Re: Possible duplicate release of buffer lock.

Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> writes:
> My point here is that if concurrent deletion can't be perfomed by
> the current implement, this while loop could be removed and
> immediately error out or log a message,

>> if (P_ISDELETED(opaque) || opaque->btpo_next != target)
>> {
>> elog(ERROR, "no left sibling of page %d (concurrent deletion?) in \"%s\"",..

That would certainly break things: there are valid cases for the
loop to need to iterate, specifically where the left sibling got
split before we could acquire lock on it.

> or, the while loop at least should stop before overshooting the
> target.

>> while (P_ISDELETED(opaque) || opaque->btpo_next != target)
>> {
>> /* step right one page */
>> leftsib = opaque->btpo_next;
>> _bt_relbuf(rel, lbuf);
>> if (leftsib == target || leftsib == P_NONE)
>> {
>> elog(ERROR, "no left sibling of page %d (concurrent deletion?) in \"%s\"",..

Huh? Surely that added test condition could never be true because
of the second part of the while() test.

regards, tom lane