SQLite

  int nInMul                      /* Number of iterations due to IN */
){
  sqlite3 *db;                    /* Database connection malloc context */
  WhereLoop *pNew;                /* Template WhereLoop under construction */
  WhereTerm *pTerm;               /* A WhereTerm under consideration */
  int eqTermMask;                 /* Valid equality operators */
  WhereScan scan;                 /* Iterator for WHERE terms */
  WhereLoop savedLoop;

  db = pBuilder->db;
  pNew = pBuilder->pNew;
  if( db->mallocFailed ) return;

  if( pProbe->tnum<=0 || (pSrc->jointype & JT_LEFT)!=0 ){
    eqTermMask = WO_EQ|WO_IN;
  }else{
    eqTermMask = WO_EQ|WO_IN|WO_ISNULL;
  }


  if( pNew->nEq<pProbe->nColumn ){
    int iCol;            /* Index of the column in the table */


    iCol = pProbe->aiColumn[pNew->nEq];
    pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, iCol,
                          eqTermMask, iCol>=0 ? pProbe : 0);
    savedLoop = *pNew;
    pNew->nEq++;
    pNew->nTerm++;
    for(; pTerm!=0; pTerm = whereScanNext(&scan)){
      pNew->aTerm[pNew->nEq-1] = pTerm;
      pNew->nOut = (double)(pProbe->aiRowEst[pNew->nEq] * nInMul);
      pNew->rSetup = (double)0;
      pNew->rRun = pNew->nOut;
      pNew->prereq = savedLoop.prereq | pTerm->prereqRight;
      if( pProbe->tnum<=0 ){
        pNew->wsFlags = savedLoop.wsFlags | WHERE_ROWID_EQ;
      }else{
        pNew->wsFlags = savedLoop.wsFlags | WHERE_COLUMN_EQ;
      }
      whereLoopInsert(pBuilder->pWInfo, pNew);
      if( pNew->nEq<pProbe->nColumn ){
        whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul);
      }

    }
    *pNew = savedLoop;
  }
}

/*
** Add all WhereLoop objects for the iTab-th table of the join.  That
** table is guaranteed to be a b-tree table, not a virtual table.
*/
static void whereLoopAddBtree(
  WhereLoopBuilder *pBuilder, /* WHERE clause information */
  int iTab,                   /* The table to process */
  Bitmask mExtra              /* Extra prerequesites for using this table */
){
  Index *pProbe;              /* An index we are evaluating */

  Index sPk;                  /* A fake index object for the primary key */
  tRowcnt aiRowEstPk[2];      /* The aiRowEst[] value for the sPk index */
  int aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
  struct SrcList_item *pSrc;  /* The FROM clause btree term to add */
  sqlite3 *db;                /* The database connection */
  WhereLoop *pNew;            /* Template WhereLoop object */

    }
    pProbe = &sPk;
  }

  /* Loop over all indices
  */
  for(; pProbe; pProbe=pProbe->pNext){
    WhereTerm **paTerm;
    pNew->prereq = mExtra;
    pNew->iTab = iTab;
    pNew->nEq = 0;
    pNew->nTerm = 0;
    paTerm = sqlite3DbRealloc(db, pNew->aTerm,
                              (pProbe->nColumn+1)*sizeof(pNew->aTerm[0]));
    if( paTerm==0 ) break;
    pNew->aTerm = paTerm;
    pNew->pIndex = pProbe;

    whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 1);

    /* If there was an INDEXED BY clause, then only that one index is
    ** considered. */
    if( pSrc->pIndex ) break;

  if( pDistinct && isDistinctRedundant(pParse, pTabList, sWBI.pWC, pDistinct) ){
    pDistinct = 0;
    pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
  }

  /* Construct the WhereLoop objects */
  WHERETRACE(("*** Optimizer Start ***\n"));
  whereLoopAddAll(&sWLB);

  /* Display all of the WhereLoop objects if wheretrace is enabled */
#if defined(SQLITE_DEBUG) \
    && (defined(SQLITE_TEST) || defined(SQLITE_ENABLE_WHERETRACE))
  if( sqlite3WhereTrace ){
    WhereLoop *p;
    int nb = 2*((nTabList+15)/16);
    for(p=pWInfo->pLoops; p; p=p->pNextLoop){
      struct SrcList_item *pItem = pTabList->a + p->iTab;
       Table *pTab = pItem->pTab;
      sqlite3DebugPrintf("%02d.%0*llx", p->iTab, nb, p->prereq);
      sqlite3DebugPrintf(" %5s",
                         pItem->zAlias ? pItem->zAlias : pTab->zName);
      if( p->pIndex ){
        sqlite3DebugPrintf(".%-5s %2d", p->pIndex->zName, p->nEq);
      }else{
        sqlite3DebugPrintf("%9s","");
      }
      sqlite3DebugPrintf(" fg %08x OB %d,%d N %2d",
                         p->wsFlags, p->iOb, p->nOb, p->nTerm);
      sqlite3DebugPrintf(" cost %.2g+%.2g,%.2g\n",
                         p->prereq, p->rSetup, p->rRun, p->nOut);
    }
  }
#endif

  /* Chose the best index to use for each table in the FROM clause.
  **