TMG-L Archives

Archiver > TMG > 2004-06 > 1086758929

From: Dennis Lee Bieber <>
Subject: Re: [TMG] Wish list item
Date: Tue, 08 Jun 2004 22:28:49 -0700
References: <><><>
In-Reply-To: <>

On or about 06/08/04 21:03 a carrier pigeon from Jenny Joyce delivered:

>it still doesn't seem right that TMG is so fragile. Windows is going to
>crash from time to time. That's the way of the Microsoft world. But
>this shouldn't corrupt the TMG database.

At the roots, the "database" is also Microsoft -- Visual FoxPro.
TMG is just a GUI for accessing VFP data <G>.

VFP is sort of a Microsoft outgrowth of the old CP/M dBase
product, started from similar data files, with a Visual development
environment stuck on top. It supports larger databases then Microsoft's JET
engine (the actual database system used by Access -- Access is just a GUI
development/report generation tool that uses JET as the native engine). JET
is limited to ~2GB databases because all the data is stored within a single
file (including report, form, and VBA code). VFP uses individual files for
"fixed" records, varying text fields, and indices -- allowing any single
table to grow to ~2GB or so.

>Standard database technologies allow for journalling (no, that's not the
>same as incremental backups), so why can't TMG take advantage of this
>sort of technology. In it you still need to do regular backups. When a

I suspect that VFP doesn't support journalling, or even
transactions (There is a subtle difference, in my mind... "journalling"
maintains a log of changes which are later "merged" to the core data; this
means if the core data is corrupted, a backup and the journal can be used
to restore the interim transactions -- if the journal is corrupted, one
still has the core data in a pristine state. "transactions" tend to be of
more use for multiple access databases, in that they don't commit changes
to multiple records until all such changes have been defined).

MySQL 4.x is now available with a directly linked database engine,
so one wouldn't have to run a stand-alone server to use it. It does offer
transactions if using certain types of tables. It does not, at present,
enforce referential integrity (maybe the transactional tables do some of
this). It does not support stored procedures...

MaxDB by MySQL (aka SapDB 7.5) probably offers journalling, and
definitely does transactions. However, it probably requires an NT class OS
to run the database server.

The Microsoft Server Data Engine (MSDE -- the name seems to vary
by document <G>) is a subset of SQL Server 7, with limits on database size
and number of concurrent queries (it seems to have been meant to be used as
an SQL Server development environment, running on a coder's desktop -- came
with Visual Basic 6 Pro). It can be run on W9x. However... It, too, is a
client/server database engine and would be required to be running before
TMG could access the data.
> ============================================================ <
> | Wulfraed Dennis Lee Bieber KD6MOG <
> | Bestiaria Support Staff <
> ============================================================ <
> Home Page: <>; <

This thread: