Fix ancient docs/comments thinko: XID comparison is mod 2^32, not 2^31.

Pointed out by Gianni Ciolli.

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 616e41d52d2986cb2ab1699d2acb76bc5e40d9ef..ca1e82018f9a1e935ebf4e05bf799a909c9de8e1 100644 (file)
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -401,7 +401,7 @@
     as <literal>FrozenXID</>.  This XID does not follow the normal XID
     comparison rules and is always considered older
     than every normal XID. Normal XIDs are
-    compared using modulo-2<superscript>31</> arithmetic. This means
+    compared using modulo-2<superscript>32</> arithmetic. This means
     that for every normal XID, there are two billion XIDs that are
     <quote>older</> and two billion that are <quote>newer</>; another
     way to say it is that the normal XID space is circular with no

diff --git a/src/backend/access/transam/transam.c b/src/backend/access/transam/transam.c
index 3cc0096d92ab016e94165d5a2e12fd8e9ebabdc1..b92a27bff36177c8c4529a56e4ae0246f5c46928 100644 (file)
--- a/src/backend/access/transam/transam.c
+++ b/src/backend/access/transam/transam.c
@@ -301,7 +301,7 @@ TransactionIdPrecedes(TransactionId id1, TransactionId id2)
 {
        /*
         * If either ID is a permanent XID then we can just do unsigned
-        * comparison.  If both are normal, do a modulo-2^31 comparison.
+        * comparison.  If both are normal, do a modulo-2^32 comparison.
         */
        int32           diff;