2011/3/30 Robert Haas <robertmh...@gmail.com> > Maybe we could check PD_ALL_VISIBLE before > taking the buffer lock - if it appears to be set, then we pin the > visibility map page before taking the buffer lock. Otherwise, we take > the buffer lock at once. Either way, once we have the lock, we > recheck the bit. Only if it's set and we haven't got a pin do we need > to do the drop-lock-pin-reacquire-lock dance. Is that at all > sensible? >
But only lock can make sure the page has enough free space. If we try the drop-lock-...-lock dance, we may fall into a dead loop. -- GaoZengqi pgf...@gmail.com zengqi...@gmail.com
