Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -195,12 +195,14 @@
 
 WINBASEAPI LPVOID WINAPI MapViewOfFile(HANDLE, DWORD, DWORD, DWORD, SIZE_T);
 #endif /* SQLITE_OS_WINRT */
 
 /*
-** This file mapping API is common to both Win32 and WinRT.
+** These file mapping APIs are common to both Win32 and WinRT.
 */
+
+WINBASEAPI BOOL WINAPI FlushViewOfFile(LPCVOID, SIZE_T);
 WINBASEAPI BOOL WINAPI UnmapViewOfFile(LPCVOID);
 #endif /* SQLITE_WIN32_FILEMAPPING_API */
 
 /*
 ** Some Microsoft compilers lack this definition.
@@ -1081,10 +1083,19 @@
 #endif
 
 #define osUuidCreateSequential \
         ((RPC_STATUS(RPC_ENTRY*)(UUID*))aSyscall[78].pCurrent)
 
+#if !defined(SQLITE_NO_SYNC) && SQLITE_MAX_MMAP_SIZE>0
+  { "FlushViewOfFile",          (SYSCALL)FlushViewOfFile,        0 },
+#else
+  { "FlushViewOfFile",          (SYSCALL)0,                      0 },
+#endif
+
+#define osFlushViewOfFile \
+        ((BOOL(WINAPI*)(LPCVOID,SIZE_T))aSyscall[79].pCurrent)
+
 }; /* End of the overrideable system calls */
 
 /*
 ** This is the xSetSystemCall() method of sqlite3_vfs for all of the
 ** "win32" VFSes.  Return SQLITE_OK opon successfully updating the
@@ -2786,10 +2797,26 @@
 #ifdef SQLITE_NO_SYNC
   OSTRACE(("SYNC-NOP pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
            osGetCurrentProcessId(), pFile, pFile->h));
   return SQLITE_OK;
 #else
+#if SQLITE_MAX_MMAP_SIZE>0
+  if( pFile->pMapRegion ){
+    if( osFlushViewOfFile(pFile->pMapRegion, 0) ){
+      OSTRACE(("SYNC-MMAP pid=%lu, pFile=%p, pMapRegion=%p, "
+               "rc=SQLITE_OK\n", osGetCurrentProcessId(),
+               pFile, pFile->pMapRegion));
+    }else{
+      pFile->lastErrno = osGetLastError();
+      OSTRACE(("SYNC-MMAP pid=%lu, pFile=%p, pMapRegion=%p, "
+               "rc=SQLITE_IOERR_MMAP\n", osGetCurrentProcessId(),
+               pFile, pFile->pMapRegion));
+      return winLogError(SQLITE_IOERR_MMAP, pFile->lastErrno,
+                         "winSync1", pFile->zPath);
+    }
+  }
+#endif
   rc = osFlushFileBuffers(pFile->h);
   SimulateIOError( rc=FALSE );
   if( rc ){
     OSTRACE(("SYNC pid=%lu, pFile=%p, file=%p, rc=SQLITE_OK\n",
              osGetCurrentProcessId(), pFile, pFile->h));
@@ -2797,11 +2824,11 @@
   }else{
     pFile->lastErrno = osGetLastError();
     OSTRACE(("SYNC pid=%lu, pFile=%p, file=%p, rc=SQLITE_IOERR_FSYNC\n",
              osGetCurrentProcessId(), pFile, pFile->h));
     return winLogError(SQLITE_IOERR_FSYNC, pFile->lastErrno,
-                       "winSync", pFile->zPath);
+                       "winSync2", pFile->zPath);
   }
 #endif
 }
 
 /*
@@ -5571,11 +5598,11 @@
   };
 #endif
 
   /* Double-check that the aSyscall[] array has been constructed
   ** correctly.  See ticket [bb3a86e890c8e96ab] */
-  assert( ArraySize(aSyscall)==79 );
+  assert( ArraySize(aSyscall)==80 );
 
   /* get memory map allocation granularity */
   memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
 #if SQLITE_OS_WINRT
   osGetNativeSystemInfo(&winSysInfo);