static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
  WhereLoop **ppPrev, *p;
  WhereInfo *pWInfo = pBuilder->pWInfo;
  sqlite3 *db = pWInfo->pParse->db;
  int rc;

  /* Stop the search once we hit the query planner search limit */
  if( pBuilder->iPlanLimit==0 ){
    WHERETRACE(0xffffffff,("=== query planner search limit reached ===\n"));
    if( pBuilder->pOrSet ) pBuilder->pOrSet->n = 0;
    return SQLITE_DONE;
  }
  pBuilder->iPlanLimit--;

  whereLoopAdjustCost(pWInfo->pLoops, pTemplate);

  /* If pBuilder->pOrSet is defined, then only keep track of the costs
  ** and prereqs.
  */
  if( pBuilder->pOrSet!=0 ){
    if( pTemplate->nLTerm ){
#if WHERETRACE_ENABLED
      u16 n = pBuilder->pOrSet->n;
      int x =
#endif
      whereOrInsert(pBuilder->pOrSet, pTemplate->prereq, pTemplate->rRun,
                                    pTemplate->nOut);
#if WHERETRACE_ENABLED /* 0x8 */
      if( sqlite3WhereTrace & 0x8 ){
        sqlite3DebugPrintf(x?"   or-%d:  ":"   or-X:  ", n);
        sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC);
      }
#endif
    }
    return SQLITE_OK;
  }

  /* Look for an existing WhereLoop to replace with pTemplate
  */
  ppPrev = whereLoopFindLesser(&pWInfo->pLoops, pTemplate);

  if( ppPrev==0 ){
    /* There already exists a WhereLoop on the list that is better
    ** than pTemplate, so just ignore pTemplate */
#if WHERETRACE_ENABLED /* 0x8 */
    if( sqlite3WhereTrace & 0x8 ){
      sqlite3DebugPrintf("   skip: ");
      sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC);
    }
#endif
    return SQLITE_OK;  
  }else{
    p = *ppPrev;
  }

  /* If we reach this point it means that either p[] should be overwritten
  ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new
  ** WhereLoop and insert it.
  */
#if WHERETRACE_ENABLED /* 0x8 */
  if( sqlite3WhereTrace & 0x8 ){
    if( p!=0 ){
      sqlite3DebugPrintf("replace: ");
      sqlite3WhereLoopPrint(p, pBuilder->pWC);
      sqlite3DebugPrintf("   with: ");
    }else{
      sqlite3DebugPrintf("    add: ");
    }
    sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC);
  }
#endif
  if( p==0 ){
    /* Allocate a new WhereLoop to add to the end of the list */
    *ppPrev = p = sqlite3DbMallocRawNN(db, sizeof(WhereLoop));
    if( p==0 ) return SQLITE_NOMEM_BKPT;
    whereLoopInit(p);
    p->pNextLoop = 0;
  }else{
    /* We will be overwriting WhereLoop p[].  But before we do, first
    ** go through the rest of the list and delete any other entries besides
    ** p[] that are also supplated by pTemplate */
    WhereLoop **ppTail = &p->pNextLoop;
    WhereLoop *pToDel;
    while( *ppTail ){
      ppTail = whereLoopFindLesser(ppTail, pTemplate);
      if( ppTail==0 ) break;
      pToDel = *ppTail;
      if( pToDel==0 ) break;
      *ppTail = pToDel->pNextLoop;
#if WHERETRACE_ENABLED /* 0x8 */
      if( sqlite3WhereTrace & 0x8 ){
        sqlite3DebugPrintf(" delete: ");
        sqlite3WhereLoopPrint(pToDel, pBuilder->pWC);
      }
#endif
      whereLoopDelete(db, pToDel);
    }
  }
  rc = whereLoopXfer(db, p, pTemplate);
  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
    Index *pIndex = p->u.btree.pIndex;
    if( pIndex && pIndex->idxType==SQLITE_IDXTYPE_IPK ){
      p->u.btree.pIndex = 0;
    }
  }
  return rc;
}
Unknown