SQLite

** in buffer aList[], size nList bytes.
**
** If the isPoslist argument is true, then it is assumed that the doclist
** contains a position-list following each docid. Otherwise, it is assumed
** that the doclist is simply a list of docids stored as delta encoded 
** varints.
*/
static int fts3DoclistCountDocids(char *aList, int nList){
  int nDoc = 0;                   /* Return value */
  if( aList ){
    char *aEnd = &aList[nList];   /* Pointer to one byte after EOF */
    char *p = aList;              /* Cursor */








    while( p<aEnd ){
      nDoc++;
      while( (*p++)&0x80 );     /* Skip docid varint */
      fts3PoslistCopy(0, &p);   /* Skip over position list */

    }
  }

  return nDoc;
}

/*

    /* Determine if token pTC should be deferred. If not, update nDocEst. 
    **
    ** TODO: If there are performance regressions involving deferred tokens,
    ** this (the logic that selects the tokens to be deferred) is probably
    ** the bit that needs to change.
    */

    if( ii && pTC->nOvfl>=(nDocEst*nDocSize) ){
      /* The number of overflow pages to load for this (and therefore all
      ** subsequent) tokens is greater than the estimated number of pages 
      ** that will be loaded if all subsequent tokens are deferred.
      */
      Fts3PhraseToken *pToken = pTC->pToken;
      rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
      fts3SegReaderCursorFree(pToken->pSegcsr);
      pToken->pSegcsr = 0;
    }else if( ii==0 || pTC->pPhrase->nToken>1 ){
      /* Either this is the cheapest token in the entire query, or it is
      ** part of a multi-token phrase. Either way, the entire doclist will
      ** (eventually) be loaded into memory. It may as well be now. */
      Fts3PhraseToken *pToken = pTC->pToken;
      int nList = 0;
      char *pList = 0;
      rc = fts3TermSelect(pTab, pToken, pTC->iCol, &nList, &pList);
      assert( rc==SQLITE_OK || pList==0 );
      if( rc==SQLITE_OK ){
        fts3EvalPhraseMergeToken(pTab, pTC->pPhrase, pTC->iToken,pList,nList);
        nDocEst = fts3DoclistCountDocids(
            pTC->pPhrase->doclist.aAll, pTC->pPhrase->doclist.nAll
        );
      }

    }else {

      /* This token will not be deferred. And it will not be loaded into




      ** memory at this point either. So assume that it filters out 75% of
      ** the currently estimated number of documents. */
      nDocEst = 1 + (nDocEst/4);
    }
    pTC->pToken = 0;
  }

  return rc;
}