Subject Re: [firebird-support] Two transactions can have the same TID?
Author W O
Post date 2013-09-09T01:43:09Z
Thank you very much for answering me, Helen

Well, I had not expressed well. My program does a full backup with GBAK every day, another full backup with NBACKUP and several incremental backups, all automatically. It does restore (when needed), send the backups to a web site, receive the backups from that web site (when the user wants), validation, recalculation of statistics, recreation of indices, assign roles and privilegies and several another jobs, too. Is very useful for me and my clients because with just a program we can do all the admin jobs.

So, going back to the theme, if I am understanding you correctly:

1. The database has 2.000.000.000 of commited transactions

2. I do a cycle backup/restore

3. The restored database can have another 2.000.000.000 of commited transactions, doing a total of 4.000.000.000 of commited transactions. Is that right?

Greetings.

Walter.







On Sun, Sep 8, 2013 at 8:53 PM, Helen Borrie <helebor@...> wrote:
 

At 11:53 a.m. 9/09/2013, W O wrote:

>Thank you very much for your answer Helen.
>
>I do backups every day, one full and several incrementals. Well, rather it is done automatically by my program.

That sounds like nBackup. Restoring from nBackups does NOT reset the transaction counter. You need to do a gbak backup and RESTORE that backup to start a fresh counter cycle. How often depends on how fast you are eating TIDs. Use gstat to monitor that.


>I understand that each commited (and not commited, of course) row keeps the number of its TID, so that number is always present in the row. When after a cycle backup/restore the Next Transaction is 1 because all the integer numbers were used, what happens? that database cannot be used anymore for inserts, updates and deletes?

A database restored from a gbak backup has no transaction artifacts left from the old database. If you let the TID counter go right up to the wire with active users then be prepared for corruption in some shape or form.


Helen Borrie, Support Consultant, IBPhoenix (Pacific)
Author of "The Firebird Book" and "The Firebird Book Second Edition"
http://www.firebird-books.net
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