> 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.
