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Overview
Comment:Change the names of SRT_DistTable and SRT_Table used by CTE to more meaningful SRT_DistFifo and SRT_Fifo, respectively. Simplify the IgnorableOrderby() macro in the process.
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SHA1:45d8cc678d128f1dda6469864215a8ed9de4366a
User & Date: drh 2014-03-21 19:56:09
Context
2014-03-21
20:58
Add the ability to use indices for the first few terms of an ORDER BY clause, then sort in batches to handle the later terms. check-in: fa06a6fe user: drh tags: trunk
19:56
Change the names of SRT_DistTable and SRT_Table used by CTE to more meaningful SRT_DistFifo and SRT_Fifo, respectively. Simplify the IgnorableOrderby() macro in the process. check-in: 45d8cc67 user: drh tags: trunk
19:27
Avoid leaking memory in an obscure case where the flattener adds an ORDER BY clause to the recursive part of a recursive query. check-in: 1f413aca user: dan tags: trunk
Changes
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Changes to src/select.c.

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      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.  */
        int addr = sqlite3VdbeCurrentAddr(v) + 4;
        sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0); VdbeCoverage(v);
        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1);
................................................................................
  Select *pSetup = p->pPrior;   /* The setup query */
  int addrTop;                  /* Top of the loop */
  int addrCont, addrBreak;      /* CONTINUE and BREAK addresses */
  int iCurrent = 0;             /* 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 */

................................................................................
      iCurrent = pSrc->a[i].iCursor;
      break;
    }
  }

  /* 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 ){
................................................................................
  db = pParse->db;
  if( p==0 || db->mallocFailed || pParse->nErr ){
    return 1;
  }
  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
  memset(&sAggInfo, 0, sizeof(sAggInfo));

  assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistTable );

  assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue );
  assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue );
  if( IgnorableOrderby(pDest) ){
    assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || 
           pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard ||
           pDest->eDest==SRT_Queue  || pDest->eDest==SRT_DistTable ||
           pDest->eDest==SRT_DistQueue);
    /* If ORDER BY makes no difference in the output then neither does
    ** DISTINCT so it can be removed too. */
    sqlite3ExprListDelete(db, p->pOrderBy);
    p->pOrderBy = 0;
    p->selFlags &= ~SF_Distinct;
  }
  sqlite3SelectPrep(pParse, p, 0);







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      sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol);
      break;
    }
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

    /* Store the result as data using a unique key.
    */
    case SRT_Fifo:
    case SRT_DistFifo:
    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_DistFifo ){
        /* If the destination is DistFifo, 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.  */
        int addr = sqlite3VdbeCurrentAddr(v) + 4;
        sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0); VdbeCoverage(v);
        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1);
................................................................................
  Select *pSetup = p->pPrior;   /* The setup query */
  int addrTop;                  /* Top of the loop */
  int addrCont, addrBreak;      /* CONTINUE and BREAK addresses */
  int iCurrent = 0;             /* 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_Fifo;         /* 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 */

................................................................................
      iCurrent = pSrc->a[i].iCursor;
      break;
    }
  }

  /* 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_DistFifo and SRT_DistQueue destinations to work. */
  iQueue = pParse->nTab++;
  if( p->op==TK_UNION ){
    eDest = pOrderBy ? SRT_DistQueue : SRT_DistFifo;
    iDistinct = pParse->nTab++;
  }else{
    eDest = pOrderBy ? SRT_Queue : SRT_Fifo;
  }
  sqlite3SelectDestInit(&destQueue, eDest, iQueue);

  /* Allocate cursors for Current, Queue, and Distinct. */
  regCurrent = ++pParse->nMem;
  sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol);
  if( pOrderBy ){
................................................................................
  db = pParse->db;
  if( p==0 || db->mallocFailed || pParse->nErr ){
    return 1;
  }
  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
  memset(&sAggInfo, 0, sizeof(sAggInfo));

  assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistFifo );
  assert( p->pOrderBy==0 || pDest->eDest!=SRT_Fifo );
  assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue );
  assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue );
  if( IgnorableOrderby(pDest) ){
    assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || 
           pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard ||
           pDest->eDest==SRT_Queue  || pDest->eDest==SRT_DistFifo ||
           pDest->eDest==SRT_DistQueue || pDest->eDest==SRT_Fifo);
    /* If ORDER BY makes no difference in the output then neither does
    ** DISTINCT so it can be removed too. */
    sqlite3ExprListDelete(db, p->pOrderBy);
    p->pOrderBy = 0;
    p->selFlags &= ~SF_Distinct;
  }
  sqlite3SelectPrep(pParse, p, 0);

Changes to src/sqliteInt.h.

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**     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 || (X->eDest)>SRT_Table)

#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. */







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**     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.
**     SRT_Fifo        This is like SRT_EphemTab except that the table
**                     is assumed to already be open.  SRT_Fifo has
**                     the additional property of being able to ignore
**                     the ORDER BY clause.
**
**     SRT_DistFifo    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 Fifo".
**
**     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 */
#define SRT_Fifo         5  /* Store result as data with an automatic rowid */
#define SRT_DistFifo     6  /* Like SRT_Fifo, but unique results only */
#define SRT_Queue        7  /* Store result in an queue */
#define SRT_DistQueue    8  /* Like SRT_Queue, but unique results only */

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

#define SRT_Output       9  /* Output each row of result */
#define SRT_Mem         10  /* Store result in a memory cell */
#define SRT_Set         11  /* Store results as keys in an index */
#define SRT_EphemTab    12  /* Create transient tab and store like SRT_Table */
#define SRT_Coroutine   13  /* Generate a single row of result */
#define SRT_Table       14  /* Store result as data with an automatic rowid */




/*
** 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. */