Index: ext/session/session2.test
==================================================================
--- ext/session/session2.test
+++ ext/session/session2.test
@@ -112,25 +112,46 @@
   CREATE TABLE t3(a, b, c, PRIMARY KEY(a, b));
 }
 
 foreach {tn sql} {
   1 { INSERT INTO t1 VALUES(1, 2) } 
+
   2 {
     INSERT INTO t2 VALUES(1, NULL);
     INSERT INTO t2 VALUES(2, NULL);
     INSERT INTO t2 VALUES(3, NULL);
     DELETE FROM t2 WHERE a = 2;
     INSERT INTO t2 VALUES(4, NULL);
     UPDATE t2 SET b=0 WHERE b=1;
   } 
+
   3 { INSERT INTO t3 SELECT *, NULL FROM t2 }
+
   4 {
     INSERT INTO t3 SELECT a||a, b||b, NULL FROM t3;
     DELETE FROM t3 WHERE rowid%2;
   }
+
   5 { UPDATE t3 SET c = a||b }
+
   6 { UPDATE t1 SET a = 32 }
+
+  7 { 
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --    2
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --    4
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --    8
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --   16
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --   32
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --   64
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --  128
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --  256
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; --  512
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; -- 1024
+    INSERT INTO t1 SELECT randomblob(32), randomblob(32) FROM t1; -- 2048
+    DELETE FROM t1 WHERE (rowid%3)==0;
+  }
+
 } {
   do_then_apply_sql $sql
   do_test $tn { compare_db db db2 } {}
 }
 

Index: ext/session/sqlite3session.c
==================================================================
--- ext/session/sqlite3session.c
+++ ext/session/sqlite3session.c
@@ -263,33 +263,35 @@
 
   *pnWrite += nByte;
   return SQLITE_OK;
 }
 
-#define HASH_APPEND(hash, add) ((hash) << 3) ^ (hash) ^ (int)(add)
-static int sessionHashAppendI64(int h, i64 i){
+#define HASH_APPEND(hash, add) ((hash) << 3) ^ (hash) ^ (unsigned int)(add)
+static unsigned int sessionHashAppendI64(unsigned int h, i64 i){
   h = HASH_APPEND(h, i & 0xFFFFFFFF);
   return HASH_APPEND(h, (i>>32)&0xFFFFFFFF);
 }
-static int sessionHashAppendBlob(int h, int n, const u8 *z){
+static unsigned int sessionHashAppendBlob(unsigned int h, int n, const u8 *z){
   int i;
   for(i=0; i<n; i++) h = HASH_APPEND(h, z[i]);
   return h;
 }
 
 /*
-** This function calculates a hash based on the primary key values of
-** the old.* or new.* row currently available.
+** This function may only be called from within a pre-update callback.
+** It calculates a hash based on the primary key values of the old.* or 
+** new.* row currently available. The value returned is guaranteed to
+** be less than pTab->nBucket.
 */
-static int sessionPreupdateHash(
+static unsigned int sessionPreupdateHash(
   sqlite3 *db,                    /* Database handle */
   SessionTable *pTab,             /* Session table handle */
   int bNew,                       /* True to hash the new.* PK */
   int *piHash                     /* OUT: Hash value */
 ){
-  int h = 0;
-  int i;
+  unsigned int h = 0;             /* Hash value to return */
+  int i;                          /* Used to iterate through columns */
 
   assert( pTab->nCol==sqlite3_preupdate_count(db) );
   for(i=0; i<pTab->nCol; i++){
     if( pTab->abPK[i] ){
       int rc;
@@ -333,19 +335,25 @@
 
   *piHash = (h % pTab->nChange);
   return SQLITE_OK;
 }
 
-static int sessionChangeHash(
-  sqlite3 *db,
-  SessionTable *pTab,
-  SessionChange *pChange,
-  int nBucket
+/*
+** Based on the primary key values stored in change pChange, calculate a
+** hash key, assuming the has table has nBucket buckets. The hash keys
+** calculated by this function are compatible with those calculated by
+** sessionPreupdateHash().
+*/
+static unsigned int sessionChangeHash(
+  sqlite3 *db,                    /* Database handle */
+  SessionTable *pTab,             /* Table handle */
+  SessionChange *pChange,         /* Change handle */
+  int nBucket                     /* Assume this many buckets in hash table */
 ){
-  int h = 0;
-  int i;
-  u8 *a = pChange->aRecord;
+  unsigned int h = 0;             /* Value to return */
+  int i;                          /* Used to iterate through columns */
+  u8 *a = pChange->aRecord;       /* Used to iterate through change record */
 
   for(i=0; i<pTab->nCol; i++){
     int eType = *a++;
     int isPK = pTab->abPK[i];