However, page might be exclusively locked before. And in this case CheckForSerializableConflictIn() would be skipped. That happens very rarely (someone fixes incomplete split before we did), but nevertheless.
if xlocked = true, page was already checked for conflict after setting exclusive lock on it's buffer. I still do not see any problem here...
What happen if exactly this "continue" fires?
if (GistFollowRight(stack->page)) { if (!xlocked) { LockBuffer(stack->buffer, GIST_UNLOCK); LockBuffer(stack->buffer, GIST_EXCLUSIVE); xlocked = true; /* someone might've completed the split when we unlocked */ if (!GistFollowRight(stack->page)) continue;
In this case we might get xlocked == true without calling CheckForSerializableConflictIn(). This is very rare codepath, but still...
I think it would be rather safe and easy for understanding to more CheckForSerializableConflictIn() directly before gistinserttuple().
------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
