Griggs, Donald
<[EMAIL PROTECTED]>
wrote:
Regarding: "...As Igor pointed out this does not resemble a full
implementation of transactions, as nested transactions can be
committed
and rolled back independently of the outer parent transaction."
Nonetheless, it would seem, just from the couple of pages below, that
some DB vendors find the less-than-full implementation of nested
transactions to be useful for at least some purposes.
(I.e., an implementation in which inner transactions do little more
than
adjust counters. If anything is rolled back, then entire outer
transaction is rolled back.)
I make no claim to being an expert here -- I'm just a googler. ;-)
[quotes from documentation that only deal with COMMIT snipped]
The interesting question is not what happens on commit of a nested
transaction (the answer is "nothing much" for all reasonable DBMS), but
what happens on _rollback_. A full implementation would roll back to the
state at which nested transaction originated, and keep the enclosing
transaction(s) open. A simple implementation would roll back all
outstanding transactions and discard all changes.
Igor Tandetnik
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