"Florian G. Pflug" <[EMAIL PROTECTED]> writes: > Currently, we do not assume that either the childXids array, nor > the xid cache in the proc array are sorted by ascending xid order. > I believe that we could simplify the code, further reduce the locking > requirements, and enabled a transaction to de-overflow it's xid cache > if we assume that those arrays are in ascending xid order.
"de-overflowing" the cache sounds completely unsafe, as other backends need that state to determine whether they need to look into pg_subtrans. I still don't believe you can avoid taking exclusive lock, either; your argument here did not address latestCompletedXid. But the main point remains this: there is no evidence whatsoever that these code paths are sufficiently performance-critical to be worth speeding up by making the code more fragile. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate