Added code to INSERT, DELETE and UPDATE virtual tables. The new code is

mostly untested. (CVS 3248)

FossilOrigin-Name: 32c97b884b104d120db3c0a87f5eab28f36851f8

11 files changed, 177 insertions, 62 deletions

diff --git a/manifest b/manifest
index ad0c30492..aa8f70ac6 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Better\sdocumentation\son\sthe\slimits\sof\suser-defined\sfunctions.\s\sAnd\sa\nmarginally\sbetter\serror\smessage\swhen\sthose\slimits\sare\sexceeded.\nTicket\s#1847.\s(CVS\s3247)
-D 2006-06-14T15:35:37
+C Added\scode\sto\sINSERT,\sDELETE\sand\sUPDATE\svirtual\stables.\s\sThe\snew\scode\sis\nmostly\suntested.\s(CVS\s3248)
+D 2006-06-14T19:00:21
 F Makefile.in 200f6dc376ecfd9b01e5359c4e0c10c02f649b34
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -36,17 +36,17 @@ F src/attach.c 27a31d3b89d7ebb5b358847607b1ec795384123c
 F src/auth.c 9ae84d2d94eb96195e04515715e08e85963e96c2
 F src/btree.c ed343b3dbcbc7da9ac481ef2b98c4239fe6d9629
 F src/btree.h 40055cfc09defd1146bc5b922399c035f969e56d
-F src/build.c 133a046cef19c8bc80dafb38bb82229caefd6fff
+F src/build.c 076619b2a5cbdbdabf5201fc45dda488d7f3cbe6
 F src/callback.c fd9bb39f7ff6b52bad8365617abc61c720640429
 F src/complete.c 7d1a44be8f37de125fcafd3d3a018690b3799675
 F src/date.c cd2bd5d1ebc6fa12d6312f69789ae5b0a2766f2e
-F src/delete.c f9a8c7837adb4bb4810a698a041a88d5ec7bfa9a
+F src/delete.c d529fe3e20d87af628c0078fc33a3e717bb511cf
 F src/experimental.c 1b2d1a6cd62ecc39610e97670332ca073c50792b
-F src/expr.c 8c873e05436ca8ee0ac4c7825d35ff898abb9c89
+F src/expr.c 78b521337d628b1fd9d87b12dbbe771247aab585
 F src/func.c 01e559893b5e43bea85135ad3e481d86c447942a
 F src/hash.c 449f3d6620193aa557f5d86cbc5cc6b87702b185
 F src/hash.h 1b3f7e2609141fd571f62199fc38687d262e9564
-F src/insert.c 2c3eeb4bcde13c1006824ef14953c2fdad31cf36
+F src/insert.c bda00a0e4be8bf4e591186e710075662781293d0
 F src/legacy.c fa15d505dd4e45044177ee4d1c6aeaf8c836d390
 F src/loadext.c d8c7bd14e6ebc4e9f1ff269475bf63e131919449
 F src/main.c 4e48472d06ac3fc0250023e2eb406fc7d8d0a27c
@@ -74,7 +74,7 @@ F src/server.c 087b92a39d883e3fa113cae259d64e4c7438bc96
 F src/shell.c ad73192b30a338a58fe81183d4a5d5a1d4e51d36
 F src/sqlite.h.in b1ecebd3154cf49ba189193f7bdc10a78a9394a2
 F src/sqlite3ext.h 127bd394c8eea481f2ac9b754bf399dbfc818b75
-F src/sqliteInt.h e8710fd5c10c03ca4a2fb49802b8aae6689f27a0
+F src/sqliteInt.h 5a806625f0e9400419d60f74dccef44569dd7871
 F src/table.c f64ec4fbfe333f8df925bc6ba494f55e05b0e75e
 F src/tclsqlite.c 4ad22f354b6e4e137889000e9f585a0590ca39c5
 F src/test1.c 40f20775903bc76d3be3e7c026dddcbc221c1cb0
@@ -91,12 +91,12 @@ F src/test_md5.c 6c42bc0a3c0b54be34623ff77a0eec32b2fa96e3
 F src/test_server.c a6460daed0b92ecbc2531b6dc73717470e7a648c
 F src/test_tclvar.c d434037c1730cfffbf007ac82f1c405d7155a92a
 F src/tokenize.c 6ebcafa6622839968dda4418a7b6945f277a128f
-F src/trigger.c 48bbb94c11954c8e132efcc04478efe8304c4196
-F src/update.c 0186f09414a6578156d40666becc964f85c2a616
+F src/trigger.c 0fc40125820409a6274834a6e04ad804d96e2793
+F src/update.c 5e638a61102776c0f0333994e18361b40598b44f
 F src/utf.c ab81ac59084ff1c07d421eb1a0a84ec809603b44
 F src/util.c ca6ee72772c0f5dc04d2e0ab1973fd3b6a9bf79d
 F src/vacuum.c 5b37d0f436f8e1ffacd17934e44720b38d2247f9
-F src/vdbe.c 337ef4045ade927fa77192d0d040001b2386fba3
+F src/vdbe.c 64427e4b088ee26e9a8710724ef0a8ab5b9fd1e6
 F src/vdbe.h 258b5d1c0aaa72192f09ff0568ce42b383f156fa
 F src/vdbeInt.h 6ccb7eaae76ebd761470f6a035501ff33aa92c20
 F src/vdbeapi.c 6af0e7160af260052a7a4500464221a03dada75f
@@ -104,7 +104,7 @@ F src/vdbeaux.c de49c1943146ad97538bc2bb0bce7f2c5e5db4f2
 F src/vdbefifo.c 9efb94c8c3f4c979ebd0028219483f88e57584f5
 F src/vdbemem.c 5f0afe3b92bb2c037f8d5d697f7c151fa50783a3
 F src/vtab.c 507cbb4e2101900339ce88e57144cc01dafa374e
-F src/where.c 299c385e32a7b98d42864c7c83cdc6a778fae562
+F src/where.c 393022cb4ac77d1f00d9c27540ce13ca5486c5b0
 F tclinstaller.tcl 046e3624671962dc50f0481d7c25b38ef803eb42
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/all.test 5df90d015ca63fcef2a4b62c24f7316b66c4bfd4
@@ -366,7 +366,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P 676de55b28f0b22cf78f5e71f4a960f3d76c2d72
-R a8a1cc8c95b40bc320a675a33fc7e864
+P 0d369ff071d296501cc33d4622144b22946ac555
+R 0b4c2c0c45eeadd2de545aaca4dfef08
 U drh
-Z a5cbc134908c784d2a3323e83c952926
+Z 2664815c8d0942e02de99ff6b38443c3
diff --git a/manifest.uuid b/manifest.uuid
index c5f3627f5..3975ebc30 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-0d369ff071d296501cc33d4622144b22946ac555
\ No newline at end of file
+32c97b884b104d120db3c0a87f5eab28f36851f8
\ No newline at end of file
diff --git a/src/build.c b/src/build.c
index 535ccca8d..cd6f290c4 100644
--- a/src/build.c
+++ b/src/build.c
@@ -22,7 +22,7 @@
 **     COMMIT
 **     ROLLBACK
 **
-** $Id: build.c,v 1.399 2006/06/12 16:01:22 danielk1977 Exp $
+** $Id: build.c,v 1.400 2006/06/14 19:00:21 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -1655,7 +1655,7 @@ int sqlite3ViewGetColumnNames(Parse *pParse, Table *pTable){
   if( sqlite3VtabCallConnect(pParse, pTable) ){
     return SQLITE_ERROR;
   }
-  if( pTable->isVirtual ) return 0;
+  if( IsVirtual(pTable) ) return 0;
 #endif
 
 #ifndef SQLITE_OMIT_VIEW
@@ -1981,11 +1981,9 @@ void sqlite3DropTable(Parse *pParse, SrcList *pName, int isView, int noErr){
     /* Remove the table entry from SQLite's internal schema and modify
     ** the schema cookie.
     */
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-    if( pTab->isVirtual ){
+    if( IsVirtual(pTab) ){
       sqlite3VdbeOp3(v, OP_VDestroy, iDb, 0, pTab->zName, 0);
     }
-#endif
     sqlite3VdbeOp3(v, OP_DropTable, iDb, 0, pTab->zName, 0);
     sqlite3ChangeCookie(db, v, iDb);
   }
diff --git a/src/delete.c b/src/delete.c
index e16597d8a..37b8577d8 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** in order to generate code for DELETE FROM statements.
 **
-** $Id: delete.c,v 1.123 2006/06/11 23:41:55 drh Exp $
+** $Id: delete.c,v 1.124 2006/06/14 19:00:21 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -42,8 +42,12 @@ Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
 ** writable return 0;
 */
 int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
-  if( pTab->readOnly && (pParse->db->flags & SQLITE_WriteSchema)==0
-        && pParse->nested==0 ){
+  if( (pTab->readOnly && (pParse->db->flags & SQLITE_WriteSchema)==0
+        && pParse->nested==0) 
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+      || (pTab->pModule && pTab->pModule->xUpdate==0)
+#endif
+  ){
     sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
     return 1;
   }
@@ -66,7 +70,9 @@ void sqlite3OpenTable(
   Table *pTab,    /* The table to be opened */
   int opcode      /* OP_OpenRead or OP_OpenWrite */
 ){
-  Vdbe *v = sqlite3GetVdbe(p);
+  Vdbe *v;
+  if( IsVirtual(pTab) ) return;
+  v = sqlite3GetVdbe(p);
   assert( opcode==OP_OpenWrite || opcode==OP_OpenRead );
   sqlite3TableLock(p, iDb, pTab->tnum, (opcode==OP_OpenWrite), pTab->zName);
   sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
@@ -205,7 +211,7 @@ void sqlite3DeleteFrom(
   ** It is easier just to erase the whole table.  Note, however, that
   ** this means that the row change count will be incorrect.
   */
-  if( pWhere==0 && !triggers_exist ){
+  if( pWhere==0 && !triggers_exist && !IsVirtual(pTab) ){
     if( db->flags & SQLITE_CountRows ){
       /* If counting rows deleted, just count the total number of
       ** entries in the table. */
@@ -243,7 +249,7 @@ void sqlite3DeleteFrom(
 
     /* Remember the rowid of every item to be deleted.
     */
-    sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
+    sqlite3VdbeAddOp(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur, 0);
     sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);
     if( db->flags & SQLITE_CountRows ){
       sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
@@ -304,7 +310,14 @@ void sqlite3DeleteFrom(
       }
 
       /* Delete the row */
-      sqlite3GenerateRowDelete(db, v, pTab, iCur, pParse->nested==0);
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+      if( IsVirtual(pTab) ){
+        sqlite3VdbeOp3(v, OP_VUpdate, 0, 1, (const char*)pTab->pVtab, P3_VTAB);
+      }else
+#endif
+      {
+        sqlite3GenerateRowDelete(db, v, pTab, iCur, pParse->nested==0);
+      }
     }
 
     /* If there are row triggers, close all cursors then invoke
@@ -327,7 +340,7 @@ void sqlite3DeleteFrom(
     sqlite3VdbeResolveLabel(v, end);
 
     /* Close the cursors after the loop if there are no row triggers */
-    if( !triggers_exist ){
+    if( !triggers_exist && !IsVirtual(pTab) ){
       for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
         sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
       }
diff --git a/src/expr.c b/src/expr.c
index d9f24c37b..43e1c715e 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -12,7 +12,7 @@
 ** This file contains routines used for analyzing expressions and
 ** for generating VDBE code that evaluates expressions in SQLite.
 **
-** $Id: expr.c,v 1.261 2006/06/13 04:11:44 danielk1977 Exp $
+** $Id: expr.c,v 1.262 2006/06/14 19:00:21 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -1489,7 +1489,7 @@ void sqlite3ExprCode(Parse *pParse, Expr *pExpr){
       }else if( pExpr->iColumn>=0 ){
         Table *pTab = pExpr->pTab;
         int iCol = pExpr->iColumn;
-        int op = (pTab && pTab->isVirtual) ? OP_VColumn : OP_Column;
+        int op = (pTab && IsVirtual(pTab)) ? OP_VColumn : OP_Column;
         sqlite3VdbeAddOp(v, op, pExpr->iTable, iCol);
         sqlite3ColumnDefault(v, pTab, iCol);
 #ifndef SQLITE_OMIT_FLOATING_POINT
@@ -1499,7 +1499,7 @@ void sqlite3ExprCode(Parse *pParse, Expr *pExpr){
 #endif
       }else{
         Table *pTab = pExpr->pTab;
-        int op = (pTab && pTab->isVirtual) ? OP_VRowid : OP_Rowid;
+        int op = (pTab && IsVirtual(pTab)) ? OP_VRowid : OP_Rowid;
         sqlite3VdbeAddOp(v, op, pExpr->iTable, 0);
       }
       break;
diff --git a/src/insert.c b/src/insert.c
index 295d753d3..3d34feda9 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle INSERT statements in SQLite.
 **
-** $Id: insert.c,v 1.165 2006/06/11 23:41:55 drh Exp $
+** $Id: insert.c,v 1.166 2006/06/14 19:00:21 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -567,6 +567,10 @@ void sqlite3Insert(
   ** case the record number is the same as that column. 
   */
   if( !isView ){
+    if( IsVirtual(pTab) ){
+      /* The row that the VUpdate opcode will delete:  none */
+      sqlite3VdbeAddOp(v, OP_Null, 0, 0);
+    }
     if( keyColumn>=0 ){
       if( useTempTable ){
         sqlite3VdbeAddOp(v, OP_Column, srcTab, keyColumn);
@@ -582,6 +586,8 @@ void sqlite3Insert(
       sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
       sqlite3VdbeAddOp(v, OP_NewRowid, base, counterMem);
       sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
+    }else if( IsVirtual(pTab) ){
+      sqlite3VdbeAddOp(v, OP_Null, 0, 0);
     }else{
       sqlite3VdbeAddOp(v, OP_NewRowid, base, counterMem);
     }
@@ -624,10 +630,18 @@ void sqlite3Insert(
     /* Generate code to check constraints and generate index keys and
     ** do the insertion.
     */
-    sqlite3GenerateConstraintChecks(pParse, pTab, base, 0, keyColumn>=0,
-                                   0, onError, endOfLoop);
-    sqlite3CompleteInsertion(pParse, pTab, base, 0,0,0,
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    if( IsVirtual(pTab) ){
+      sqlite3VdbeOp3(v, OP_VUpdate, 0, pTab->nCol+1,
+                     (const char*)pTab->pVtab, P3_VTAB);
+    }else
+#endif
+    {
+      sqlite3GenerateConstraintChecks(pParse, pTab, base, 0, keyColumn>=0,
+                                     0, onError, endOfLoop);
+      sqlite3CompleteInsertion(pParse, pTab, base, 0,0,0,
                             (triggers_exist & TRIGGER_AFTER)!=0 ? newIdx : -1);
+    }
   }
 
   /* Update the count of rows that are inserted
@@ -665,7 +679,7 @@ void sqlite3Insert(
     sqlite3VdbeResolveLabel(v, iCleanup);
   }
 
-  if( !triggers_exist ){
+  if( !triggers_exist && !IsVirtual(pTab) ){
     /* Close all tables opened */
     sqlite3VdbeAddOp(v, OP_Close, base, 0);
     for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
@@ -1105,9 +1119,13 @@ void sqlite3OpenTableAndIndices(
   int op           /* OP_OpenRead or OP_OpenWrite */
 ){
   int i;
-  int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  int iDb;
   Index *pIdx;
-  Vdbe *v = sqlite3GetVdbe(pParse);
+  Vdbe *v;
+
+  if( IsVirtual(pTab) ) return;
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  v = sqlite3GetVdbe(pParse);
   assert( v!=0 );
   sqlite3OpenTable(pParse, base, iDb, pTab, op);
   for(i=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 28ea1f73f..fcc147adf 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -11,7 +11,7 @@
 *************************************************************************
 ** Internal interface definitions for SQLite.
 **
-** @(#) $Id: sqliteInt.h,v 1.504 2006/06/13 15:36:07 drh Exp $
+** @(#) $Id: sqliteInt.h,v 1.505 2006/06/14 19:00:21 drh Exp $
 */
 #ifndef _SQLITEINT_H_
 #define _SQLITEINT_H_
@@ -694,7 +694,6 @@ struct Table {
   u8 hasPrimKey;   /* True if there exists a primary key */
   u8 keyConf;      /* What to do in case of uniqueness conflict on iPKey */
   u8 autoInc;      /* True if the integer primary key is autoincrement */
-  u8 isVirtual;    /* True if this is a virtual table */
   int nRef;          /* Number of pointers to this Table */
   Trigger *pTrigger; /* List of SQL triggers on this table */
   FKey *pFKey;       /* Linked list of all foreign keys in this table */
@@ -708,6 +707,7 @@ struct Table {
 #ifndef SQLITE_OMIT_VIRTUALTABLE
   sqlite3_module *pModule;  /* Pointer to the implementation of the module */
   sqlite3_vtab *pVtab;      /* Pointer to the module instance */
+  u8 isVirtual;             /* True if this is a virtual table */
   int nModuleArg;           /* Number of arguments to the module */
   char **azModuleArg;       /* Text of all module args. [0] is module name */
 #endif
@@ -715,6 +715,17 @@ struct Table {
 };
 
 /*
+** Test to see whether or not a table is a virtual table.  This is
+** done as a macro so that it will be optimized out when virtual
+** table support is omitted from the build.
+*/
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+#  define IsVirtual(X) ((X)->isVirtual)
+#else
+#  define IsVirtual(X) 0
+#endif
+
+/*
 ** Each foreign key constraint is an instance of the following structure.
 **
 ** A foreign key is associated with two tables.  The "from" table is
diff --git a/src/trigger.c b/src/trigger.c
index d670e527c..15992df38 100644
--- a/src/trigger.c
+++ b/src/trigger.c
@@ -103,6 +103,10 @@ void sqlite3BeginTrigger(
     /* The table does not exist. */
     goto trigger_cleanup;
   }
+  if( IsVirtual(pTab) ){
+    sqlite3ErrorMsg(pParse, "cannot create triggers on virtual tables");
+    goto trigger_cleanup;
+  }
 
   /* Check that the trigger name is not reserved and that no trigger of the
   ** specified name exists */
@@ -594,9 +598,10 @@ int sqlite3TriggersExist(
   int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
   ExprList *pChanges      /* Columns that change in an UPDATE statement */
 ){
-  Trigger *pTrigger = pTab->pTrigger;
+  Trigger *pTrigger;
   int mask = 0;
 
+  pTrigger = IsVirtual(pTab) ? 0 : pTab->pTrigger;
   while( pTrigger ){
     if( pTrigger->op==op && checkColumnOverLap(pTrigger->pColumns, pChanges) ){
       mask |= pTrigger->tr_tm;
diff --git a/src/update.c b/src/update.c
index f1662eb1a..bc2a27150 100644
--- a/src/update.c
+++ b/src/update.c
@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle UPDATE statements.
 **
-** $Id: update.c,v 1.124 2006/06/11 23:41:56 drh Exp $
+** $Id: update.c,v 1.125 2006/06/14 19:00:22 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -277,9 +277,9 @@ void sqlite3Update(
   pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
   if( pWInfo==0 ) goto update_cleanup;
 
-  /* Remember the index of every item to be updated.
+  /* Remember the rowid of every item to be updated.
   */
-  sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
+  sqlite3VdbeAddOp(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur, 0);
   sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);
 
   /* End the database scan loop.
@@ -358,7 +358,7 @@ void sqlite3Update(
     }
   }
 
-  if( !isView ){
+  if( !isView && !IsVirtual(pTab) ){
     /* 
     ** Open every index that needs updating.  Note that if any
     ** index could potentially invoke a REPLACE conflict resolution 
@@ -390,7 +390,7 @@ void sqlite3Update(
     /* Loop over every record that needs updating.  We have to load
     ** the old data for each record to be updated because some columns
     ** might not change and we will need to copy the old value.
-    ** Also, the old data is needed to delete the old index entires.
+    ** Also, the old data is needed to delete the old index entries.
     ** So make the cursor point at the old record.
     */
     if( !triggers_exist ){
@@ -444,6 +444,42 @@ void sqlite3Update(
     sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRowid, 1, -1);
   }
 
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( !isView && IsVirtual(pTab) ){
+    addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
+
+    /* If the record number will change, push the record number as it
+    ** will be after the update. (The old record number is currently
+    ** on top of the stack.)
+    */
+    if( chngRowid ){
+      sqlite3ExprCode(pParse, pRowidExpr);
+      sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
+    }else{
+      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
+    }
+
+    /* Compute new data for this record.  
+    */
+    for(i=0; i<pTab->nCol; i++){
+      if( i==pTab->iPKey ){
+        sqlite3VdbeAddOp(v, OP_Null, 0, 0);
+        continue;
+      }
+      j = aXRef[i];
+      if( j<0 ){
+        sqlite3VdbeAddOp(v, OP_VNoChange, 0, 0);
+      }else{
+        sqlite3ExprCode(pParse, pChanges->a[j].pExpr);
+      }
+    }
+
+    /* Make the update */
+    sqlite3VdbeOp3(v, OP_VUpdate, 0, pTab->nCol+2, 
+                      (const char*)pTab->pVtab, P3_VTAB);
+  }
+#endif /* SQLITE_OMIT_VIRTUAL */
+
   /* Increment the row counter 
   */
   if( db->flags & SQLITE_CountRows && !pParse->trigStack){
@@ -474,7 +510,7 @@ void sqlite3Update(
   sqlite3VdbeJumpHere(v, addr);
 
   /* Close all tables if there were no FOR EACH ROW triggers */
-  if( !triggers_exist ){
+  if( !triggers_exist && !IsVirtual(pTab) ){
     for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
       if( openAll || aIdxUsed[i] ){
         sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
diff --git a/src/vdbe.c b/src/vdbe.c
index 5757cdc8a..050ab337b 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -43,7 +43,7 @@
 ** in this file for details.  If in doubt, do not deviate from existing
 ** commenting and indentation practices when changing or adding code.
 **
-** $Id: vdbe.c,v 1.559 2006/06/14 13:03:24 danielk1977 Exp $
+** $Id: vdbe.c,v 1.560 2006/06/14 19:00:22 drh Exp $
 */
 #include "sqliteInt.h"
 #include "os.h"
@@ -4539,7 +4539,7 @@ case OP_TableLock: {        /* no-push */
 ** P3 is the name of a virtual table in database P1. Call the xCreate method
 ** for that table.
 */
-case OP_VCreate: {
+case OP_VCreate: {   /* no-push */
   rc = sqlite3VtabCallCreate(db, pOp->p1, pOp->p3, &p->zErrMsg);
   break;
 }
@@ -4551,7 +4551,7 @@ case OP_VCreate: {
 ** P3 is the name of a virtual table in database P1.  Call the xDestroy method
 ** of that table.
 */
-case OP_VDestroy: {
+case OP_VDestroy: {   /* no-push */
   rc = sqlite3VtabCallDestroy(db, pOp->p1, pOp->p3);
   break;
 }
@@ -4564,7 +4564,7 @@ case OP_VDestroy: {
 ** P1 is a cursor number.  This opcode opens a cursor to the virtual
 ** table and stores that cursor in P1.
 */
-case OP_VOpen: {
+case OP_VOpen: {   /* no-push */
   Cursor *pCur = 0;
   sqlite3_vtab_cursor *pVtabCursor = 0;
 
@@ -4610,7 +4610,7 @@ case OP_VOpen: {
 ** A jump is made to P2 if the result set after filtering would be 
 ** empty.
 */
-case OP_VFilter: {
+case OP_VFilter: {   /* no-push */
   int nArg;
 
   const sqlite3_module *pModule;
@@ -4725,7 +4725,7 @@ case OP_VColumn: {
 ** jump to instruction P2.  Or, if the virtual table has reached
 ** the end of its result set, then fall through to the next instruction.
 */
-case OP_VNext: {
+case OP_VNext: {   /* no-push */
   const sqlite3_module *pModule;
   int res = 0;
 
@@ -4756,6 +4756,22 @@ case OP_VNext: {
 }
 #endif /* SQLITE_OMIT_VIRTUALTABLE */
 
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/* Opcode: VNoChange * * *
+**
+** Push an entry onto the stack which says to the VUpdate command
+** that the corresponding column of the row should not be modified.
+*/
+case OP_VNoChange: {
+  pTos++;
+  pTos->flags = 0;
+  pTos->n = 0;
+  break;
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+
 #ifndef SQLITE_OMIT_VIRTUALTABLE
 /* Opcode: VUpdate * P2 P3
 **
@@ -4764,23 +4780,41 @@ case OP_VNext: {
 ** are taken from the stack to pass to the xUpdate invocation. The
 ** value on the top of the stack corresponds to the p2th element 
 ** of the argv array passed to xUpdate.
-*/
-case OP_VUpdate: {
+**
+** The xUpdate method will do a DELETE or an INSERT or both.
+** The argv[0] element (which corresponds to the P2-th element down
+** on the stack) is the rowid of a row to delete.  If argv[0] is
+** NULL then no deletion occurs.  The argv[1] element is the rowid
+** of the new row.  This can be NULL to have the virtual table
+** select the new rowid for itself.  The higher elements in the
+** stack are the values of columns in the new row.  if any argv[i]
+** where i>=2 is a NULL pointer (that is to say if argv[i]==NULL 
+** which is different from if sqlite3_value_type(argv[i])==SQLITE_NULL)
+** that means to preserve a copy of that element.  In other words,
+** copy the corresponding value from the argv[0] row into the new row.
+**
+** If P2==1 then no insert is performed.  argv[0] is the rowid of
+** a row to delete.
+*/
+case OP_VUpdate: {   /* no-push */
   sqlite3_vtab *pVtab = (sqlite3_vtab *)(pOp->p3);
   sqlite3_module *pModule = (sqlite3_module *)pVtab->pModule;
+  int nArg = pOp->p2;
+  assert( pOp->p3type==P3_VTAB );
   if( pModule->xUpdate==0 ){
-    sqlite3SetString(&p->zErrMsg, "Unsupported module operation: xUpdate", 0);
+    sqlite3SetString(&p->zErrMsg, "read-only table", 0);
     rc = SQLITE_ERROR;
   }else{
     int i;
     Mem **apArg = p->apArg;
-    int nArg = pOp->p1;
-    for(i = 0; i<nArg; i++){
-      apArg[i] = &pTos[i+1-nArg];
-      storeTypeInfo(apArg[i], 0);
+    Mem *pX = &pTos[1-nArg];
+    for(i = 0; i<nArg; i++, pX++){
+      apArg[i] = pX->flags ? storeTypeInfo(pX,0), pX : 0;
     }
     rc = pModule->xUpdate(pVtab, nArg, apArg);
   }
+  popStack(&pTos, nArg);
+  break;
 }
 #endif /* SQLITE_OMIT_VIRTUALTABLE */
 
diff --git a/src/where.c b/src/where.c
index d137d740f..3928c488a 100644
--- a/src/where.c
+++ b/src/where.c
@@ -16,7 +16,7 @@
 ** so is applicable.  Because this module is responsible for selecting
 ** indices, you might also think of this module as the "query optimizer".
 **
-** $Id: where.c,v 1.216 2006/06/13 23:51:35 drh Exp $
+** $Id: where.c,v 1.217 2006/06/14 19:00:22 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -1790,7 +1790,7 @@ WhereInfo *sqlite3WhereBegin(
       }
       assert( pTabItem->pTab );
 #ifndef SQLITE_OMIT_VIRTUALTABLE
-      if( pTabItem->pTab->isVirtual ){
+      if( IsVirtual(pTabItem->pTab) ){
         cost = bestVirtualIndex(pParse, &wc, pTabItem, notReady,
                                 ppOrderBy ? *ppOrderBy : 0, i==0,
                                 &pLevel->pIdxInfo);