[rucksack-devel] Transactions: abort early?

[Nikodemus Siivola]

"Arthur Lemmens" <alemmens at xs4all.nl> writes:

> This may sound strange coming from me, but for prevalent objects I'd
> seriously consider using two-phase locking (acquire a lock for each object
> when you access it and release all locks at the end of the transaction).

>>  Transaction T1 starts.
>>  T1 does stuff, but doesn't read or write object O.
>>  Transaction T2 starts.
>>  T2 touches O.
>>  T2 commits.
>>  T1 reads 0.

>> Option 1b:
>>
>>  * We no longer have access to O that matches the rest of the T1.
>>    Abort T1 immediately.

If I understand correctly two-phase locking comes down to this,
actually. At the time when T1 reads O it has been changed by a younger
transaction, and no longer matches the rest of T1.

(Assuming serializable transactions are the goal.)

Cheers,

  -- Nikodemus              Schemer: "Buddha is small, clean, and serious."
                   Lispnik: "Buddha is big, has hairy armpits, and laughs."