SQLite

    /* If ORDER BY makes no difference in the output then neither does
    ** DISTINCT so it can be removed too. */
    sqlite3ExprListDelete(db, p->pOrderBy);
    p->pOrderBy = 0;
    p->selFlags &= ~SF_Distinct;
  }
  sqlite3SelectPrep(pParse, p, 0);


  if( pParse->nErr || db->mallocFailed ){
    goto select_end;
  }
  assert( p->pEList!=0 );
#if SELECTTRACE_ENABLED
  if( sqlite3SelectTrace & 0x104 ){
    SELECTTRACE(0x104,pParse,p, ("after name resolution:\n"));

    SELECTTRACE(0x104,pParse,p, ("after window rewrite:\n"));
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif
#endif /* SQLITE_OMIT_WINDOWFUNC */
  pTabList = p->pSrc;
  isAgg = (p->selFlags & SF_Aggregate)!=0;
  memset(&sSort, 0, sizeof(sSort));
  sSort.pOrderBy = p->pOrderBy;

  /* Try to various optimizations (flattening subqueries, and strength
  ** reduction of join operators) in the FROM clause up into the main query
  */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
  for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
    struct SrcList_item *pItem = &pTabList->a[i];

    Window *pMWin = p->pWin;      /* Master window object */
    Window *pWin;                 /* Window object iterator */

    p->pSrc = 0;
    p->pWhere = 0;
    p->pGroupBy = 0;
    p->pHaving = 0;

    /* Create the ORDER BY clause for the sub-select. This is the concatenation
    ** of the window PARTITION and ORDER BY clauses. Then, if this makes it
    ** redundant, remove the ORDER BY from the parent SELECT.  */
    pSort = sqlite3ExprListDup(db, pMWin->pPartition, 0);
    pSort = exprListAppendList(pParse, pSort, pMWin->pOrderBy);
    if( pSort && p->pOrderBy ){
      if( sqlite3ExprListCompare(pSort, p->pOrderBy, -1)==0 ){
        sqlite3ExprListDelete(db, p->pOrderBy);
        p->pOrderBy = 0;
      }
    }

    /* Assign a cursor number for the ephemeral table used to buffer rows.
    ** The OpenEphemeral instruction is coded later, after it is known how
    ** many columns the table will have.  */
    pMWin->iEphCsr = pParse->nTab++;

    selectWindowRewriteEList(pParse, pMWin, p->pEList, &pSublist);
    selectWindowRewriteEList(pParse, pMWin, p->pOrderBy, &pSublist);
    pMWin->nBufferCol = (pSublist ? pSublist->nExpr : 0);


    /* Append the PARTITION BY and ORDER BY expressions to the to the 
    ** sub-select expression list. They are required to figure out where 
    ** boundaries for partitions and sets of peer rows lie.  */


    pSublist = exprListAppendList(pParse, pSublist, pMWin->pPartition);

    pSublist = exprListAppendList(pParse, pSublist, pMWin->pOrderBy);

    /* Append the arguments passed to each window function to the
    ** sub-select expression list. Also allocate two registers for each
    ** window function - one for the accumulator, another for interim
    ** results.  */
    for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
      pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);