Re: Deadlock possibility in _bt_check_unique?

> No, you don't understand how it works. All would-be inserters will hit
> the same target page to begin with, ie, the first one that the new key
> could legally be inserted on. The lock that protects against this
> problem is the lock on that page, regardless of which page the key
> actually ends up on.
>
>
Consider Time instances T1, T2, T3, T4

T1 : session 1 holds the write lock on page p1 and completes the unique
check on p1, p2 and p3.

T2 : session 1 releases the lock on p1 (its waiting to acquire a ex lock on
p2)

T3 : session 2 acquires write lock on p1 and completes the unique check on
p1, p2 and p3. Here, i believe the Session 2
has a chance of getting the read lock before session 1 gets the write lock.
Is it not possible?

T4 : session 1 gets the write lock on p2 and inserts and session 2 gets the
write lock on p1 and inserts.

OK. I have stated my assumptions. Is my assumption at time instant T3 wrong/
never happen?

Thanks,
Gokul.