Subject RE: [firebird-support] Transaction ID overflow
Author Brian Dunstan

Thanks Mark.


From: <>
Sent: Tuesday, 1 May 2018 5:34 PM
Subject: Re: [firebird-support] Transaction ID overflow



On 1-5-2018 09:19, Brian Dunstan brian.dunstan@...
[firebird-support] wrote:

> Hi,
> We have a big customer here who processes large numbers of transactions into a large database and plans to not backup and restore.

They should plan for backups and tests restores. But if you reach the
transaction limit, then there is really no choice but to backup and restore.

> We are using Dialect 3. I think that means that the TID is 32 bits. I think that means they get 4,294,967,296 transactions before overflow - I'm assuming the TID is an unsigned integer. Is that correct?

In Firebird 2.5 and earlier the transaction id is 32 bit. If I'm not
mistaken, it is signed (so effectively 31 bits) with a maximum
transaction id of 2^31 - 1.

> If we move to dialect 3, does the TID become 64 bits?

I assume you mean Firebird 3. In Firebird 3 the transaction id is 48
bits (unsiged), the maximum transaction id is 2^48.

Mark Rotteveel