Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -753,10 +753,30 @@
   assert( cursorHoldsMutex(pCur) );
   sqlite3_free(pCur->pKey);
   pCur->pKey = 0;
   pCur->eState = CURSOR_INVALID;
 }
+
+/*
+** This is a debugging routine designed to reveal the file (database or
+** wal file) that the page would be read from if it were reread at the 
+** current time. It returns the name of the file.
+*/
+static const char *btreePageOriginFile(MemPage *pPage){
+  return sqlite3PagerOrigin(pPage->pDbPage, 0);
+}
+
+/*
+** This is a debugging routine designed to reveal the byte offset that
+** the page would be read from (from either the database or wal file) if it
+** were reread at the current time. The byte offset is returned.
+*/
+static i64 btreePageOriginOffset(MemPage *pPage){
+  i64 iOffset = 0;
+  sqlite3PagerOrigin(pPage->pDbPage, &iOffset);
+  return iOffset;
+}
 
 /*
 ** In this version of BtreeMoveto, pKey is a packed index record
 ** such as is generated by the OP_MakeRecord opcode.  Unpack the
 ** record and then call BtreeMovetoUnpacked() to do the work.

Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -7599,7 +7599,34 @@
 int sqlite3PagerWalFramesize(Pager *pPager){
   assert( pPager->eState>=PAGER_READER );
   return sqlite3WalFramesize(pPager->pWal);
 }
 #endif
+
+/*
+** Return the name of the file (wal file or database file) that page
+** pPg would be read from if it were reread at this point. Also set
+** output parameter (*piOffset) to the offset within said file.
+*/
+const char *sqlite3PagerOrigin(DbPage *pPg, i64 *piOffset){
+  Pager *pPager = pPg->pPager;
+  Pgno pgno = pPg->pgno;
+
+  assert( pPager->eState>=PAGER_READER );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->hasHeldSharedLock==1 );
+
+  if( pagerUseWal(pPager) ){
+    u32 iFrame = 0;
+    int rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
+    if( rc!=SQLITE_OK ) return 0;
+    if( iFrame ){
+      if( piOffset ) *piOffset = (i64)(iFrame-1) * (pPager->pageSize + 24) + 32;
+      return (const char*)pPager->zWal;
+    }
+  }
+
+  if( piOffset ) *piOffset = (i64)pPager->pageSize * (i64)(pgno-1);
+  return (const char*)pPager->zFilename;
+}
 
 #endif /* SQLITE_OMIT_DISKIO */

Index: src/pager.h
==================================================================
--- src/pager.h
+++ src/pager.h
@@ -234,7 +234,9 @@
   void enable_simulated_io_errors(void);
 #else
 # define disable_simulated_io_errors()
 # define enable_simulated_io_errors()
 #endif
+
+const char *sqlite3PagerOrigin(DbPage *pPg, i64 *piOffset);
 
 #endif /* SQLITE_PAGER_H */