Re: how to copy live paradox tables
- From: "Robert Molyneux" <ibisnest_removeantispam_@xxxxxxxxxxxx>
- Date: Fri, 1 Sep 2006 10:27:52 +1000
John,
Provided no one is using the Paradox database, you can safely make a copy of
the entire directory using the OS tools.
You can find out if anyone is using a copy by searching for files like
*.lck.
If there are none, you know no-one is using the database using the Borland
Database Engine.
If there are any *.lck files, and you can delete them, they have been left
over through the BDE being abended.
Provided that none of the tables use lookups outside the tables' directory,
you can be confident that the copied database has RI and other checks in
place.
There is a design fault in Paradox that allows for lookups to be set for a
table in Directory A to tables in Directory B, but the path for Directory B
is hard-coded into the table meta-data, so a copy in another volume would
lose track of the lookups. RI can only be between tables in the same
directory.
You can easily check for this by moving the database copy to another volume
and trying to open all tables. Provided you have enough memory, you can open
all tables in a directory at once.
You can easily effectively lock an entire database simply by renaming its
directory for the duration of a copy:
1. Check for *.lck files. Handle any occurences.
2. Rename the database directory
3. Copy it.
4. Rename back to original.
BUT:
You have not said what you are trying to achieve by this.
Why make copies of the database? Can't you use the production version?
If all you want is a few tables, you might be able to snapshot them safely
during operation.
One of the joys of Paradox is that you can safely work on individual tables.
So for example, if the production database contains hundreds of tables, but
you only need one or two, you can copy them either with Paradox or the OS,
work on them, and put them back, without requiring the production database
to be shut down.
You can use the date and time stamp on the table component files to see
whether it is in use or not, or has been changed since the last copy.
"john ligda" <jligda@xxxxxxxxxxxxx> wrote in message
news:44f62acf$1@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Hello, I am very new to paradox databases but have some familiarity with
Oracle and MS SQL rdbms concepts. I would like to learn how to safely
copy
paradox data files while the database is operatonal. Is this possible?
Im used to some sort of admin tool which hides the complexity involved in
preserving a valid database state. I have no idea if such a tool exists
for paradox databases. To add to the confusion, I will not be allowed to
touch the production tables myself. I will instead, be prviding a safe
solution
to the administrator so that he can provide me with consistant refreshes
of the production tables. We want to do this nightly.
Our first attempt was to simply copy the data directory with Windows OS
commands.
He delivered a directory of .DB, .TV, .PX files. I was able to extract
data from the .DB tables but have no idea if the data transaction
integrity
is preserved. In fact, on one table there is a violation of the primary
key on the very last record. I suspect the copy is corrupt because of the
way it was copied. But honestly i have no idea. Can anyone direct me to
a resource where I can read about basic administration for paradox
databases?
Specifically how to safely copy/mirror/replicate source systems without
affecting daily operations of end users.
.
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