Fix two small bugs in new gistget.c logic.

1. Complain, rather than silently doing nothing, if an "invalid" tuple
is found on a leaf page.  Per off-list discussion with Heikki.

2. Fix oversight in code that removes a GISTSearchItem from the search
queue: we have to reset lastHeap if this was the last heap item in the
parent GISTSearchTreeItem.  Otherwise subsequent additions will do the
wrong thing.  This was probably masked in early testing because in typical
cases the parent item would now be completely empty and would be deleted on
next call.  You'd need a queued non-leaf page at exactly the same distance
as a heap tuple to expose the bug.

diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c
index afff55c78813d6b77f65da61d7ebd2e4463252a4..56921cfee01ab0651d0e7fc616f7605f5b495a51 100644 (file)
--- a/src/backend/access/gist/gistget.c
+++ b/src/backend/access/gist/gistget.c
@@ -70,9 +70,10 @@ gistindex_keytest(IndexScanDesc scan,
        {
                int             i;
 
+               if (GistPageIsLeaf(page))                       /* shouldn't happen */
+                       elog(ERROR, "invalid GIST tuple found on leaf page");
                for (i = 0; i < scan->numberOfOrderBys; i++)
                        so->distances[i] = -get_float8_infinity();
-               *recheck_p = true;              /* probably unnecessary */
                return true;
        }
 
@@ -403,6 +404,8 @@ getNextGISTSearchItem(GISTScanOpaque so)
                {
                        /* Delink item from chain */
                        so->curTreeItem->head = item->next;
+                       if (item == so->curTreeItem->lastHeap)
+                               so->curTreeItem->lastHeap = NULL;
                        /* Return item; caller is responsible to pfree it */
                        return item;
                }