SQLite

  int i;
  struct SrcList_item *pItem;
  if( pList==0 ) return;
  for(pItem=pList->a, i=0; i<pList->nSrc; i++, pItem++){
    sqlite3DbFree(db, pItem->zDatabase);
    sqlite3DbFree(db, pItem->zName);
    sqlite3DbFree(db, pItem->zAlias);
    sqlite3DbFree(db, pItem->zIndexedBy);
    sqlite3DeleteTable(db, pItem->pTab);
    sqlite3SelectDelete(db, pItem->pSelect);
    sqlite3ExprDelete(db, pItem->pOn);
    sqlite3IdListDelete(db, pItem->pUsing);
  }
  sqlite3DbFree(db, pList);
}

** Add an INDEXED BY or NOT INDEXED clause to the most recently added 
** element of the source-list passed as the second argument.
*/
void sqlite3SrcListIndexedBy(Parse *pParse, SrcList *p, Token *pIndexedBy){
  assert( pIndexedBy!=0 );
  if( p && ALWAYS(p->nSrc>0) ){
    struct SrcList_item *pItem = &p->a[p->nSrc-1];
    assert( pItem->notIndexed==0 && pItem->zIndexedBy==0 );
    if( pIndexedBy->n==1 && !pIndexedBy->z ){
      /* A "NOT INDEXED" clause was supplied. See parse.y 
      ** construct "indexed_opt" for details. */
      pItem->notIndexed = 1;
    }else{
      pItem->zIndexedBy = sqlite3NameFromToken(pParse->db, pIndexedBy);
    }
  }
}

/*
** When building up a FROM clause in the parser, the join operator
** is initially attached to the left operand.  But the code generator

    pNewItem->jointype = pOldItem->jointype;
    pNewItem->iCursor = pOldItem->iCursor;
    pNewItem->addrFillSub = pOldItem->addrFillSub;
    pNewItem->regReturn = pOldItem->regReturn;
    pNewItem->isCorrelated = pOldItem->isCorrelated;
    pNewItem->viaCoroutine = pOldItem->viaCoroutine;
    pNewItem->isRecursive = pOldItem->isRecursive;
    pNewItem->zIndexedBy = sqlite3DbStrDup(db, pOldItem->zIndexedBy);
    pNewItem->notIndexed = pOldItem->notIndexed;
    pNewItem->pIndex = pOldItem->pIndex;
    pTab = pNewItem->pTab = pOldItem->pTab;
    if( pTab ){
      pTab->nRef++;
    }
    pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect, flags);

** If the source-list item passed as an argument was augmented with an
** INDEXED BY clause, then try to locate the specified index. If there
** was such a clause and the named index cannot be found, return 
** SQLITE_ERROR and leave an error in pParse. Otherwise, populate 
** pFrom->pIndex and return SQLITE_OK.
*/
int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
  if( pFrom->pTab && pFrom->zIndexedBy ){
    Table *pTab = pFrom->pTab;
    char *zIndexedBy = pFrom->zIndexedBy;
    Index *pIdx;
    for(pIdx=pTab->pIndex; 
        pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy); 
        pIdx=pIdx->pNext
    );
    if( !pIdx ){
      sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0);
      pParse->checkSchema = 1;
      return SQLITE_ERROR;
    }
    pFrom->pIndex = pIdx;
  }
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_EXPLAIN
    u8 iSelectId;     /* If pSelect!=0, the id of the sub-select in EQP */
#endif
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
    char *zIndexedBy; /* Identifier from "INDEXED BY <zIndex>" clause */
    Index *pIndex;    /* Index structure corresponding to zIndex, if any */
  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/

  
  pWInfo = pBuilder->pWInfo;
  if( pWInfo->wctrlFlags & WHERE_FORCE_TABLE ) return 0;
  assert( pWInfo->pTabList->nSrc>=1 );
  pItem = pWInfo->pTabList->a;
  pTab = pItem->pTab;
  if( IsVirtual(pTab) ) return 0;
  if( pItem->zIndexedBy ) return 0;
  iCur = pItem->iCursor;
  pWC = &pWInfo->sWC;
  pLoop = pBuilder->pNew;
  pLoop->wsFlags = 0;
  pLoop->nSkip = 0;
  pTerm = findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IS, 0);
  if( pTerm ){