where.c

sqlite数据库管理系统开放源码

      }
      pLevel->iMem = pParse->nMem++;
      cont = pLevel->cont = sqliteVdbeMakeLabel(v);
      sqliteVdbeAddOp(v, OP_NotNull, -nColumn, sqliteVdbeCurrentAddr(v)+3);
      sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
      sqliteVdbeAddOp(v, OP_Goto, 0, brk);
      sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0);
      sqliteAddIdxKeyType(v, pIdx);
      if( nColumn==pIdx->nColumn || pLevel->bRev ){
        sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
        testOp = OP_IdxGT;
      }else{
        sqliteVdbeAddOp(v, OP_Dup, 0, 0);
        sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
        sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
        testOp = OP_IdxGE;
      }
      if( pLevel->bRev ){
        /* Scan in reverse order */
        sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
        sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk);
        start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
        sqliteVdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk);
        pLevel->op = OP_Prev;
      }else{
        /* Scan in the forward order */
        sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
        start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
        sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
        pLevel->op = OP_Next;
      }
      sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
      sqliteVdbeAddOp(v, OP_IdxIsNull, nColumn, cont);
      sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
      if( i==pTabList->nSrc-1 && pushKey ){
        haveKey = 1;
      }else{
        sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
        haveKey = 0;
      }
      pLevel->p1 = pLevel->iCur;
      pLevel->p2 = start;
    }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){
      /* Case 3:  We have an inequality comparison against the ROWID field.
      */
      int testOp = OP_Noop;
      int start;

      brk = pLevel->brk = sqliteVdbeMakeLabel(v);
      cont = pLevel->cont = sqliteVdbeMakeLabel(v);
      if( iDirectGt[i]>=0 ){
        k = iDirectGt[i];
        assert( k<nExpr );
        assert( aExpr[k].p!=0 );
        assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
        if( aExpr[k].idxLeft==iCur ){
          sqliteExprCode(pParse, aExpr[k].p->pRight);
        }else{
          sqliteExprCode(pParse, aExpr[k].p->pLeft);
        }
        sqliteVdbeAddOp(v, OP_ForceInt,
          aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT, brk);
        sqliteVdbeAddOp(v, OP_MoveTo, iCur, brk);
        disableTerm(pLevel, &aExpr[k].p);
      }else{
        sqliteVdbeAddOp(v, OP_Rewind, iCur, brk);
      }
      if( iDirectLt[i]>=0 ){
        k = iDirectLt[i];
        assert( k<nExpr );
        assert( aExpr[k].p!=0 );
        assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
        if( aExpr[k].idxLeft==iCur ){
          sqliteExprCode(pParse, aExpr[k].p->pRight);
        }else{
          sqliteExprCode(pParse, aExpr[k].p->pLeft);
        }
        /* sqliteVdbeAddOp(v, OP_MustBeInt, 0, sqliteVdbeCurrentAddr(v)+1); */
        pLevel->iMem = pParse->nMem++;
        sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
        if( aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT ){
          testOp = OP_Ge;
        }else{
          testOp = OP_Gt;
        }
        disableTerm(pLevel, &aExpr[k].p);
      }
      start = sqliteVdbeCurrentAddr(v);
      pLevel->op = OP_Next;
      pLevel->p1 = iCur;
      pLevel->p2 = start;
      if( testOp!=OP_Noop ){
        sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
        sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
        sqliteVdbeAddOp(v, testOp, 0, brk);
      }
      haveKey = 0;
    }else if( pIdx==0 ){
      /* Case 4:  There is no usable index.  We must do a complete
      **          scan of the entire database table.
      */
      int start;

      brk = pLevel->brk = sqliteVdbeMakeLabel(v);
      cont = pLevel->cont = sqliteVdbeMakeLabel(v);
      sqliteVdbeAddOp(v, OP_Rewind, iCur, brk);
      start = sqliteVdbeCurrentAddr(v);
      pLevel->op = OP_Next;
      pLevel->p1 = iCur;
      pLevel->p2 = start;
      haveKey = 0;
    }else{
      /* Case 5: The WHERE clause term that refers to the right-most
      **         column of the index is an inequality.  For example, if
      **         the index is on (x,y,z) and the WHERE clause is of the
      **         form "x=5 AND y<10" then this case is used.  Only the
      **         right-most column can be an inequality - the rest must
      **         use the "==" operator.
      **
      **         This case is also used when there are no WHERE clause
      **         constraints but an index is selected anyway, in order
      **         to force the output order to conform to an ORDER BY.
      */
      int score = pLevel->score;
      int nEqColumn = score/8;
      int start;
      int leFlag, geFlag;
      int testOp;

      /* Evaluate the equality constraints
      */
      for(j=0; j<nEqColumn; j++){
        for(k=0; k<nExpr; k++){
          if( aExpr[k].p==0 ) continue;
          if( aExpr[k].idxLeft==iCur
             && aExpr[k].p->op==TK_EQ
             && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight 
             && aExpr[k].p->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqliteExprCode(pParse, aExpr[k].p->pRight);
            disableTerm(pLevel, &aExpr[k].p);
            break;
          }
          if( aExpr[k].idxRight==iCur
             && aExpr[k].p->op==TK_EQ
             && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
             && aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
          ){
            sqliteExprCode(pParse, aExpr[k].p->pLeft);
            disableTerm(pLevel, &aExpr[k].p);
            break;
          }
        }
      }

      /* Duplicate the equality term values because they will all be
      ** used twice: once to make the termination key and once to make the
      ** start key.
      */
      for(j=0; j<nEqColumn; j++){
        sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0);
      }

      /* Labels for the beginning and end of the loop
      */
      cont = pLevel->cont = sqliteVdbeMakeLabel(v);
      brk = pLevel->brk = sqliteVdbeMakeLabel(v);

      /* Generate the termination key.  This is the key value that
      ** will end the search.  There is no termination key if there
      ** are no equality terms and no "X<..." term.
      **
      ** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
      ** key computed here really ends up being the start key.
      */
      if( (score & 1)!=0 ){
        for(k=0; k<nExpr; k++){
          Expr *pExpr = aExpr[k].p;
          if( pExpr==0 ) continue;
          if( aExpr[k].idxLeft==iCur
             && (pExpr->op==TK_LT || pExpr->op==TK_LE)
             && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight 
             && pExpr->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqliteExprCode(pParse, pExpr->pRight);
            leFlag = pExpr->op==TK_LE;
            disableTerm(pLevel, &aExpr[k].p);
            break;
          }
          if( aExpr[k].idxRight==iCur
             && (pExpr->op==TK_GT || pExpr->op==TK_GE)
             && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
             && pExpr->pRight->iColumn==pIdx->aiColumn[j]
          ){
            sqliteExprCode(pParse, pExpr->pLeft);
            leFlag = pExpr->op==TK_GE;
            disableTerm(pLevel, &aExpr[k].p);
            break;
          }
        }
        testOp = OP_IdxGE;
      }else{
        testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
        leFlag = 1;
      }
      if( testOp!=OP_Noop ){
        int nCol = nEqColumn + (score & 1);
        pLevel->iMem = pParse->nMem++;
        sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3);
        sqliteVdbeAddOp(v, OP_Pop, nCol, 0);
        sqliteVdbeAddOp(v, OP_Goto, 0, brk);
        sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0);
        sqliteAddIdxKeyType(v, pIdx);
        if( leFlag ){
          sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
        }
        if( pLevel->bRev ){
          sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk);
        }else{
          sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
        }
      }else if( pLevel->bRev ){
        sqliteVdbeAddOp(v, OP_Last, pLevel->iCur, brk);
      }

      /* Generate the start key.  This is the key that defines the lower
      ** bound on the search.  There is no start key if there are no
      ** equality terms and if there is no "X>..." term.  In
      ** that case, generate a "Rewind" instruction in place of the
      ** start key search.
      **
      ** 2002-Dec-04: In the case of a reverse-order search, the so-called
      ** "start" key really ends up being used as the termination key.
      */
      if( (score & 2)!=0 ){
        for(k=0; k<nExpr; k++){
          Expr *pExpr = aExpr[k].p;
          if( pExpr==0 ) continue;
          if( aExpr[k].idxLeft==iCur
             && (pExpr->op==TK_GT || pExpr->op==TK_GE)
             && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight 
             && pExpr->pLeft->iColumn==pIdx->aiColumn[j]
          ){
            sqliteExprCode(pParse, pExpr->pRight);
            geFlag = pExpr->op==TK_GE;
            disableTerm(pLevel, &aExpr[k].p);
            break;
          }
          if( aExpr[k].idxRight==iCur
             && (pExpr->op==TK_LT || pExpr->op==TK_LE)
             && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
             && pExpr->pRight->iColumn==pIdx->aiColumn[j]
          ){
            sqliteExprCode(pParse, pExpr->pLeft);
            geFlag = pExpr->op==TK_LE;
            disableTerm(pLevel, &aExpr[k].p);
            break;
          }
        }
      }else{
        geFlag = 1;
      }
      if( nEqColumn>0 || (score&2)!=0 ){
        int nCol = nEqColumn + ((score&2)!=0);
        sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3);
        sqliteVdbeAddOp(v, OP_Pop, nCol, 0);
        sqliteVdbeAddOp(v, OP_Goto, 0, brk);
        sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0);
        sqliteAddIdxKeyType(v, pIdx);
        if( !geFlag ){
          sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
        }
        if( pLevel->bRev ){
          pLevel->iMem = pParse->nMem++;
          sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
          testOp = OP_IdxLT;
        }else{
          sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
        }
      }else if( pLevel->bRev ){
        testOp = OP_Noop;
      }else{
        sqliteVdbeAddOp(v, OP_Rewind, pLevel->iCur, brk);
      }

      /* Generate the the top of the loop.  If there is a termination
      ** key we have to test for that key and abort at the top of the
      ** loop.
      */
      start = sqliteVdbeCurrentAddr(v);
      if( testOp!=OP_Noop ){
        sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
        sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
      }
      sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
      sqliteVdbeAddOp(v, OP_IdxIsNull, nEqColumn + (score & 1), cont);
      sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
      if( i==pTabList->nSrc-1 && pushKey ){
        haveKey = 1;
      }else{
        sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
        haveKey = 0;
      }

      /* Record the instruction used to terminate the loop.
      */
      pLevel->op = pLevel->bRev ? OP_Prev : OP_Next;
      pLevel->p1 = pLevel->iCur;
      pLevel->p2 = start;
    }
    loopMask |= getMask(&maskSet, iCur);

    /* Insert code to test every subexpression that can be completely
    ** computed using the current set of tables.
    */
    for(j=0; j<nExpr; j++){
      if( aExpr[j].p==0 ) continue;
      if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
      if( pLevel->iLeftJoin && !ExprHasProperty(aExpr[j].p,EP_FromJoin) ){
        continue;
      }
      if( haveKey ){
        haveKey = 0;
        sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
      }
      sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
      aExpr[j].p = 0;
    }
    brk = cont;

    /* For a LEFT OUTER JOIN, generate code that will record the fact that
    ** at least one row of the right table has matched the left table.  
    */
    if( pLevel->iLeftJoin ){
      pLevel->top = sqliteVdbeCurrentAddr(v);
      sqliteVdbeAddOp(v, OP_Integer, 1, 0);
      sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
      for(j=0; j<nExpr; j++){
        if( aExpr[j].p==0 ) continue;
        if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
        if( haveKey ){
          /* Cannot happen.  "haveKey" can only be true if pushKey is true
          ** an pushKey can only be true for DELETE and UPDATE and there are
          ** no outer joins with DELETE and UPDATE.
          */
          haveKey = 0;
          sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
        }
        sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
        aExpr[j].p = 0;
      }
    }
  }
  pWInfo->iContinue = cont;
  if( pushKey && !haveKey ){
    sqliteVdbeAddOp(v, OP_Recno, pTabList->a[0].iCursor, 0);
  }
  freeMaskSet(&maskSet);
  return pWInfo;
}

/*
** Generate the end of the WHERE loop.  See comments on 
** sqliteWhereBegin() for additional information.
*/
void sqliteWhereEnd(WhereInfo *pWInfo){
  Vdbe *v = pWInfo->pParse->pVdbe;
  int i;
  WhereLevel *pLevel;
  SrcList *pTabList = pWInfo->pTabList;

  for(i=pTabList->nSrc-1; i>=0; i--){
    pLevel = &pWInfo->a[i];
    sqliteVdbeResolveLabel(v, pLevel->cont);
    if( pLevel->op!=OP_Noop ){
      sqliteVdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
    }
    sqliteVdbeResolveLabel(v, pLevel->brk);
    if( pLevel->inOp!=OP_Noop ){
      sqliteVdbeAddOp(v, pLevel->inOp, pLevel->inP1, pLevel->inP2);
    }
    if( pLevel->iLeftJoin ){
      int addr;
      addr = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iLeftJoin, 0);
      sqliteVdbeAddOp(v, OP_NotNull, 1, addr+4 + (pLevel->iCur>=0));
      sqliteVdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0);
      if( pLevel->iCur>=0 ){
        sqliteVdbeAddOp(v, OP_NullRow, pLevel->iCur, 0);
      }
      sqliteVdbeAddOp(v, OP_Goto, 0, pLevel->top);
    }
  }
  sqliteVdbeResolveLabel(v, pWInfo->iBreak);
  for(i=0; i<pTabList->nSrc; i++){
    Table *pTab = pTabList->a[i].pTab;
    assert( pTab!=0 );
    if( pTab->isTransient || pTab->pSelect ) continue;
    pLevel = &pWInfo->a[i];
    sqliteVdbeAddOp(v, OP_Close, pTabList->a[i].iCursor, 0);
    if( pLevel->pIdx!=0 ){
      sqliteVdbeAddOp(v, OP_Close, pLevel->iCur, 0);
    }
  }
#if 0  /* Never reuse a cursor */
  if( pWInfo->pParse->nTab==pWInfo->peakNTab ){
    pWInfo->pParse->nTab = pWInfo->savedNTab;
  }
#endif
  sqliteFree(pWInfo);
  return;
}