Index: ext/misc/json1.c
==================================================================
--- ext/misc/json1.c
+++ ext/misc/json1.c
@@ -169,10 +169,11 @@
   const char *zJson; /* Original JSON string */
   u32 *aUp;          /* Index of parent of each node */
   u8 oom;            /* Set to true if out of memory */
   u8 nErr;           /* Number of errors seen */
   u16 iDepth;        /* Nesting depth */
+  int nJson;         /* Length of the zJson string in bytes */
 };
 
 /*
 ** Maximum nesting depth of JSON for this implementation.
 **
@@ -410,10 +411,18 @@
   pParse->nNode = 0;
   pParse->nAlloc = 0;
   sqlite3_free(pParse->aUp);
   pParse->aUp = 0;
 }
+
+/*
+** Free a JsonParse object that was obtained from sqlite3_malloc().
+*/
+static void jsonParseFree(JsonParse *pParse){
+  jsonParseReset(pParse);
+  sqlite3_free(pParse);
+}
 
 /*
 ** Convert the JsonNode pNode into a pure JSON string and
 ** append to pOut.  Subsubstructure is also included.  Return
 ** the number of JsonNode objects that are encoded.
@@ -961,10 +970,53 @@
     return SQLITE_NOMEM;
   }
   jsonParseFillInParentage(pParse, 0, 0);
   return SQLITE_OK;
 }
+
+/*
+** Magic number used for the JSON parse cache in sqlite3_get_auxdata()
+*/
+#define JSON_CACHE_ID  (-429938)
+
+/*
+** Obtain a complete parse of the JSON found in the first argument
+** of the argv array.  Use the sqlite3_get_auxdata() cache for this
+** parse if it is available.  If the cache is not available or if it
+** is no longer valid, parse the JSON again and return the new parse,
+** and also register the new parse so that it will be available for
+** future sqlite3_get_auxdata() calls.
+*/
+static JsonParse *jsonParseCached(
+  sqlite3_context *pCtx,
+  sqlite3_value **argv
+){
+  const char *zJson = (const char*)sqlite3_value_text(argv[0]);
+  int nJson = sqlite3_value_bytes(argv[0]);
+  JsonParse *p;
+  if( zJson==0 ) return 0;
+  p = (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID);
+  if( p && p->nJson==nJson && memcmp(p->zJson,zJson,nJson)==0 ){
+    p->nErr = 0;
+    return p; /* The cached entry matches, so return it */
+  }
+  p = sqlite3_malloc( sizeof(*p) + nJson + 1 );
+  if( p==0 ){
+    sqlite3_result_error_nomem(pCtx);
+    return 0;
+  }
+  memset(p, 0, sizeof(*p));
+  p->zJson = (char*)&p[1];
+  memcpy((char*)p->zJson, zJson, nJson+1);
+  if( jsonParse(p, pCtx, p->zJson) ){
+    sqlite3_free(p);
+    return 0;
+  }
+  p->nJson = nJson;
+  sqlite3_set_auxdata(pCtx, JSON_CACHE_ID, p, (void(*)(void*))jsonParseFree);
+  return (JsonParse*)sqlite3_get_auxdata(pCtx, JSON_CACHE_ID);
+}
 
 /*
 ** Compare the OBJECT label at pNode against zKey,nKey.  Return true on
 ** a match.
 */
@@ -1327,33 +1379,34 @@
 static void jsonArrayLengthFunc(
   sqlite3_context *ctx,
   int argc,
   sqlite3_value **argv
 ){
-  JsonParse x;          /* The parse */
+  JsonParse *p;          /* The parse */
   sqlite3_int64 n = 0;
   u32 i;
   JsonNode *pNode;
 
-  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
-  assert( x.nNode );
+  p = jsonParseCached(ctx, argv);
+  if( p==0 ) return;
+  assert( p->nNode );
   if( argc==2 ){
     const char *zPath = (const char*)sqlite3_value_text(argv[1]);
-    pNode = jsonLookup(&x, zPath, 0, ctx);
+    pNode = jsonLookup(p, zPath, 0, ctx);
   }else{
-    pNode = x.aNode;
+    pNode = p->aNode;
   }
   if( pNode==0 ){
-    x.nErr = 1;
-  }else if( pNode->eType==JSON_ARRAY ){
+    return;
+  }
+  if( pNode->eType==JSON_ARRAY ){
     assert( (pNode->jnFlags & JNODE_APPEND)==0 );
     for(i=1; i<=pNode->n; n++){
       i += jsonNodeSize(&pNode[i]);
     }
   }
-  if( x.nErr==0 ) sqlite3_result_int64(ctx, n);
-  jsonParseReset(&x);
+  sqlite3_result_int64(ctx, n);
 }
 
 /*
 ** json_extract(JSON, PATH, ...)
 **
@@ -1365,24 +1418,25 @@
 static void jsonExtractFunc(
   sqlite3_context *ctx,
   int argc,
   sqlite3_value **argv
 ){
-  JsonParse x;          /* The parse */
+  JsonParse *p;          /* The parse */
   JsonNode *pNode;
   const char *zPath;
   JsonString jx;
   int i;
 
   if( argc<2 ) return;
-  if( jsonParse(&x, ctx, (const char*)sqlite3_value_text(argv[0])) ) return;
+  p = jsonParseCached(ctx, argv);
+  if( p==0 ) return;
   jsonInit(&jx, ctx);
   jsonAppendChar(&jx, '[');
   for(i=1; i<argc; i++){
     zPath = (const char*)sqlite3_value_text(argv[i]);
-    pNode = jsonLookup(&x, zPath, 0, ctx);
-    if( x.nErr ) break;
+    pNode = jsonLookup(p, zPath, 0, ctx);
+    if( p->nErr ) break;
     if( argc>2 ){
       jsonAppendSeparator(&jx);
       if( pNode ){
         jsonRenderNode(pNode, &jx, 0);
       }else{
@@ -1396,11 +1450,10 @@
     jsonAppendChar(&jx, ']');
     jsonResult(&jx);
     sqlite3_result_subtype(ctx, JSON_SUBTYPE);
   }
   jsonReset(&jx);
-  jsonParseReset(&x);
 }
 
 /* This is the RFC 7396 MergePatch algorithm.
 */
 static JsonNode *jsonMergePatch(

Index: src/sqlite.h.in
==================================================================
--- src/sqlite.h.in
+++ src/sqlite.h.in
@@ -4761,14 +4761,15 @@
 ** metadata associated with the pattern string.  
 ** Then as long as the pattern string remains the same,
 ** the compiled regular expression can be reused on multiple
 ** invocations of the same function.
 **
-** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
-** associated by the sqlite3_set_auxdata() function with the Nth argument
-** value to the application-defined function. ^If there is no metadata
-** associated with the function argument, this sqlite3_get_auxdata() interface
+** ^The sqlite3_get_auxdata(C,N) interface returns a pointer to the metadata
+** associated by the sqlite3_set_auxdata(C,N,P,X) function with the Nth argument
+** value to the application-defined function.  ^N is zero for the left-most
+** function argument.  ^If there is no metadata
+** associated with the function argument, the sqlite3_get_auxdata(C,N) interface
 ** returns a NULL pointer.
 **
 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
 ** argument of the application-defined function.  ^Subsequent
 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
@@ -4794,10 +4795,14 @@
 ** sqlite3_set_auxdata() has been called.
 **
 ** ^(In practice, metadata is preserved between function calls for
 ** function parameters that are compile-time constants, including literal
 ** values and [parameters] and expressions composed from the same.)^
+**
+** The value of the N parameter to these interfaces should be non-negative.
+** Future enhancements may make use of negative N values to define new
+** kinds of function caching behavior.
 **
 ** These routines must be called from the same thread in which
 ** the SQL function is running.
 */
 void *sqlite3_get_auxdata(sqlite3_context*, int N);

Index: src/vdbeapi.c
==================================================================
--- src/vdbeapi.c
+++ src/vdbeapi.c
@@ -802,10 +802,16 @@
 }
 
 /*
 ** Return the auxiliary data pointer, if any, for the iArg'th argument to
 ** the user-function defined by pCtx.
+**
+** The left-most argument is 0.
+**
+** Undocumented behavior:  If iArg is negative then access a cache of
+** auxiliary data pointers that is available to all functions within a
+** single prepared statement.  The iArg values must match.
 */
 void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
   AuxData *pAuxData;
 
   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
@@ -813,11 +819,11 @@
   if( pCtx->pVdbe==0 ) return 0;
 #else
   assert( pCtx->pVdbe!=0 );
 #endif
   for(pAuxData=pCtx->pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNextAux){
-    if( pAuxData->iAuxOp==pCtx->iOp && pAuxData->iAuxArg==iArg ){
+    if(  pAuxData->iAuxArg==iArg && (pAuxData->iAuxOp==pCtx->iOp || iArg<0) ){
       return pAuxData->pAux;
     }
   }
   return 0;
 }
@@ -824,10 +830,16 @@
 
 /*
 ** Set the auxiliary data pointer and delete function, for the iArg'th
 ** argument to the user-function defined by pCtx. Any previous value is
 ** deleted by calling the delete function specified when it was set.
+**
+** The left-most argument is 0.
+**
+** Undocumented behavior:  If iArg is negative then make the data available
+** to all functions within the current prepared statement using iArg as an
+** access code.
 */
 void sqlite3_set_auxdata(
   sqlite3_context *pCtx, 
   int iArg, 
   void *pAux, 
@@ -835,19 +847,20 @@
 ){
   AuxData *pAuxData;
   Vdbe *pVdbe = pCtx->pVdbe;
 
   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
-  if( iArg<0 ) goto failed;
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
   if( pVdbe==0 ) goto failed;
 #else
   assert( pVdbe!=0 );
 #endif
 
   for(pAuxData=pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNextAux){
-    if( pAuxData->iAuxOp==pCtx->iOp && pAuxData->iAuxArg==iArg ) break;
+    if( pAuxData->iAuxArg==iArg && (pAuxData->iAuxOp==pCtx->iOp || iArg<0) ){
+      break;
+    }
   }
   if( pAuxData==0 ){
     pAuxData = sqlite3DbMallocZero(pVdbe->db, sizeof(AuxData));
     if( !pAuxData ) goto failed;
     pAuxData->iAuxOp = pCtx->iOp;

Index: src/vdbeaux.c
==================================================================
--- src/vdbeaux.c
+++ src/vdbeaux.c
@@ -2966,11 +2966,12 @@
 */
 void sqlite3VdbeDeleteAuxData(sqlite3 *db, AuxData **pp, int iOp, int mask){
   while( *pp ){
     AuxData *pAux = *pp;
     if( (iOp<0)
-     || (pAux->iAuxOp==iOp 
+     || (pAux->iAuxOp==iOp
+          && pAux->iAuxArg>=0
           && (pAux->iAuxArg>31 || !(mask & MASKBIT32(pAux->iAuxArg))))
     ){
       testcase( pAux->iAuxArg==31 );
       if( pAux->xDeleteAux ){
         pAux->xDeleteAux(pAux->pAux);