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Thread Backup while live?
Tue, Oct 17 2006 6:29 AMPermanent Link

Am I right in thinking that the backup mechanism will operate happily
while the database is in use by other threads? They'll be reading and
writing, but currently no transactions. Are there any conditions to the
backup?

Also, is it a pure copy of the table, or is it sort of "optimized"? That
is, if I have a load of deleted blobs, do the deleted parts get copied too
so that the database on restore would be exactly as original, or would it
effectively be optimized by having old records deleted.

I ask all this as I'd like a copy of a 24/7 database which has grown to
1.3Gb (blob file) and I want to see what is in it. If I restore and it is
just 0.3Gb, then it wouldn't be the same of course. I guess I could have
my control thread close everything down and then copy the files raw...

/Matthew Jones/
Tue, Oct 17 2006 7:00 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Matthew


I think that backing up will put a lock on the tables so that no inserts/edits can be done.

Roy Lambert
Tue, Oct 17 2006 7:59 AMPermanent Link

Hmm, do they just spin until the backup completes? Or will they fail?
Spinning would be fine.

/Matthew Jones/
Tue, Oct 17 2006 8:14 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Matthew


I thought I'd test my thinking and whilst running a backup from one app I was able to insert and edit data using DBSys.

On that basis over to the guru <vbg>

Roy Lambert
Tue, Oct 17 2006 9:45 AMPermanent Link

"Jose Eduardo Helminsky"
Matthew

I don´t know what kind of data you will backup. But, is is *NOT* a simple
file copy. Remember there are some relationships between files (tables) and
imagine the situation you hold a sum of detail records in the master, you
copy the master and just after the copy finish, other user delete the detail
records. Referencial Integrity will be broken. Unless you use a restricted
transaction locking related tables and copy them to another area then unlock
and do the same for another related tables.

But, even when you are doing a backup, the data can be read with any
problems. They only can´t be changed (add, update or delete).

Eduardo

Tue, Oct 17 2006 9:56 AMPermanent Link

>  running a backup from one app

Oooh - I'd not even thought of doing it from another app. What a good idea
- it could be a support only thing. Hmm. Command line driven even for
remote control and the "screen" user wouldn't even know...

/Matthew Jones/
Tue, Oct 17 2006 4:20 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Matthew,

<< Hmm, do they just spin until the backup completes? Or will they fail?
Spinning would be fine. >>

They spin, but if the backup takes a really long time they will eventually
issue a lock error.  Also, inserts and edits aren't blocked, only Posts or
Deletes, i.e. other clients simply cannot write to the database while it's
being backed up.  They can, however, read from it and lock records.

--
Tim Young
Elevate Software
www.elevatesoft.com

Wed, Oct 18 2006 4:55 AMPermanent Link

Many thanks.

/Matthew Jones/
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