Fix bug in freespace calculation in heap_multi_insert().

If the amount of freespace on page was less than the amount reserved by
fillfactor, the calculation would underflow.

This fixes bug #6643 reported by Tomonari Katsumata.

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 7e4c8f52ab2a503cae4b0fd15d6be1fa0adb4bd5..0d6fe3f0acd38a87af759bd3d5196da504202486 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2159,7 +2159,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
        {
            HeapTuple   heaptup = heaptuples[ndone + nthispage];
 
-           if (PageGetHeapFreeSpace(page) - saveFreeSpace < MAXALIGN(heaptup->t_len))
+           if (PageGetHeapFreeSpace(page) < MAXALIGN(heaptup->t_len) + saveFreeSpace)
                break;
 
            RelationPutHeapTuple(relation, buffer, heaptup);