ted@imsvax.UUCP (Ted Holden) (01/12/87)
Aside from using index files rather than B-trees (which would seem to make Dbase slow on large multi-user applications), the last opinions I was getting on the multi-user versions of DbaseIII six months ago or so was that it simply had too many problems to consider using. I would appreciate hearing from anyone with any more recent experience with multi-user versions of Dbase as to whether there are believable versions of it out now or whether the situation is substantially the same as it was. Ted Holden IMS
sns@tybalt.caltech.edu (Samuel N. Southard) (01/12/87)
I am required to manage/keep running a multi-user DbaseIII+ sytem using PC/AT's over Ethernet using Ungerman Bass cards. The network is easy to use, but Dbase III is inredibly slow, even with a single-user version. As far as Dbase III+ over the network goes, it is about as good as Dbase III for a single user. However, if you are doing any serious database work, I would reccommend something else (I don't know what). As a speed reference, it takes 45-60 min. to index 6500 names, and takes over 90 min. to process this same file for labels. The records are only 400 bytes each. If you like Dbase III already, however, you lose almost no functionality from Dbase III (I haven't found any yet, but just to be safe....). Of course there are some things you can't do when multiple people are accessing the database, but they are things like re-structuring the database, which is perfectly reasonable. Also, there are a couple extra commands that you have to use, such as locking the file so you can edit, but these are also perfectly reasonable. Small gripe: I haven't yet found a way to make the default so that multiple people can access the same database. In summary, if you like single-user Dbase III, you will like multi- user Dbase III; if you are sane, you won't like either. Sam Southard, Jr. sns@tybalt.caltech.edu.UUCP
brian@prism.UUCP (01/13/87)
One DBIII / network installation that I am aware or uses an 8mhz pc-at
as a dedicated server (core 72 megabyte hard disk)
with Novell's netware and 3com hardware; The installation runs dbaseIII
nearly exclusively on everything from compaq portables with no hard disk
(but network card) to compaq 286 portables with 2 hard disks. Anyway, they
are managing nearly 15000 records of nearly 500 bytes each, with 3 index
files. All of the workstations (up to 6 at a time) access the common
database, and the dbase programs were written to take care of record locking
and the like.
The operation works as follows:
partially completed records are added into the main database.
at some later time, these blank records are retrieved based upon two fields
of information as the key (referencing yet another file to get one of the
keys), and the additional information is entered. The retrieval and addition
of data must be fast, since it is done while a person is on the phone.
The system performance has been pretty good:
Record retrieval happens on a 4.77 mhz compaq for a typical record in under 4
seconds. (one other user on the system)
The information is changed (using a non-dbase program, I might add, since
DBIII is atrociously slow at checking key inputs in a loop) as fast as the
typist can go, and the record is replaced in the database. Since a duplicate
of the transaction is kept for later processing, the actual time before
another record can be changed can take up to 20 seconds longer.
For their application, this system works quite nicely.
Oh, packing and re-indexing the database (remember, all three indices, 15K
records) done once a day (since everyone else must be logged off) takes
under 10 minutes.
It should not be taking as long to pack and reindex your database, unless
your server or its hard disk is really slow...
Brian K. Moran
----
Brian K. Moran brian@mirror.TMC.COM
{mit-eddie, ihnp4!inmet, wjh12, cca, datacube}!mirror!brian
Mirror Systems 2067 Massachusetts Avenue Cambridge, MA, 02140
Telephone: 617-661-0777 extension 141
"Won't somebody tell me, just who and what I did...
Why's this ring on my finger, and who's that screaming kid? "
From "Lost Weekend" by the Beat Farmers
---