diff --git a/manifest b/manifest
index 46d27e5e27..04f1f435c4 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Version\s3.25.0
-D 2018-09-15T04:01:47.208
+C Optimization:\swhen\sdoing\san\sUPDATE\son\sa\stable\swith\sindexes\son\san\sexpression,\ndo\snot\supdate\sthe\sexpression\sindexes\sif\sthey\sdo\snot\srefer\sto\sany\sof\sthe\ncolumns\sof\sthe\stable\sbeing\supdated.
+D 2018-09-15T21:38:48.076
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 6b650013511fd9d8b094203ac268af9220d292cc7d4e1bc9fbca15aacd8c7995
@@ -462,7 +462,7 @@ F src/hash.c a12580e143f10301ed5166ea4964ae2853d3905a511d4e0c44497245c7ce1f7a
 F src/hash.h ab34c5c54a9e9de2e790b24349ba5aab3dbb4fd4
 F src/hwtime.h 747c1bbe9df21a92e9c50f3bbec1de841dc5e5da
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
-F src/insert.c c723716f0de7aa0a679300f7d3541c89645f4a9882161cecdb3093fc07f8cc4b
+F src/insert.c 0a214201afec77880a31a59c33d86b473a160fc5cc31981eab2041ae03d8bf2f
 F src/legacy.c 134ab3e3fae00a0f67a5187981d6935b24b337bcf0f4b3e5c9fa5763da95bf4e
 F src/loadext.c 30b140d0e5031924c56f802760506c0a235ced0dff9f3d95119aa86df12856e2
 F src/main.c 1f54ee71990bfbf4cdc2dc79bdc33e7c4f54eef6922447b4c910f9b5885a4478
@@ -506,7 +506,7 @@ F src/shell.c.in 6e0aad854be738a5d0368940459399be211e9ac43aebe92bb9ed46cfe38d0e1
 F src/sqlite.h.in 4b4c2f2daeeed4412ba9d81bc78092c69831fe6eda4f0ae5bf951da51a8dccec
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 305adca1b5da4a33ce2db5bd236935768e951d5651bfe5560ed55cfcdbce6a63
-F src/sqliteInt.h ce34da1aacca2cd4b63803db697f682af95c02d1e1750f240438b0d96a59bdb8
+F src/sqliteInt.h 83ee9b55db521b70294b2858872e69b96d0a4810d8221796def3e99cca5ee663
 F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
 F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -567,7 +567,7 @@ F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
 F src/tokenize.c 9f55961518f77793edd56eee860ecf035d4370ebbb0726ad2f6cada6637fd16b
 F src/treeview.c e7a7f90552bb418533cdd0309b5eb71d4effa50165b880fc8c2001e613577e5f
 F src/trigger.c d3d78568f37fb2e6cdcc2d1e7b60156f15b0b600adec55b83c5d42f6cad250bd
-F src/update.c 345ce35eb1332eb4829857aa8b1f65a614b07dae91d0346c0dc2baacafbcc51b
+F src/update.c deb215e3532be46e1e2b6aa38ed9e3eb96e42ebc4cbe7a498cd365788220a432
 F src/upsert.c 0dd81b40206841814d46942a7337786932475f085716042d0cb2fc7791bf8ca4
 F src/utf.c 810fbfebe12359f10bc2a011520a6e10879ab2a163bcb26c74768eab82ea62a5
 F src/util.c d9eb0a6c4aae1b00a7369eadd7ca0bbe946cb4c953b6751aa20d357c2f482157
@@ -1007,7 +1007,7 @@ F test/index8.test bc2e3db70e8e62459aaa1bd7e4a9b39664f8f9d7
 F test/index9.test 0aa3e509dddf81f93380396e40e9bb386904c1054924ba8fa9bcdfe85a8e7721
 F test/indexedby.test a52c8c6abfae4fbfb51d99440de4ca1840dbacc606b05e29328a2a8ba7cd914e
 F test/indexexpr1.test 635261197bcdc19b9b2c59bbfa7227d525c00e9587faddb2d293c44d287ce60e
-F test/indexexpr2.test 08551aa8956a91582979e17b6d369f321a5cb6ed6d3e952925a3e54e9e7de216
+F test/indexexpr2.test 05f490de32b07bce041947cb63475eb04cbd5af2ea2979ca6b9a694cde176efd
 F test/indexfault.test 31d4ab9a7d2f6e9616933eb079722362a883eb1d
 F test/init.test 15c823093fdabbf7b531fe22cf037134d09587a7
 F test/insert.test 5604b1ff5675cc84c34a5b315792b958f48c32edccc0dafcc81d3b776270b70a
@@ -1765,10 +1765,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 7921dd91a1745aa79ea157b91b22c380e9331800050861ee6ca1f0efa0a97628
-R cd1dec78fa9aef334fc060d76165a055
-T +bgcolor * #d0c0ff
-T +sym-release *
-T +sym-version-3.25.0 *
+P b63af6c3bd33152742648d5d2e8dc5d5fcbcdd27df409272b6aea00a6f761760
+R 3dbbbb152576c732493eb0793eda163f
 U drh
-Z 7af864335c95fcb0688b7f5b8af875de
+Z 14fba317833d2195e2283bec86cb6487
diff --git a/manifest.uuid b/manifest.uuid
index b71e552f9e..dbfdf2d5da 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-b63af6c3bd33152742648d5d2e8dc5d5fcbcdd27df409272b6aea00a6f761760
\ No newline at end of file
+a71b101635ed28a4c99734dabb20bd65ef1018c1d63ac143b7321cdb0fafa5d7
\ No newline at end of file
diff --git a/src/insert.c b/src/insert.c
index 12a6bb805e..d110ab7634 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -1126,14 +1126,15 @@ insert_cleanup:
 #endif
 
 /*
-** Meanings of bits in of pWalker->eCode for checkConstraintUnchanged()
+** Meanings of bits in of pWalker->eCode for 
+** sqlite3ExprReferencesUpdatedColumn()
 */
 #define CKCNSTRNT_COLUMN   0x01    /* CHECK constraint uses a changing column */
 #define CKCNSTRNT_ROWID    0x02    /* CHECK constraint references the ROWID */
 
-/* This is the Walker callback from checkConstraintUnchanged().  Set
-** bit 0x01 of pWalker->eCode if
-** pWalker->eCode to 0 if this expression node references any of the
+/* This is the Walker callback from sqlite3ExprReferencesUpdatedColumn().
+*  Set bit 0x01 of pWalker->eCode if pWalker->eCode to 0 and if this
+** expression node references any of the
 ** columns that are being modifed by an UPDATE statement.
 */
 static int checkConstraintExprNode(Walker *pWalker, Expr *pExpr){
@@ -1155,12 +1156,21 @@ static int checkConstraintExprNode(Walker *pWalker, Expr *pExpr){
 ** only columns that are modified by the UPDATE are those for which
 ** aiChng[i]>=0, and also the ROWID is modified if chngRowid is true.
 **
-** Return true if CHECK constraint pExpr does not use any of the
+** Return true if CHECK constraint pExpr uses any of the
 ** changing columns (or the rowid if it is changing).  In other words,
-** return true if this CHECK constraint can be skipped when validating
+** return true if this CHECK constraint must be validated for
 ** the new row in the UPDATE statement.
+**
+** 2018-09-15: pExpr might also be an expression for an index-on-expressions.
+** The operation of this routine is the same - return true if an only if
+** the expression uses one or more of columns identified by the second and
+** third arguments.
 */
-static int checkConstraintUnchanged(Expr *pExpr, int *aiChng, int chngRowid){
+int sqlite3ExprReferencesUpdatedColumn(
+  Expr *pExpr,    /* The expression to be checked */
+  int *aiChng,    /* aiChng[x]>=0 if column x changed by the UPDATE */
+  int chngRowid   /* True if UPDATE changes the rowid */
+){
   Walker w;
   memset(&w, 0, sizeof(w));
   w.eCode = 0;
@@ -1175,7 +1185,7 @@ static int checkConstraintUnchanged(Expr *pExpr, int *aiChng, int chngRowid){
   testcase( w.eCode==CKCNSTRNT_COLUMN );
   testcase( w.eCode==CKCNSTRNT_ROWID );
   testcase( w.eCode==(CKCNSTRNT_ROWID|CKCNSTRNT_COLUMN) );
-  return !w.eCode;
+  return w.eCode!=0;
 }
 
 /*
@@ -1381,7 +1391,13 @@ void sqlite3GenerateConstraintChecks(
     for(i=0; i<pCheck->nExpr; i++){
       int allOk;
       Expr *pExpr = pCheck->a[i].pExpr;
-      if( aiChng && checkConstraintUnchanged(pExpr, aiChng, pkChng) ) continue;
+      if( aiChng
+       && !sqlite3ExprReferencesUpdatedColumn(pExpr, aiChng, pkChng)
+      ){
+        /* The check constraints do not reference any of the columns being
+        ** updated so there is no point it verifying the check constraint */
+        continue;
+      }
       allOk = sqlite3VdbeMakeLabel(v);
       sqlite3VdbeVerifyAbortable(v, onError);
       sqlite3ExprIfTrue(pParse, pExpr, allOk, SQLITE_JUMPIFNULL);
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 79d41e8a03..74438b5abc 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -4002,6 +4002,7 @@ void sqlite3GenerateRowDelete(
 void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*, int);
 int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int, int*,Index*,int);
 void sqlite3ResolvePartIdxLabel(Parse*,int);
+int sqlite3ExprReferencesUpdatedColumn(Expr*,int*,int);
 void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,
                                      u8,u8,int,int*,int*,Upsert*);
 #ifdef SQLITE_ENABLE_NULL_TRIM
diff --git a/src/update.c b/src/update.c
index 94e169fd01..c9ec95bb65 100644
--- a/src/update.c
+++ b/src/update.c
@@ -79,6 +79,29 @@ void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i, int iReg){
 #endif
 }
 
+/*
+** Check to see if column iCol of index pIdx references any of the
+** columns defined by aXRef and chngRowid.  Return true if it does
+** and false if not.
+**
+** The iCol-th column of pIdx will be an expression.
+**
+** aXRef[j] will be non-negative if column j of the original table is
+** being updated.  chngRowid will be true if the rowid of the table is
+** being updated.
+*/
+static int indexExprRefsUpdatedColumn(
+  Index *pIdx,      /* The index containing the expression to analyze */
+  int iCol,         /* Which column of the index is the expression */
+  int *aXRef,       /* aXRef[j]>=0 if column j is being updated */
+  int chngRowid     /* true if the rowid is being updated */
+){
+  assert( pIdx->aColExpr!=0 );
+  assert( pIdx->aColExpr->a[iCol].pExpr!=0 );
+  return sqlite3ExprReferencesUpdatedColumn(pIdx->aColExpr->a[iCol].pExpr,
+                                            aXRef,chngRowid);
+}
+
 /*
 ** Process an UPDATE statement.
 **
@@ -302,8 +325,6 @@ void sqlite3Update(
   /* There is one entry in the aRegIdx[] array for each index on the table
   ** being updated.  Fill in aRegIdx[] with a register number that will hold
   ** the key for accessing each index.
-  **
-  ** FIXME:  Be smarter about omitting indexes that use expressions.
   */
   for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
     int reg;
@@ -314,7 +335,11 @@ void sqlite3Update(
       reg = 0;
       for(i=0; i<pIdx->nKeyCol; i++){
         i16 iIdxCol = pIdx->aiColumn[i];
-        if( iIdxCol<0 || aXRef[iIdxCol]>=0 ){
+        if( (iIdxCol>=0 && aXRef[iIdxCol]>=0)
+         || iIdxCol==XN_ROWID
+         || (iIdxCol==XN_EXPR
+             && indexExprRefsUpdatedColumn(pIdx,i,aXRef,chngRowid))
+        ){
           reg = ++pParse->nMem;
           pParse->nMem += pIdx->nColumn;
           if( (onError==OE_Replace)
diff --git a/test/indexexpr2.test b/test/indexexpr2.test
index aed887a848..856992201e 100644
--- a/test/indexexpr2.test
+++ b/test/indexexpr2.test
@@ -159,5 +159,43 @@ do_execsql_test 3.4.6 {
   SELECT * FROM t4 ORDER BY Substr(a,-2) COLLATE binary;
 } {.ABC1 1 .ABC3 3 .abc2 2 .abc4 4}
 
+# 2014-09-15:  Verify that UPDATEs of columns not referenced by a
+# index on expression do not modify the index.
+#
+unset -nocomplain cnt
+set cnt 0
+proc refcnt {x} {
+  global cnt
+  incr cnt
+  return $x
+}
+db close
+sqlite3 db :memory:
+db function refcnt -deterministic refcnt
+do_test 4.100 {
+  db eval {
+    CREATE TABLE t1(a,b,c,d,e,f);
+    CREATE INDEX t1abc ON t1(refcnt(a+b+c));
+  }
+  set ::cnt
+} {0}
+do_test 4.110 {
+  db eval {INSERT INTO t1 VALUES(1,2,3,4,5,6);}
+  set ::cnt
+  # The refcnt() function is invoked once to compute the index value 
+} {1}
+do_test 4.120 {
+  set ::cnt 0
+  db eval {UPDATE t1 SET b=b+1;}
+  set ::cnt
+  # The refcnt() function is invoked twice, once to remove the old index
+  # entry and a second time to insert the new one.
+} {2}
+do_test 4.130 {
+  set ::cnt 0
+  db eval {UPDATE t1 SET d=d+1;}
+  set ::cnt
+  # Refcnt() should not be invoked because that index does not change.
+} {0}
 
 finish_test