Re: BUG #16134: Assertion fails on CREATE gist INDEX over intarray

PG Bug reporting form <noreply@postgresql.org> writes:
> When running the following script (repeated to improve reproducing):
> ...
> Server (compiled with cassert) crashes:

Yup, reproduced here.  What I see is that gistnospace is being told
to account for a "to-be-deleted" tuple that is off the end of the
page's line pointer array.  Tracing back to see where that tuple
number is coming from, it seems to originate in gistfinishsplit:

    gistinserttuples(state, stack->parent, giststate,
                     tuples, 2,
                     stack->downlinkoffnum,
                     left->buf, right->buf,
                     true,        /* Unlock parent */
                     unlockbuf    /* Unlock stack->buffer if caller wants that */
);

That is, the stack->downlinkoffnum tuple index doesn't jibe with the
actual state of the stack->parent page.

What I suspect has happened is that the stack->parent page itself
got split during some recursive split, and the stacked info wasn't
updated.  I don't know this code well enough to be sure though,
and I definitely don't wish to be the one to fix it.

            regards, tom lane