged down in competing for something.  >>

That will never occur since the only time DBISAM accumulates record locks is
during a transaction, and transactions are serialized.

--
Tim Young
Elevate Software
www.elevatesoft.com

Okay, that sounds promising then - I think I'll try the dual writer one
first (option 2).

/Matthew Jones/