You can get database corruption in any database.
You get db corruption from something not finishing as expected quite often
caused from hardware problems, power spikes, or user interuption.
Example when you add a new row to a table, there are a few things that have
to happen, and if they don't all happen, you wind up with some type of
corruption. I may not have the steps in the correct order here, but this is
what has to happen to insert a new row.
1. need to check the #1 file to get the address of the last row in the #2
file.
2. check the #2 file and see if there is enough space for the new row.
If there is not enough space, get a block of space from the OS and add it
to the #2 file.
3. put the row in the #2 file
4. assign the previous row pointer to the previous row in the table, set the
next row pointer to 0
5. update the next row pointer in the previous row to the new row.
6. update the #1 file last row pointer and add 1 to the row count.
7. update all of the indexes in the #3 for the table with the new row.
Now if something happens to interrupt these steps, then the files will be
out of sync and strange things will start happening.
Products like Oracle and SQL server are less likely to have problems because
the entire process for manipulating the database is done on the server. In
products like R:base and Access the workstation is updating the pointers on
the db on the server. There are more points of potential failure. Also on
the higher end products like Oracle and SQL Server, every transaction is
also logged to a seperate database, so if corruption is discovered, it has a
log file and can recover from a previously know good point and re enter all
of the tranactions.
If you get data corruption on a regular basis, then there is probably
something wrong on your network. UPSs on every workstation, server, and hub
really help things. A lot of offices have overloaded circuits and you get
small brown outs and computers have a tendancy to drop packets, but don't
re-boot. Small UPSs on the workstations take care of this.
Troy
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Victor
Timmons
Sent: Friday, June 20, 2003 10:47 AM
To: RBASE-L Mailing List
Subject: [RBASE-L] - Database corruption questions??
This is not meant in a bad way. I am not criticizing R:Base or anything like
that. For my company R:base was the BEST Choice.
Why does it seem that there are so many postings about data corruption,
R:Scope, Reload, Pack??
Is this a gerneral problem with database's Orical, Access ext...?
IE Power or network problems.
What other causes are there?
How can they be prevented?
How do other database work with these problems?
Once again!! I am not criticizing R:Base!!! I am only asking because i don't
know
Victor Timmons
Tiz's Door Sales, Inc
425-258-2391
