On Thu, 26 May 2005, Tom Lane wrote:
> Alvaro Herrera <alvherre@surnet.cl> writes:
>> I'm wondering what should happen at prepare time so that "my own cache"
>> is correct.
>
> Good point. As far as the local caches are concerned, we probably have
> to make it look like the transaction rolled back. I think Heikki
> already had code in there to send the right inval messages when the
> prepared transaction ultimately commits ... but we'll have to check that
> that sequence does the right things ...
Looking at the sequence, at least the relcache init file stuff looks if
not broken at least a bit heavy-handed...
BTW: Is there a race condition in the relcache init file invalidation,
even without 2PC?
AtEOXact_Inval does basically this:
1. Unlink init file
2. Send inval messages
3. Unlink the init file again
Now consider this scenario:
backend A: Do updates that cause an init file invalidation
backend A: Commit begins
backend A: unlink init file
backend B starts and recreates init file
backend A: send inval message
backend C starts and reads the now stale init file
The window is admittedly very small, but it just caught my eye. Or am I
missing some lock etc?
- Heikki
