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Overview
Comment:Change the WITH RECURSIVE implementation to use a queue instead of a pair of tables. Add support for ORDER BY, LIMIT, and OFFSET on recursive queries.
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Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: b6cea42006910d590373e8f9e296d7672edb114b
User & Date: drh 2014-01-22 18:16:27
Context
2014-01-22
18:31
Fix harmless compiler warnings. check-in: dea2ca6a user: drh tags: trunk
18:16
Change the WITH RECURSIVE implementation to use a queue instead of a pair of tables. Add support for ORDER BY, LIMIT, and OFFSET on recursive queries. check-in: b6cea420 user: drh tags: trunk
18:07
Add support for LIMIT and OFFSET in a recursive query. Closed-Leaf check-in: 1945484e user: drh tags: cte-via-queue
17:43
Update the spellfix virtual table to optimize queries of the form "SELECT ... FROM tbl WHERE rowid=?". check-in: a0ba55ff user: dan tags: trunk
Changes
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Changes to src/select.c.

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}

/*
** Add code to implement the OFFSET
*/
static void codeOffset(
  Vdbe *v,          /* Generate code into this VM */
  Select *p,        /* The SELECT statement being coded */
  int iContinue     /* Jump here to skip the current record */
){
  if( p->iOffset && iContinue!=0 ){
    int addr;
    sqlite3VdbeAddOp2(v, OP_AddImm, p->iOffset, -1);
    addr = sqlite3VdbeAddOp1(v, OP_IfNeg, p->iOffset);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue);
    VdbeComment((v, "skip OFFSET records"));
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
................................................................................
  int addrTnct;   /* Address of OP_OpenEphemeral opcode for tabTnct */
};

/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab and nColumn are both zero, then the pEList expressions
** are evaluated in order to get the data for this row.  If nColumn>0
** then data is pulled from srcTab and pEList is used only to get the
** datatypes for each column.
*/
static void selectInnerLoop(
  Parse *pParse,          /* The parser context */
  Select *p,              /* The complete select statement being coded */
  ExprList *pEList,       /* List of values being extracted */
  int srcTab,             /* Pull data from this table */
  int nColumn,            /* Number of columns in the source table */
  ExprList *pOrderBy,     /* If not NULL, sort results using this key */
  DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
  SelectDest *pDest,      /* How to dispose of the results */
  int iContinue,          /* Jump here to continue with next row */
  int iBreak              /* Jump here to break out of the inner loop */
){
  Vdbe *v = pParse->pVdbe;
................................................................................
  int hasDistinct;        /* True if the DISTINCT keyword is present */
  int regResult;              /* Start of memory holding result set */
  int eDest = pDest->eDest;   /* How to dispose of results */
  int iParm = pDest->iSDParm; /* First argument to disposal method */
  int nResultCol;             /* Number of result columns */

  assert( v );
  if( NEVER(v==0) ) return;
  assert( pEList!=0 );
  hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
  if( pOrderBy==0 && !hasDistinct ){
    codeOffset(v, p, iContinue);
  }

  /* Pull the requested columns.
  */
  if( nColumn>0 ){
    nResultCol = nColumn;
  }else{
    nResultCol = pEList->nExpr;
  }
  if( pDest->iSdst==0 ){
    pDest->iSdst = pParse->nMem+1;
    pDest->nSdst = nResultCol;
    pParse->nMem += nResultCol;
  }else{ 
    assert( pDest->nSdst==nResultCol );
  }
  regResult = pDest->iSdst;
  if( nColumn>0 ){
    for(i=0; i<nColumn; i++){
      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);

    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    sqlite3ExprCodeExprList(pParse, pEList, regResult,
                            (eDest==SRT_Output)?SQLITE_ECEL_DUP:0);
  }
  nColumn = nResultCol;

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){
    assert( pEList!=0 );
    assert( pEList->nExpr==nColumn );
    switch( pDistinct->eTnctType ){
      case WHERE_DISTINCT_ORDERED: {
        VdbeOp *pOp;            /* No longer required OpenEphemeral instr. */
        int iJump;              /* Jump destination */
        int regPrev;            /* Previous row content */

        /* Allocate space for the previous row */
        regPrev = pParse->nMem+1;
        pParse->nMem += nColumn;

        /* Change the OP_OpenEphemeral coded earlier to an OP_Null
        ** sets the MEM_Cleared bit on the first register of the
        ** previous value.  This will cause the OP_Ne below to always
        ** fail on the first iteration of the loop even if the first
        ** row is all NULLs.
        */
        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
        pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
        pOp->opcode = OP_Null;
        pOp->p1 = 1;
        pOp->p2 = regPrev;

        iJump = sqlite3VdbeCurrentAddr(v) + nColumn;
        for(i=0; i<nColumn; i++){
          CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr);
          if( i<nColumn-1 ){
            sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
          }else{
            sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
          }
          sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
          sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
        }
        assert( sqlite3VdbeCurrentAddr(v)==iJump );
        sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nColumn-1);
        break;
      }

      case WHERE_DISTINCT_UNIQUE: {
        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
        break;
      }

      default: {
        assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
        codeDistinct(pParse, pDistinct->tabTnct, iContinue, nColumn, regResult);
        break;
      }
    }
    if( pOrderBy==0 ){
      codeOffset(v, p, iContinue);
    }
  }

  switch( eDest ){
    /* In this mode, write each query result to the key of the temporary
    ** table iParm.
    */
#ifndef SQLITE_OMIT_COMPOUND_SELECT
    case SRT_Union: {
      int r1;
      r1 = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
      sqlite3ReleaseTempReg(pParse, r1);
      break;
    }

    /* Construct a record from the query result, but instead of
    ** saving that record, use it as a key to delete elements from
    ** the temporary table iParm.
    */
    case SRT_Except: {
      sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nColumn);
      break;
    }
#endif

    /* Store the result as data using a unique key.
    */
    case SRT_DistTable:
    case SRT_Table:
    case SRT_EphemTab: {
      int r1 = sqlite3GetTempReg(pParse);
      testcase( eDest==SRT_Table );
      testcase( eDest==SRT_EphemTab );
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
#ifndef SQLITE_OMIT_CTE
      if( eDest==SRT_DistTable ){
        /* If the destination is DistTable, then cursor (iParm+1) is open
        ** on an ephemeral index. If the current row is already present
        ** in the index, do not write it to the output. If not, add the
        ** current row to the index and proceed with writing it to the
        ** output table as well.  */
................................................................................

#ifndef SQLITE_OMIT_SUBQUERY
    /* If we are creating a set for an "expr IN (SELECT ...)" construct,
    ** then there should be a single item on the stack.  Write this
    ** item into the set table with bogus data.
    */
    case SRT_Set: {
      assert( nColumn==1 );
      pDest->affSdst =
                  sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affSdst);
      if( pOrderBy ){
        /* At first glance you would think we could optimize out the
        ** ORDER BY in this case since the order of entries in the set
        ** does not matter.  But there might be a LIMIT clause, in which
        ** case the order does matter */
................................................................................
    }

    /* If this is a scalar select that is part of an expression, then
    ** store the results in the appropriate memory cell and break out
    ** of the scan loop.
    */
    case SRT_Mem: {
      assert( nColumn==1 );
      if( pOrderBy ){
        pushOntoSorter(pParse, pOrderBy, p, regResult);
      }else{
        sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
        /* The LIMIT clause will jump out of the loop for us */
      }
      break;
................................................................................
    */
    case SRT_Coroutine:
    case SRT_Output: {
      testcase( eDest==SRT_Coroutine );
      testcase( eDest==SRT_Output );
      if( pOrderBy ){
        int r1 = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
        pushOntoSorter(pParse, pOrderBy, p, r1);
        sqlite3ReleaseTempReg(pParse, r1);
      }else if( eDest==SRT_Coroutine ){
        sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
      }else{
        sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn);
        sqlite3ExprCacheAffinityChange(pParse, regResult, nColumn);
      }
      break;
    }














































#if !defined(SQLITE_OMIT_TRIGGER)
    /* Discard the results.  This is used for SELECT statements inside
    ** the body of a TRIGGER.  The purpose of such selects is to call
    ** user-defined functions that have side effects.  We do not care
    ** about the actual results of the select.
    */
................................................................................
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc.  The calling
** function is responsible for seeing that this structure is eventually
** freed.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
  int nExpr;
  KeyInfo *pInfo;
  struct ExprList_item *pItem;
  sqlite3 *db = pParse->db;
  int i;

  nExpr = pList->nExpr;
  pInfo = sqlite3KeyInfoAlloc(db, nExpr, 1);
  if( pInfo ){
    assert( sqlite3KeyInfoIsWriteable(pInfo) );
    for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
      CollSeq *pColl;
      pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
      if( !pColl ) pColl = db->pDfltColl;
      pInfo->aColl[i] = pColl;
................................................................................
    regRowid = sqlite3GetTempReg(pParse);
  }
  if( p->selFlags & SF_UseSorter ){
    int regSortOut = ++pParse->nMem;
    int ptab2 = pParse->nTab++;
    sqlite3VdbeAddOp3(v, OP_OpenPseudo, ptab2, regSortOut, pOrderBy->nExpr+2);
    addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
    codeOffset(v, p, addrContinue);
    sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut);
    sqlite3VdbeAddOp3(v, OP_Column, ptab2, pOrderBy->nExpr+1, regRow);
    sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
  }else{
    addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak);
    codeOffset(v, p, addrContinue);
    sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr+1, regRow);
  }
  switch( eDest ){
    case SRT_Table:
    case SRT_EphemTab: {
      testcase( eDest==SRT_Table );
      testcase( eDest==SRT_EphemTab );
................................................................................
** keywords.  Or NULL if those keywords are omitted. iLimit and iOffset 
** are the integer memory register numbers for counters used to compute 
** the limit and offset.  If there is no limit and/or offset, then 
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit and pOffset.  iLimit and
** iOffset should have been preset to appropriate default values
** (usually but not always -1) prior to calling this routine.





** Only if pLimit!=0 or pOffset!=0 do the limit registers get
** redefined.  The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
  Vdbe *v = 0;
................................................................................
  ** no rows.
  */
  sqlite3ExprCacheClear(pParse);
  assert( p->pOffset==0 || p->pLimit!=0 );
  if( p->pLimit ){
    p->iLimit = iLimit = ++pParse->nMem;
    v = sqlite3GetVdbe(pParse);
    if( NEVER(v==0) ) return;  /* VDBE should have already been allocated */
    if( sqlite3ExprIsInteger(p->pLimit, &n) ){
      sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
      VdbeComment((v, "LIMIT counter"));
      if( n==0 ){
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
      }else if( n>=0 && p->nSelectRow>(u64)n ){
        p->nSelectRow = n;
................................................................................
  if( pRet==0 && iCol<p->pEList->nExpr ){
    pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
  }
  return pRet;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */































































































































































/* Forward reference */
static int multiSelectOrderBy(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
);


................................................................................
    }
    rc = 1;
    goto multi_select_end;
  }

#ifndef SQLITE_OMIT_CTE
  if( p->selFlags & SF_Recursive ){
    SrcList *pSrc = p->pSrc;
    int nCol = p->pEList->nExpr;
    int addrNext;
    int addrSwap;
    int iCont, iBreak;
    int tmp1;                     /* Intermediate table */
    int tmp2;                     /* Next intermediate table */
    int tmp3 = 0;                 /* To ensure unique results if UNION */
    int eDest = SRT_Table;
    SelectDest tmp2dest;
    int i;

    /* Check that there is no ORDER BY or LIMIT clause. Neither of these 
    ** are supported on recursive queries.  */
    assert( p->pOffset==0 || p->pLimit );
    if( p->pOrderBy || p->pLimit ){
      sqlite3ErrorMsg(pParse, "%s in a recursive query",
          p->pOrderBy ? "ORDER BY" : "LIMIT"
      );
      goto multi_select_end;
    }

    if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ){
      goto multi_select_end;
    }
    iBreak = sqlite3VdbeMakeLabel(v);
    iCont = sqlite3VdbeMakeLabel(v);

    for(i=0; ALWAYS(i<pSrc->nSrc); i++){
      if( pSrc->a[i].isRecursive ){
        tmp1 = pSrc->a[i].iCursor;
        break;
      }
    }

    tmp2 = pParse->nTab++;
    if( p->op==TK_UNION ){
      eDest = SRT_DistTable;
      tmp3 = pParse->nTab++;
    }
    sqlite3SelectDestInit(&tmp2dest, eDest, tmp2);

    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tmp1, nCol);
    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tmp2, nCol);
    if( tmp3 ){
      p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tmp3, 0);
      p->selFlags |= SF_UsesEphemeral;
    }

    /* Store the results of the initial SELECT in tmp2. */
    rc = sqlite3Select(pParse, pPrior, &tmp2dest);
    if( rc ) goto multi_select_end;

    /* Clear tmp1. Then switch the contents of tmp1 and tmp2. Then return 
    ** the contents of tmp1 to the caller. Or, if tmp1 is empty at this
    ** point, the recursive query has finished - jump to address iBreak.  */
    addrSwap = sqlite3VdbeAddOp2(v, OP_SwapCursors, tmp1, tmp2);
    sqlite3VdbeAddOp2(v, OP_Rewind, tmp1, iBreak);
    addrNext = sqlite3VdbeCurrentAddr(v);
    selectInnerLoop(pParse, p, p->pEList, tmp1, p->pEList->nExpr,
        0, 0, &dest, iCont, iBreak);
    sqlite3VdbeResolveLabel(v, iCont);
    sqlite3VdbeAddOp2(v, OP_Next, tmp1, addrNext);

    /* Execute the recursive SELECT. Store the results in tmp2. While this
    ** SELECT is running, the contents of tmp1 are read by recursive 
    ** references to the current CTE.  */
    p->pPrior = 0;
    rc = sqlite3Select(pParse, p, &tmp2dest);
    assert( p->pPrior==0 );
    p->pPrior = pPrior;
    if( rc ) goto multi_select_end;

    sqlite3VdbeAddOp2(v, OP_Goto, 0, addrSwap);
    sqlite3VdbeResolveLabel(v, iBreak);
  }else
#endif

  /* Compound SELECTs that have an ORDER BY clause are handled separately.
  */
  if( p->pOrderBy ){
    return multiSelectOrderBy(pParse, p, pDest);
................................................................................
          generateColumnNames(pParse, 0, pFirst->pEList);
        }
        iBreak = sqlite3VdbeMakeLabel(v);
        iCont = sqlite3VdbeMakeLabel(v);
        computeLimitRegisters(pParse, p, iBreak);
        sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak);
        iStart = sqlite3VdbeCurrentAddr(v);
        selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
                        0, 0, &dest, iCont, iBreak);
        sqlite3VdbeResolveLabel(v, iCont);
        sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart);
        sqlite3VdbeResolveLabel(v, iBreak);
        sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
      }
      break;
................................................................................
      iCont = sqlite3VdbeMakeLabel(v);
      computeLimitRegisters(pParse, p, iBreak);
      sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak);
      r1 = sqlite3GetTempReg(pParse);
      iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1);
      sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0);
      sqlite3ReleaseTempReg(pParse, r1);
      selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
                      0, 0, &dest, iCont, iBreak);
      sqlite3VdbeResolveLabel(v, iCont);
      sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart);
      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
................................................................................
    sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1);
    sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
  }
  if( pParse->db->mallocFailed ) return 0;

  /* Suppress the first OFFSET entries if there is an OFFSET clause
  */
  codeOffset(v, p, iContinue);

  switch( pDest->eDest ){
    /* Store the result as data using a unique key.
    */
    case SRT_Table:
    case SRT_EphemTab: {
      int r1 = sqlite3GetTempReg(pParse);
................................................................................
      Expr *pE = pFunc->pExpr;
      assert( !ExprHasProperty(pE, EP_xIsSelect) );
      if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
           "argument");
        pFunc->iDistinct = -1;
      }else{
        KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList);
        sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
                          (char*)pKeyInfo, P4_KEYINFO);
      }
    }
  }
}

................................................................................
#else
# define explainSimpleCount(a,b,c)
#endif

/*
** Generate code for the SELECT statement given in the p argument.  
**
** The results are distributed in various ways depending on the
** contents of the SelectDest structure pointed to by argument pDest
** as follows:
**
**     pDest->eDest    Result
**     ------------    -------------------------------------------
**     SRT_Output      Generate a row of output (using the OP_ResultRow
**                     opcode) for each row in the result set.
**
**     SRT_Mem         Only valid if the result is a single column.
**                     Store the first column of the first result row
**                     in register pDest->iSDParm then abandon the rest
**                     of the query.  This destination implies "LIMIT 1".
**
**     SRT_Set         The result must be a single column.  Store each
**                     row of result as the key in table pDest->iSDParm. 
**                     Apply the affinity pDest->affSdst before storing
**                     results.  Used to implement "IN (SELECT ...)".
**
**     SRT_Union       Store results as a key in a temporary table 
**                     identified by pDest->iSDParm.
**
**     SRT_Except      Remove results from the temporary table pDest->iSDParm.
**
**     SRT_Table       Store results in temporary table pDest->iSDParm.
**                     This is like SRT_EphemTab except that the table
**                     is assumed to already be open.
**
**     SRT_EphemTab    Create an temporary table pDest->iSDParm and store
**                     the result there. The cursor is left open after
**                     returning.  This is like SRT_Table except that
**                     this destination uses OP_OpenEphemeral to create
**                     the table first.
**
**     SRT_Coroutine   Generate a co-routine that returns a new row of
**                     results each time it is invoked.  The entry point
**                     of the co-routine is stored in register pDest->iSDParm.
**
**     SRT_Exists      Store a 1 in memory cell pDest->iSDParm if the result
**                     set is not empty.
**
**     SRT_Discard     Throw the results away.  This is used by SELECT
**                     statements within triggers whose only purpose is
**                     the side-effects of functions.
**
** This routine returns the number of errors.  If any errors are
** encountered, then an appropriate error message is left in
** pParse->zErrMsg.
**
** This routine does NOT free the Select structure passed in.  The
** calling function needs to do that.
................................................................................
  ** extracted in pre-sorted order.  If that is the case, then the
  ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
  ** we figure out that the sorting index is not needed.  The addrSortIndex
  ** variable is used to facilitate that change.
  */
  if( pOrderBy ){
    KeyInfo *pKeyInfo;
    pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
    pOrderBy->iECursor = pParse->nTab++;
    p->addrOpenEphm[2] = addrSortIndex =
      sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                           pOrderBy->iECursor, pOrderBy->nExpr+2, 0,
                           (char*)pKeyInfo, P4_KEYINFO);
  }else{
    addrSortIndex = -1;
................................................................................

  /* Open a virtual index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    sDistinct.tabTnct = pParse->nTab++;
    sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                                sDistinct.tabTnct, 0, 0,
                                (char*)keyInfoFromExprList(pParse, p->pEList),
                                P4_KEYINFO);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

................................................................................
    */
    if( addrSortIndex>=0 && pOrderBy==0 ){
      sqlite3VdbeChangeToNoop(v, addrSortIndex);
      p->addrOpenEphm[2] = -1;
    }

    /* Use the standard inner loop. */
    selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, &sDistinct, pDest,
                    sqlite3WhereContinueLabel(pWInfo),
                    sqlite3WhereBreakLabel(pWInfo));

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);
  }else{
................................................................................

      /* If there is a GROUP BY clause we might need a sorting index to
      ** implement it.  Allocate that sorting index now.  If it turns out
      ** that we do not need it after all, the OP_SorterOpen instruction
      ** will be converted into a Noop.  
      */
      sAggInfo.sortingIdx = pParse->nTab++;
      pKeyInfo = keyInfoFromExprList(pParse, pGroupBy);
      addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, 
          sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 
          0, (char*)pKeyInfo, P4_KEYINFO);

      /* Initialize memory locations used by GROUP BY aggregate processing
      */
      iUseFlag = ++pParse->nMem;
................................................................................
      sqlite3VdbeResolveLabel(v, addrOutputRow);
      addrOutputRow = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
      VdbeComment((v, "Groupby result generator entry point"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      finalizeAggFunctions(pParse, &sAggInfo);
      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
                      &sDistinct, pDest,
                      addrOutputRow+1, addrSetAbort);
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      VdbeComment((v, "end groupby result generator"));

      /* Generate a subroutine that will reset the group-by accumulator
      */
................................................................................
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);
      }

      pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, 0, 
                      pDest, addrEnd, addrEnd);
      sqlite3ExprListDelete(db, pDel);
    }
    sqlite3VdbeResolveLabel(v, addrEnd);
    
  } /* endif aggregate query */








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458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
...
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555

556
557
558
559
560
561
562
...
564
565
566
567
568
569
570

571
572
573
574
575
576
577
578



579

580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599

600
601
602
603
604
605


606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
...
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
...
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
...
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
...
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
....
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
....
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
....
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
....
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
....
1988
1989
1990
1991
1992
1993
1994
1995










































































1996
1997
1998
1999
2000
2001
2002
....
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
....
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
....
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
....
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
....
4410
4411
4412
4413
4414
4415
4416
4417
4418










































4419
4420
4421
4422
4423
4424
4425
....
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
....
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
....
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
....
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
....
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
....
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
}

/*
** Add code to implement the OFFSET
*/
static void codeOffset(
  Vdbe *v,          /* Generate code into this VM */
  int iOffset,      /* Register holding the offset counter */
  int iContinue     /* Jump here to skip the current record */
){
  if( iOffset>0 && iContinue!=0 ){
    int addr;
    sqlite3VdbeAddOp2(v, OP_AddImm, iOffset, -1);
    addr = sqlite3VdbeAddOp1(v, OP_IfNeg, iOffset);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue);
    VdbeComment((v, "skip OFFSET records"));
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
................................................................................
  int addrTnct;   /* Address of OP_OpenEphemeral opcode for tabTnct */
};

/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab is negative, then the pEList expressions
** are evaluated in order to get the data for this row.  If srcTab is
** zero or more, then data is pulled from srcTab and pEList is used only 
** to get number columns and the datatype for each column.
*/
static void selectInnerLoop(
  Parse *pParse,          /* The parser context */
  Select *p,              /* The complete select statement being coded */
  ExprList *pEList,       /* List of values being extracted */
  int srcTab,             /* Pull data from this table */

  ExprList *pOrderBy,     /* If not NULL, sort results using this key */
  DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
  SelectDest *pDest,      /* How to dispose of the results */
  int iContinue,          /* Jump here to continue with next row */
  int iBreak              /* Jump here to break out of the inner loop */
){
  Vdbe *v = pParse->pVdbe;
................................................................................
  int hasDistinct;        /* True if the DISTINCT keyword is present */
  int regResult;              /* Start of memory holding result set */
  int eDest = pDest->eDest;   /* How to dispose of results */
  int iParm = pDest->iSDParm; /* First argument to disposal method */
  int nResultCol;             /* Number of result columns */

  assert( v );

  assert( pEList!=0 );
  hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
  if( pOrderBy==0 && !hasDistinct ){
    codeOffset(v, p->iOffset, iContinue);
  }

  /* Pull the requested columns.
  */



  nResultCol = pEList->nExpr;

  if( pDest->iSdst==0 ){
    pDest->iSdst = pParse->nMem+1;
    pDest->nSdst = nResultCol;
    pParse->nMem += nResultCol;
  }else{ 
    assert( pDest->nSdst==nResultCol );
  }
  regResult = pDest->iSdst;
  if( srcTab>=0 ){
    for(i=0; i<nResultCol; i++){
      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
      VdbeComment((v, "%s", pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    sqlite3ExprCodeExprList(pParse, pEList, regResult,
                            (eDest==SRT_Output)?SQLITE_ECEL_DUP:0);
  }


  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){


    switch( pDistinct->eTnctType ){
      case WHERE_DISTINCT_ORDERED: {
        VdbeOp *pOp;            /* No longer required OpenEphemeral instr. */
        int iJump;              /* Jump destination */
        int regPrev;            /* Previous row content */

        /* Allocate space for the previous row */
        regPrev = pParse->nMem+1;
        pParse->nMem += nResultCol;

        /* Change the OP_OpenEphemeral coded earlier to an OP_Null
        ** sets the MEM_Cleared bit on the first register of the
        ** previous value.  This will cause the OP_Ne below to always
        ** fail on the first iteration of the loop even if the first
        ** row is all NULLs.
        */
        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
        pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
        pOp->opcode = OP_Null;
        pOp->p1 = 1;
        pOp->p2 = regPrev;

        iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
        for(i=0; i<nResultCol; i++){
          CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr);
          if( i<nResultCol-1 ){
            sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
          }else{
            sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
          }
          sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
          sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
        }
        assert( sqlite3VdbeCurrentAddr(v)==iJump );
        sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nResultCol-1);
        break;
      }

      case WHERE_DISTINCT_UNIQUE: {
        sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
        break;
      }

      default: {
        assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
        codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol, regResult);
        break;
      }
    }
    if( pOrderBy==0 ){
      codeOffset(v, p->iOffset, iContinue);
    }
  }

  switch( eDest ){
    /* In this mode, write each query result to the key of the temporary
    ** table iParm.
    */
#ifndef SQLITE_OMIT_COMPOUND_SELECT
    case SRT_Union: {
      int r1;
      r1 = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
      sqlite3ReleaseTempReg(pParse, r1);
      break;
    }

    /* Construct a record from the query result, but instead of
    ** saving that record, use it as a key to delete elements from
    ** the temporary table iParm.
    */
    case SRT_Except: {
      sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol);
      break;
    }
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

    /* Store the result as data using a unique key.
    */
    case SRT_DistTable:
    case SRT_Table:
    case SRT_EphemTab: {
      int r1 = sqlite3GetTempReg(pParse);
      testcase( eDest==SRT_Table );
      testcase( eDest==SRT_EphemTab );
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
#ifndef SQLITE_OMIT_CTE
      if( eDest==SRT_DistTable ){
        /* If the destination is DistTable, then cursor (iParm+1) is open
        ** on an ephemeral index. If the current row is already present
        ** in the index, do not write it to the output. If not, add the
        ** current row to the index and proceed with writing it to the
        ** output table as well.  */
................................................................................

#ifndef SQLITE_OMIT_SUBQUERY
    /* If we are creating a set for an "expr IN (SELECT ...)" construct,
    ** then there should be a single item on the stack.  Write this
    ** item into the set table with bogus data.
    */
    case SRT_Set: {
      assert( nResultCol==1 );
      pDest->affSdst =
                  sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affSdst);
      if( pOrderBy ){
        /* At first glance you would think we could optimize out the
        ** ORDER BY in this case since the order of entries in the set
        ** does not matter.  But there might be a LIMIT clause, in which
        ** case the order does matter */
................................................................................
    }

    /* If this is a scalar select that is part of an expression, then
    ** store the results in the appropriate memory cell and break out
    ** of the scan loop.
    */
    case SRT_Mem: {
      assert( nResultCol==1 );
      if( pOrderBy ){
        pushOntoSorter(pParse, pOrderBy, p, regResult);
      }else{
        sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
        /* The LIMIT clause will jump out of the loop for us */
      }
      break;
................................................................................
    */
    case SRT_Coroutine:
    case SRT_Output: {
      testcase( eDest==SRT_Coroutine );
      testcase( eDest==SRT_Output );
      if( pOrderBy ){
        int r1 = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
        pushOntoSorter(pParse, pOrderBy, p, r1);
        sqlite3ReleaseTempReg(pParse, r1);
      }else if( eDest==SRT_Coroutine ){
        sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
      }else{
        sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol);
        sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol);
      }
      break;
    }

#ifndef SQLITE_OMIT_CTE
    /* Write the results into a priority queue that is order according to
    ** pDest->pOrderBy (in pSO).  pDest->iSDParm (in iParm) is the cursor for an
    ** index with pSO->nExpr+2 columns.  Build a key using pSO for the first
    ** pSO->nExpr columns, then make sure all keys are unique by adding a
    ** final OP_Sequence column.  The last column is the record as a blob.
    */
    case SRT_DistQueue:
    case SRT_Queue: {
      int nKey;
      int r1, r2, r3;
      int addrTest = 0;
      ExprList *pSO;
      pSO = pDest->pOrderBy;
      assert( pSO );
      nKey = pSO->nExpr;
      r1 = sqlite3GetTempReg(pParse);
      r2 = sqlite3GetTempRange(pParse, nKey+2);
      r3 = r2+nKey+1;
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3);
      if( eDest==SRT_DistQueue ){
        /* If the destination is DistQueue, then cursor (iParm+1) is open
        ** on a second ephemeral index that holds all values every previously
        ** added to the queue.  Only add this new value if it has never before
        ** been added */
        addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0, r3, 0);
        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3);
      }
      for(i=0; i<nKey; i++){
        sqlite3VdbeAddOp2(v, OP_SCopy,
                          regResult + pSO->a[i].u.x.iOrderByCol - 1,
                          r2+i);
      }
      sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1);
      sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
      if( addrTest ) sqlite3VdbeJumpHere(v, addrTest);
      sqlite3ReleaseTempReg(pParse, r1);
      sqlite3ReleaseTempRange(pParse, r2, nKey+2);
      break;
    }
#endif /* SQLITE_OMIT_CTE */



#if !defined(SQLITE_OMIT_TRIGGER)
    /* Discard the results.  This is used for SELECT statements inside
    ** the body of a TRIGGER.  The purpose of such selects is to call
    ** user-defined functions that have side effects.  We do not care
    ** about the actual results of the select.
    */
................................................................................
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc.  The calling
** function is responsible for seeing that this structure is eventually
** freed.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList, int nExtra){
  int nExpr;
  KeyInfo *pInfo;
  struct ExprList_item *pItem;
  sqlite3 *db = pParse->db;
  int i;

  nExpr = pList->nExpr;
  pInfo = sqlite3KeyInfoAlloc(db, nExpr+nExtra, 1);
  if( pInfo ){
    assert( sqlite3KeyInfoIsWriteable(pInfo) );
    for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
      CollSeq *pColl;
      pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
      if( !pColl ) pColl = db->pDfltColl;
      pInfo->aColl[i] = pColl;
................................................................................
    regRowid = sqlite3GetTempReg(pParse);
  }
  if( p->selFlags & SF_UseSorter ){
    int regSortOut = ++pParse->nMem;
    int ptab2 = pParse->nTab++;
    sqlite3VdbeAddOp3(v, OP_OpenPseudo, ptab2, regSortOut, pOrderBy->nExpr+2);
    addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
    codeOffset(v, p->iOffset, addrContinue);
    sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut);
    sqlite3VdbeAddOp3(v, OP_Column, ptab2, pOrderBy->nExpr+1, regRow);
    sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
  }else{
    addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak);
    codeOffset(v, p->iOffset, addrContinue);
    sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr+1, regRow);
  }
  switch( eDest ){
    case SRT_Table:
    case SRT_EphemTab: {
      testcase( eDest==SRT_Table );
      testcase( eDest==SRT_EphemTab );
................................................................................
** keywords.  Or NULL if those keywords are omitted. iLimit and iOffset 
** are the integer memory register numbers for counters used to compute 
** the limit and offset.  If there is no limit and/or offset, then 
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit and pOffset.  iLimit and
** iOffset should have been preset to appropriate default values (zero)
** prior to calling this routine.
**
** The iOffset register (if it exists) is initialized to the value
** of the OFFSET.  The iLimit register is initialized to LIMIT.  Register
** iOffset+1 is initialized to LIMIT+OFFSET.
**
** Only if pLimit!=0 or pOffset!=0 do the limit registers get
** redefined.  The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
  Vdbe *v = 0;
................................................................................
  ** no rows.
  */
  sqlite3ExprCacheClear(pParse);
  assert( p->pOffset==0 || p->pLimit!=0 );
  if( p->pLimit ){
    p->iLimit = iLimit = ++pParse->nMem;
    v = sqlite3GetVdbe(pParse);
    assert( v!=0 );
    if( sqlite3ExprIsInteger(p->pLimit, &n) ){
      sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
      VdbeComment((v, "LIMIT counter"));
      if( n==0 ){
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
      }else if( n>=0 && p->nSelectRow>(u64)n ){
        p->nSelectRow = n;
................................................................................
  if( pRet==0 && iCol<p->pEList->nExpr ){
    pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
  }
  return pRet;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

#ifndef SQLITE_OMIT_CTE
/*
** This routine generates VDBE code to compute the content of a WITH RECURSIVE
** query of the form:
**
**   <recursive-table> AS (<setup-query> UNION [ALL] <recursive-query>)
**                         \___________/             \_______________/
**                           p->pPrior                      p
**
**
** There is exactly one reference to the recursive-table in the FROM clause
** of recursive-query, marked with the SrcList->a[].isRecursive flag.
**
** The setup-query runs once to generate an initial set of rows that go
** into a Queue table.  Rows are extracted from the Queue table one by
** one.  Each row extracted from Queue is output to pDest.  Then the single
** extracted row (now in the iCurrent table) becomes the content of the
** recursive-table for a recursive-query run.  The output of the recursive-query
** is added back into the Queue table.  Then another row is extracted from Queue
** and the iteration continues until the Queue table is empty.
**
** If the compound query operator is UNION then no duplicate rows are ever
** inserted into the Queue table.  The iDistinct table keeps a copy of all rows
** that have ever been inserted into Queue and causes duplicates to be
** discarded.  If the operator is UNION ALL, then duplicates are allowed.
** 
** If the query has an ORDER BY, then entries in the Queue table are kept in
** ORDER BY order and the first entry is extracted for each cycle.  Without
** an ORDER BY, the Queue table is just a FIFO.
**
** If a LIMIT clause is provided, then the iteration stops after LIMIT rows
** have been output to pDest.  A LIMIT of zero means to output no rows and a
** negative LIMIT means to output all rows.  If there is also an OFFSET clause
** with a positive value, then the first OFFSET outputs are discarded rather
** than being sent to pDest.  The LIMIT count does not begin until after OFFSET
** rows have been skipped.
*/
static void generateWithRecursiveQuery(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The recursive SELECT to be coded */
  SelectDest *pDest     /* What to do with query results */
){
  SrcList *pSrc = p->pSrc;      /* The FROM clause of the recursive query */
  int nCol = p->pEList->nExpr;  /* Number of columns in the recursive table */
  Vdbe *v = pParse->pVdbe;      /* The prepared statement under construction */
  Select *pSetup = p->pPrior;   /* The setup query */
  int addrTop;                  /* Top of the loop */
  int addrCont, addrBreak;      /* CONTINUE and BREAK addresses */
  int iCurrent;                 /* The Current table */
  int regCurrent;               /* Register holding Current table */
  int iQueue;                   /* The Queue table */
  int iDistinct = 0;            /* To ensure unique results if UNION */
  int eDest = SRT_Table;        /* How to write to Queue */
  SelectDest destQueue;         /* SelectDest targetting the Queue table */
  int i;                        /* Loop counter */
  int rc;                       /* Result code */
  ExprList *pOrderBy;           /* The ORDER BY clause */
  Expr *pLimit, *pOffset;       /* Saved LIMIT and OFFSET */
  int regLimit, regOffset;      /* Registers used by LIMIT and OFFSET */

  /* Obtain authorization to do a recursive query */
  if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return;

  /* Process the LIMIT and OFFSET clauses, if they exist */
  addrBreak = sqlite3VdbeMakeLabel(v);
  computeLimitRegisters(pParse, p, addrBreak);
  pLimit = p->pLimit;
  pOffset = p->pOffset;
  regLimit = p->iLimit;
  regOffset = p->iOffset;
  p->pLimit = p->pOffset = 0;
  p->iLimit = p->iOffset = 0;

  /* Locate the cursor number of the Current table */
  for(i=0; ALWAYS(i<pSrc->nSrc); i++){
    if( pSrc->a[i].isRecursive ){
      iCurrent = pSrc->a[i].iCursor;
      break;
    }
  }

  /* Detach the ORDER BY clause from the compound SELECT */
  pOrderBy = p->pOrderBy;
  p->pOrderBy = 0;

  /* Allocate cursors numbers for Queue and Distinct.  The cursor number for
  ** the Distinct table must be exactly one greater than Queue in order
  ** for the SRT_DistTable and SRT_DistQueue destinations to work. */
  iQueue = pParse->nTab++;
  if( p->op==TK_UNION ){
    eDest = pOrderBy ? SRT_DistQueue : SRT_DistTable;
    iDistinct = pParse->nTab++;
  }else{
    eDest = pOrderBy ? SRT_Queue : SRT_Table;
  }
  sqlite3SelectDestInit(&destQueue, eDest, iQueue);

  /* Allocate cursors for Current, Queue, and Distinct. */
  regCurrent = ++pParse->nMem;
  sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol);
  if( pOrderBy ){
    KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pOrderBy, 1);
    sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0,
                      (char*)pKeyInfo, P4_KEYINFO);
    destQueue.pOrderBy = pOrderBy;
  }else{
    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol);
  }
  VdbeComment((v, "Queue table"));
  if( iDistinct ){
    p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0);
    p->selFlags |= SF_UsesEphemeral;
  }

  /* Store the results of the setup-query in Queue. */
  rc = sqlite3Select(pParse, pSetup, &destQueue);
  if( rc ) goto end_of_recursive_query;

  /* Find the next row in the Queue and output that row */
  addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak);

  /* Transfer the next row in Queue over to Current */
  sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */
  if( pOrderBy ){
    sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent);
  }else{
    sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
  }
  sqlite3VdbeAddOp1(v, OP_Delete, iQueue);

  /* Output the single row in Current */
  addrCont = sqlite3VdbeMakeLabel(v);
  codeOffset(v, regOffset, addrCont);
  selectInnerLoop(pParse, p, p->pEList, iCurrent,
      0, 0, pDest, addrCont, addrBreak);
  if( regLimit ) sqlite3VdbeAddOp3(v, OP_IfZero, regLimit, addrBreak, -1);
  sqlite3VdbeResolveLabel(v, addrCont);

  /* Execute the recursive SELECT taking the single row in Current as
  ** the value for the recursive-table. Store the results in the Queue.
  */
  p->pPrior = 0;
  sqlite3Select(pParse, p, &destQueue);
  assert( p->pPrior==0 );
  p->pPrior = pSetup;

  /* Keep running the loop until the Queue is empty */
  sqlite3VdbeAddOp2(v, OP_Goto, 0, addrTop);
  sqlite3VdbeResolveLabel(v, addrBreak);

end_of_recursive_query:
  p->pOrderBy = pOrderBy;
  p->pLimit = pLimit;
  p->pOffset = pOffset;
  return;
}
#endif

/* Forward references */
static int multiSelectOrderBy(
  Parse *pParse,        /* Parsing context */
  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
);


................................................................................
    }
    rc = 1;
    goto multi_select_end;
  }

#ifndef SQLITE_OMIT_CTE
  if( p->selFlags & SF_Recursive ){
    generateWithRecursiveQuery(pParse, p, &dest);










































































  }else
#endif

  /* Compound SELECTs that have an ORDER BY clause are handled separately.
  */
  if( p->pOrderBy ){
    return multiSelectOrderBy(pParse, p, pDest);
................................................................................
          generateColumnNames(pParse, 0, pFirst->pEList);
        }
        iBreak = sqlite3VdbeMakeLabel(v);
        iCont = sqlite3VdbeMakeLabel(v);
        computeLimitRegisters(pParse, p, iBreak);
        sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak);
        iStart = sqlite3VdbeCurrentAddr(v);
        selectInnerLoop(pParse, p, p->pEList, unionTab,
                        0, 0, &dest, iCont, iBreak);
        sqlite3VdbeResolveLabel(v, iCont);
        sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart);
        sqlite3VdbeResolveLabel(v, iBreak);
        sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
      }
      break;
................................................................................
      iCont = sqlite3VdbeMakeLabel(v);
      computeLimitRegisters(pParse, p, iBreak);
      sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak);
      r1 = sqlite3GetTempReg(pParse);
      iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1);
      sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0);
      sqlite3ReleaseTempReg(pParse, r1);
      selectInnerLoop(pParse, p, p->pEList, tab1,
                      0, 0, &dest, iCont, iBreak);
      sqlite3VdbeResolveLabel(v, iCont);
      sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart);
      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
................................................................................
    sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1);
    sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
  }
  if( pParse->db->mallocFailed ) return 0;

  /* Suppress the first OFFSET entries if there is an OFFSET clause
  */
  codeOffset(v, p->iOffset, iContinue);

  switch( pDest->eDest ){
    /* Store the result as data using a unique key.
    */
    case SRT_Table:
    case SRT_EphemTab: {
      int r1 = sqlite3GetTempReg(pParse);
................................................................................
      Expr *pE = pFunc->pExpr;
      assert( !ExprHasProperty(pE, EP_xIsSelect) );
      if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
        sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
           "argument");
        pFunc->iDistinct = -1;
      }else{
        KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList, 0);
        sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
                          (char*)pKeyInfo, P4_KEYINFO);
      }
    }
  }
}

................................................................................
#else
# define explainSimpleCount(a,b,c)
#endif

/*
** Generate code for the SELECT statement given in the p argument.  
**
** The results are returned according to the SelectDest structure.
** See comments in sqliteInt.h for further information.










































**
** This routine returns the number of errors.  If any errors are
** encountered, then an appropriate error message is left in
** pParse->zErrMsg.
**
** This routine does NOT free the Select structure passed in.  The
** calling function needs to do that.
................................................................................
  ** extracted in pre-sorted order.  If that is the case, then the
  ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
  ** we figure out that the sorting index is not needed.  The addrSortIndex
  ** variable is used to facilitate that change.
  */
  if( pOrderBy ){
    KeyInfo *pKeyInfo;
    pKeyInfo = keyInfoFromExprList(pParse, pOrderBy, 0);
    pOrderBy->iECursor = pParse->nTab++;
    p->addrOpenEphm[2] = addrSortIndex =
      sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                           pOrderBy->iECursor, pOrderBy->nExpr+2, 0,
                           (char*)pKeyInfo, P4_KEYINFO);
  }else{
    addrSortIndex = -1;
................................................................................

  /* Open a virtual index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    sDistinct.tabTnct = pParse->nTab++;
    sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
                                sDistinct.tabTnct, 0, 0,
                                (char*)keyInfoFromExprList(pParse, p->pEList, 0),
                                P4_KEYINFO);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

................................................................................
    */
    if( addrSortIndex>=0 && pOrderBy==0 ){
      sqlite3VdbeChangeToNoop(v, addrSortIndex);
      p->addrOpenEphm[2] = -1;
    }

    /* Use the standard inner loop. */
    selectInnerLoop(pParse, p, pEList, -1, pOrderBy, &sDistinct, pDest,
                    sqlite3WhereContinueLabel(pWInfo),
                    sqlite3WhereBreakLabel(pWInfo));

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);
  }else{
................................................................................

      /* If there is a GROUP BY clause we might need a sorting index to
      ** implement it.  Allocate that sorting index now.  If it turns out
      ** that we do not need it after all, the OP_SorterOpen instruction
      ** will be converted into a Noop.  
      */
      sAggInfo.sortingIdx = pParse->nTab++;
      pKeyInfo = keyInfoFromExprList(pParse, pGroupBy, 0);
      addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, 
          sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 
          0, (char*)pKeyInfo, P4_KEYINFO);

      /* Initialize memory locations used by GROUP BY aggregate processing
      */
      iUseFlag = ++pParse->nMem;
................................................................................
      sqlite3VdbeResolveLabel(v, addrOutputRow);
      addrOutputRow = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
      VdbeComment((v, "Groupby result generator entry point"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      finalizeAggFunctions(pParse, &sAggInfo);
      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, -1, pOrderBy,
                      &sDistinct, pDest,
                      addrOutputRow+1, addrSetAbort);
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      VdbeComment((v, "end groupby result generator"));

      /* Generate a subroutine that will reset the group-by accumulator
      */
................................................................................
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);
      }

      pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, -1, 0, 0, 
                      pDest, addrEnd, addrEnd);
      sqlite3ExprListDelete(db, pDel);
    }
    sqlite3VdbeResolveLabel(v, addrEnd);
    
  } /* endif aggregate query */

Changes to src/shell.c.

1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
....
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
**
**     * For each "Next", "Prev", "VNext" or "VPrev" instruction, indent
**       all opcodes that occur between the p2 jump destination and the opcode
**       itself by 2 spaces.
**
**     * For each "Goto", if the jump destination is earlier in the program
**       and ends on one of:
**          Yield  SeekGt  SeekLt  RowSetRead
**       then indent all opcodes between the earlier instruction
**       and "Goto" by 2 spaces.
*/
static void explain_data_prepare(struct callback_data *p, sqlite3_stmt *pSql){
  const char *zSql;               /* The text of the SQL statement */
  const char *z;                  /* Used to check if this is an EXPLAIN */
  int *abYield = 0;               /* True if op is an OP_Yield */
  int nAlloc = 0;                 /* Allocated size of p->aiIndent[], abYield */
  int iOp;                        /* Index of operation in p->aiIndent[] */

  const char *azNext[] = { "Next", "Prev", "VPrev", "VNext", "SorterNext", 0 };
  const char *azYield[] = { "Yield", "SeekLt", "SeekGt", "RowSetRead", 0 };
  const char *azGoto[] = { "Goto", 0 };

  /* Try to figure out if this is really an EXPLAIN statement. If this
  ** cannot be verified, return early.  */
  zSql = sqlite3_sql(pSql);
  if( zSql==0 ) return;
  for(z=zSql; *z==' ' || *z=='\t' || *z=='\n' || *z=='\f' || *z=='\r'; z++);
................................................................................
    p->aiIndent[iOp] = 0;
    p->nIndent = iOp+1;

    if( str_in_array(zOp, azNext) ){
      for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
    }
    if( str_in_array(zOp, azGoto) && p2op<p->nIndent && abYield[p2op] ){
      for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
    }
  }

  p->iIndent = 0;
  sqlite3_free(abYield);
  sqlite3_reset(pSql);
}







|











|







 







|







1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
....
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
**
**     * For each "Next", "Prev", "VNext" or "VPrev" instruction, indent
**       all opcodes that occur between the p2 jump destination and the opcode
**       itself by 2 spaces.
**
**     * For each "Goto", if the jump destination is earlier in the program
**       and ends on one of:
**          Yield  SeekGt  SeekLt  RowSetRead  Rewind
**       then indent all opcodes between the earlier instruction
**       and "Goto" by 2 spaces.
*/
static void explain_data_prepare(struct callback_data *p, sqlite3_stmt *pSql){
  const char *zSql;               /* The text of the SQL statement */
  const char *z;                  /* Used to check if this is an EXPLAIN */
  int *abYield = 0;               /* True if op is an OP_Yield */
  int nAlloc = 0;                 /* Allocated size of p->aiIndent[], abYield */
  int iOp;                        /* Index of operation in p->aiIndent[] */

  const char *azNext[] = { "Next", "Prev", "VPrev", "VNext", "SorterNext", 0 };
  const char *azYield[] = { "Yield", "SeekLt", "SeekGt", "RowSetRead", "Rewind", 0 };
  const char *azGoto[] = { "Goto", 0 };

  /* Try to figure out if this is really an EXPLAIN statement. If this
  ** cannot be verified, return early.  */
  zSql = sqlite3_sql(pSql);
  if( zSql==0 ) return;
  for(z=zSql; *z==' ' || *z=='\t' || *z=='\n' || *z=='\f' || *z=='\r'; z++);
................................................................................
    p->aiIndent[iOp] = 0;
    p->nIndent = iOp+1;

    if( str_in_array(zOp, azNext) ){
      for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
    }
    if( str_in_array(zOp, azGoto) && p2op<p->nIndent && abYield[p2op] ){
      for(i=p2op+1; i<iOp; i++) p->aiIndent[i] += 2;
    }
  }

  p->iIndent = 0;
  sqlite3_free(abYield);
  sqlite3_reset(pSql);
}

Changes to src/sqliteInt.h.

2163
2164
2165
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2171


























































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2179
2180
2181
2182
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2187


2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198

2199
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2201
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2204
2205
#define SF_Materialize     0x0100  /* Force materialization of views */
#define SF_NestedFrom      0x0200  /* Part of a parenthesized FROM clause */
#define SF_MaybeConvert    0x0400  /* Need convertCompoundSelectToSubquery() */
#define SF_Recursive       0x0800  /* The recursive part of a recursive CTE */


/*
** The results of a select can be distributed in several ways.  The
** "SRT" prefix means "SELECT Result Type".


























































*/
#define SRT_Union        1  /* Store result as keys in an index */
#define SRT_Except       2  /* Remove result from a UNION index */
#define SRT_Exists       3  /* Store 1 if the result is not empty */
#define SRT_Discard      4  /* Do not save the results anywhere */

/* The ORDER BY clause is ignored for all of the above */
#define IgnorableOrderby(X) ((X->eDest)<=SRT_Discard)

#define SRT_Output       5  /* Output each row of result */
#define SRT_Mem          6  /* Store result in a memory cell */
#define SRT_Set          7  /* Store results as keys in an index */
#define SRT_Table        8  /* Store result as data with an automatic rowid */
#define SRT_EphemTab     9  /* Create transient tab and store like SRT_Table */
#define SRT_Coroutine   10  /* Generate a single row of result */

#define SRT_DistTable   11  /* Like SRT_TABLE, but unique results only */



/*
** An instance of this object describes where to put of the results of
** a SELECT statement.
*/
struct SelectDest {
  u8 eDest;         /* How to dispose of the results.  On of SRT_* above. */
  char affSdst;     /* Affinity used when eDest==SRT_Set */
  int iSDParm;      /* A parameter used by the eDest disposal method */
  int iSdst;        /* Base register where results are written */
  int nSdst;        /* Number of registers allocated */

};

/*
** During code generation of statements that do inserts into AUTOINCREMENT 
** tables, the following information is attached to the Table.u.autoInc.p
** pointer of each autoincrement table to record some side information that
** the code generator needs.  We have to keep per-table autoincrement







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>







2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
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2195
2196
2197
2198
2199
2200
2201
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2209
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2222
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2234
2235
2236
2237
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2239
2240
2241

2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
#define SF_Materialize     0x0100  /* Force materialization of views */
#define SF_NestedFrom      0x0200  /* Part of a parenthesized FROM clause */
#define SF_MaybeConvert    0x0400  /* Need convertCompoundSelectToSubquery() */
#define SF_Recursive       0x0800  /* The recursive part of a recursive CTE */


/*
** The results of a SELECT can be distributed in several ways, as defined
** by one of the following macros.  The "SRT" prefix means "SELECT Result
** Type".
**
**     SRT_Union       Store results as a key in a temporary index 
**                     identified by pDest->iSDParm.
**
**     SRT_Except      Remove results from the temporary index pDest->iSDParm.
**
**     SRT_Exists      Store a 1 in memory cell pDest->iSDParm if the result
**                     set is not empty.
**
**     SRT_Discard     Throw the results away.  This is used by SELECT
**                     statements within triggers whose only purpose is
**                     the side-effects of functions.
**
** All of the above are free to ignore their ORDER BY clause. Those that
** follow must honor the ORDER BY clause.
**
**     SRT_Output      Generate a row of output (using the OP_ResultRow
**                     opcode) for each row in the result set.
**
**     SRT_Mem         Only valid if the result is a single column.
**                     Store the first column of the first result row
**                     in register pDest->iSDParm then abandon the rest
**                     of the query.  This destination implies "LIMIT 1".
**
**     SRT_Set         The result must be a single column.  Store each
**                     row of result as the key in table pDest->iSDParm. 
**                     Apply the affinity pDest->affSdst before storing
**                     results.  Used to implement "IN (SELECT ...)".
**
**     SRT_EphemTab    Create an temporary table pDest->iSDParm and store
**                     the result there. The cursor is left open after
**                     returning.  This is like SRT_Table except that
**                     this destination uses OP_OpenEphemeral to create
**                     the table first.
**
**     SRT_Coroutine   Generate a co-routine that returns a new row of
**                     results each time it is invoked.  The entry point
**                     of the co-routine is stored in register pDest->iSDParm
**                     and the result row is stored in pDest->nDest registers
**                     starting with pDest->iSdst.
**
**     SRT_Table       Store results in temporary table pDest->iSDParm.
**                     This is like SRT_EphemTab except that the table
**                     is assumed to already be open.
**
**     SRT_DistTable   Store results in a temporary table pDest->iSDParm.
**                     But also use temporary table pDest->iSDParm+1 as
**                     a record of all prior results and ignore any duplicate
**                     rows.  Name means:  "Distinct Table".
**
**     SRT_Queue       Store results in priority queue pDest->iSDParm (really
**                     an index).  Append a sequence number so that all entries
**                     are distinct.
**
**     SRT_DistQueue   Store results in priority queue pDest->iSDParm only if
**                     the same record has never been stored before.  The
**                     index at pDest->iSDParm+1 hold all prior stores.
*/
#define SRT_Union        1  /* Store result as keys in an index */
#define SRT_Except       2  /* Remove result from a UNION index */
#define SRT_Exists       3  /* Store 1 if the result is not empty */
#define SRT_Discard      4  /* Do not save the results anywhere */

/* The ORDER BY clause is ignored for all of the above */
#define IgnorableOrderby(X) ((X->eDest)<=SRT_Discard)

#define SRT_Output       5  /* Output each row of result */
#define SRT_Mem          6  /* Store result in a memory cell */
#define SRT_Set          7  /* Store results as keys in an index */

#define SRT_EphemTab     8  /* Create transient tab and store like SRT_Table */
#define SRT_Coroutine    9  /* Generate a single row of result */
#define SRT_Table       10  /* Store result as data with an automatic rowid */
#define SRT_DistTable   11  /* Like SRT_Table, but unique results only */
#define SRT_Queue       12  /* Store result in an queue */
#define SRT_DistQueue   13  /* Like SRT_Queue, but unique results only */

/*
** An instance of this object describes where to put of the results of
** a SELECT statement.
*/
struct SelectDest {
  u8 eDest;            /* How to dispose of the results.  On of SRT_* above. */
  char affSdst;        /* Affinity used when eDest==SRT_Set */
  int iSDParm;         /* A parameter used by the eDest disposal method */
  int iSdst;           /* Base register where results are written */
  int nSdst;           /* Number of registers allocated */
  ExprList *pOrderBy;  /* Key columns for SRT_Queue and SRT_DistQueue */
};

/*
** During code generation of statements that do inserts into AUTOINCREMENT 
** tables, the following information is attached to the Table.u.autoInc.p
** pointer of each autoincrement table to record some side information that
** the code generator needs.  We have to keep per-table autoincrement

Changes to src/vdbe.c.

3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
....
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
      pCx->isTable = 1;
    }
  }
  pCx->isOrdered = (pOp->p5!=BTREE_UNORDERED);
  break;
}

#ifndef SQLITE_OMIT_CTE
/* Opcode: SwapCursors P1 P2 * * *
**
** Parameters P1 and P2 are both cursors opened by the OpenEphemeral
** opcode. This opcode deletes the contents of epheremal table P1,
** then renames P2 to P1 and P1 to P2. In other words, following this
** opcode cursor P2 is open on an empty table and P1 is open on the
** table that was initially accessed by P2.
*/
case OP_SwapCursors: {
  Mem tmp;
  VdbeCursor *pTmp;

  tmp = p->aMem[p->nMem - pOp->p1];
  p->aMem[p->nMem - pOp->p1] = p->aMem[p->nMem - pOp->p2];
  p->aMem[p->nMem - pOp->p2] = tmp;

  pTmp = p->apCsr[pOp->p1];
  p->apCsr[pOp->p1] = p->apCsr[pOp->p2];
  p->apCsr[pOp->p2] = pTmp;

  assert( pTmp->isTable );
  rc = sqlite3BtreeClearTable(pTmp->pBt, MASTER_ROOT, 0);
  break;
}
#endif /* ifndef SQLITE_OMIT_CTE */

/* Opcode: SorterOpen P1 * * P4 *
**
** This opcode works like OP_OpenEphemeral except that it opens
** a transient index that is specifically designed to sort large
** tables using an external merge-sort algorithm.
*/
case OP_SorterOpen: {
................................................................................

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pC->nullRow = 1;
  pC->rowidIsValid = 0;
  pC->cacheStatus = CACHE_STALE;
  assert( pC->pCursor || pC->pVtabCursor );
  if( pC->pCursor ){
    sqlite3BtreeClearCursor(pC->pCursor);
  }
  break;
}

/* Opcode: Last P1 P2 * * *







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<







 







<







3365
3366
3367
3368
3369
3370
3371



























3372
3373
3374
3375
3376
3377
3378
....
4362
4363
4364
4365
4366
4367
4368

4369
4370
4371
4372
4373
4374
4375
      pCx->isTable = 1;
    }
  }
  pCx->isOrdered = (pOp->p5!=BTREE_UNORDERED);
  break;
}




























/* Opcode: SorterOpen P1 * * P4 *
**
** This opcode works like OP_OpenEphemeral except that it opens
** a transient index that is specifically designed to sort large
** tables using an external merge-sort algorithm.
*/
case OP_SorterOpen: {
................................................................................

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pC->nullRow = 1;
  pC->rowidIsValid = 0;
  pC->cacheStatus = CACHE_STALE;

  if( pC->pCursor ){
    sqlite3BtreeClearCursor(pC->pCursor);
  }
  break;
}

/* Opcode: Last P1 P2 * * *

Changes to src/where.c.

3406
3407
3408
3409
3410
3411
3412





3413
3414
3415
3416
3417

3418
3419
3420
3421
3422
3423
3424
  {
    /* Case 6:  There is no usable index.  We must do a complete
    **          scan of the entire table.
    */
    static const u8 aStep[] = { OP_Next, OP_Prev };
    static const u8 aStart[] = { OP_Rewind, OP_Last };
    assert( bRev==0 || bRev==1 );





    pLevel->op = aStep[bRev];
    pLevel->p1 = iCur;
    pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
    pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
  }


  /* Insert code to test every subexpression that can be completely
  ** computed using the current set of tables.
  */
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE;
    testcase( pTerm->wtFlags & TERM_VIRTUAL );







>
>
>
>
>





>







3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
  {
    /* Case 6:  There is no usable index.  We must do a complete
    **          scan of the entire table.
    */
    static const u8 aStep[] = { OP_Next, OP_Prev };
    static const u8 aStart[] = { OP_Rewind, OP_Last };
    assert( bRev==0 || bRev==1 );
    if( pTabItem->isRecursive ){
      /* Tables marked isRecursive have only a single row that is stored in
      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
      pLevel->op = OP_Noop;
    }else{
      pLevel->op = aStep[bRev];
      pLevel->p1 = iCur;
      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }
  }

  /* Insert code to test every subexpression that can be completely
  ** computed using the current set of tables.
  */
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE;
    testcase( pTerm->wtFlags & TERM_VIRTUAL );

Changes to test/with1.test.

148
149
150
151
152
153
154























155
156

























157
158
159
160

161
162
163
164
165
166
167
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i)
  SELECT x FROM i LIMIT 10;
} {1 2 3 4 5 6 7 8 9 10}

do_catchsql_test 5.2 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i ORDER BY 1)
  SELECT x FROM i LIMIT 10;























} {1 {ORDER BY in a recursive query}}


























do_catchsql_test 5.3 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i LIMIT 10 )
  SELECT x FROM i LIMIT 10;
} {1 {LIMIT in a recursive query}}


do_execsql_test 5.4 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT (x+1)%10 FROM i)
  SELECT x FROM i LIMIT 20;
} {1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0}

do_execsql_test 5.5 {







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148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207

208
209
210
211
212
213
214
215
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i)
  SELECT x FROM i LIMIT 10;
} {1 2 3 4 5 6 7 8 9 10}

do_catchsql_test 5.2 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i ORDER BY 1)
  SELECT x FROM i LIMIT 10;
} {0 {1 2 3 4 5 6 7 8 9 10}}

do_execsql_test 5.2.1 {
  CREATE TABLE edge(xfrom, xto, seq, PRIMARY KEY(xfrom, xto)) WITHOUT ROWID;
  INSERT INTO edge VALUES(0, 1, 10);
  INSERT INTO edge VALUES(1, 2, 20);
  INSERT INTO edge VALUES(0, 3, 30);
  INSERT INTO edge VALUES(2, 4, 40);
  INSERT INTO edge VALUES(3, 4, 40);
  INSERT INTO edge VALUES(2, 5, 50);
  INSERT INTO edge VALUES(3, 6, 60);
  INSERT INTO edge VALUES(5, 7, 70);
  INSERT INTO edge VALUES(3, 7, 70);
  INSERT INTO edge VALUES(4, 8, 80);
  INSERT INTO edge VALUES(7, 8, 80);
  INSERT INTO edge VALUES(8, 9, 90);
  
  WITH RECURSIVE
    ancest(id, mtime) AS
      (VALUES(0, 0)
       UNION
       SELECT edge.xto, edge.seq FROM edge, ancest
        WHERE edge.xfrom=ancest.id
        ORDER BY 2
      )
  SELECT * FROM ancest;
} {0 0 1 10 2 20 3 30 4 40 5 50 6 60 7 70 8 80 9 90}
do_execsql_test 5.2.2 {
  WITH RECURSIVE
    ancest(id, mtime) AS
      (VALUES(0, 0)
       UNION ALL
       SELECT edge.xto, edge.seq FROM edge, ancest
        WHERE edge.xfrom=ancest.id
        ORDER BY 2
      )
  SELECT * FROM ancest;
} {0 0 1 10 2 20 3 30 4 40 4 40 5 50 6 60 7 70 7 70 8 80 8 80 8 80 8 80 9 90 9 90 9 90 9 90}
do_execsql_test 5.2.3 {
  WITH RECURSIVE
    ancest(id, mtime) AS
      (VALUES(0, 0)
       UNION ALL
       SELECT edge.xto, edge.seq FROM edge, ancest
        WHERE edge.xfrom=ancest.id
        ORDER BY 2 LIMIT 4 OFFSET 2
      )
  SELECT * FROM ancest;
} {2 20 3 30 4 40 4 40}

do_catchsql_test 5.3 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i LIMIT 5)
  SELECT x FROM i;

} {0 {1 2 3 4 5}}

do_execsql_test 5.4 {
  WITH i(x) AS ( VALUES(1) UNION ALL SELECT (x+1)%10 FROM i)
  SELECT x FROM i LIMIT 20;
} {1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0}

do_execsql_test 5.5 {