Subject | OAT/OIT/OST questions |
---|---|
Author | Fernando P. Nájera Cano |
Post date | 2015-03-27T12:13:08Z |
Hello,
I have a few questions about the transaction numbers.
The documentation at
http://www.firebirdsql.org/manual/gstat-example-header.html says that
OST is normally the same as OAT.
* When could OST be different to OAT?
* Is it possible to simulate this situation (OST != OAT) by using isql?
If yes, how?
* If OST and OAT are different, which one is higher?
My current understanding is that OIT is always the lowest of the
three, and I think that OAT should be less or equal than OST.
* Is this true, then? OIT <= OAT <= OST
Also, given that OST is the oldest snapshot transaction:
* What happens if there is no current snapshot transaction?
* If the database had never had a snapshot transaction, would this
value be 1 (or 0) while OAT and OIT have moved on?
And one extra question:
* If I'm in the middle of a transaction and the network connection
breaks, what happens to the OAT/OIT/OST - in particular, does any of
them get stuck? If yes, for how long?
Thanks in advance for any help and/or links where I could find
answers.
Best regards,
Fernando Nájera
I have a few questions about the transaction numbers.
The documentation at
http://www.firebirdsql.org/manual/gstat-example-header.html says that
OST is normally the same as OAT.
* When could OST be different to OAT?
* Is it possible to simulate this situation (OST != OAT) by using isql?
If yes, how?
* If OST and OAT are different, which one is higher?
My current understanding is that OIT is always the lowest of the
three, and I think that OAT should be less or equal than OST.
* Is this true, then? OIT <= OAT <= OST
Also, given that OST is the oldest snapshot transaction:
* What happens if there is no current snapshot transaction?
* If the database had never had a snapshot transaction, would this
value be 1 (or 0) while OAT and OIT have moved on?
And one extra question:
* If I'm in the middle of a transaction and the network connection
breaks, what happens to the OAT/OIT/OST - in particular, does any of
them get stuck? If yes, for how long?
Thanks in advance for any help and/or links where I could find
answers.
Best regards,
Fernando Nájera