Detailed report on calculation error in heap_page_prepare_for_xid().

Author: Alexander Korotkov

src/backend/access/heap/heapam.c

@@ -2930,6 +2930,21 @@ heap_page_prepare_for_xid(Relation relation, Buffer buffer,
 			{
 				int64	delta = - (freeDelta + requiredDelta) / 2;
 
+				if (xid < base + delta + FirstNormalTransactionId ||
+					xid > base + delta + MaxShortTransactionId)
+				{
+					elog(FATAL, "Fatal xid base calculation error: "
+						"xid = " XID_FMT ", "
+						"base = " XID_FMT ", "
+						"min = %u, "
+						"max = %u, "
+						"freeDelta = " INT64_FORMAT ", "
+						"requiredDelta = " INT64_FORMAT ", "
+						"delta = " INT64_FORMAT,
+						xid, base, min, max, freeDelta, requiredDelta, delta
+					);
+				}
+
 				Assert(xid >= base + delta + FirstNormalTransactionId);
 				Assert(xid <= base + delta + MaxShortTransactionId);