SQLite

            if( aiMap ) aiMap[i] = j;
          }
  
          assert( i==nExpr || colUsed!=(MASKBIT(nExpr)-1) );
          if( colUsed==(MASKBIT(nExpr)-1) ){
            /* If we reach this point, that means the index pIdx is usable */
            int iAddr = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
#ifndef SQLITE_OMIT_EXPLAIN
            sqlite3VdbeAddOp4(v, OP_Explain, 0, 0, 0,
              sqlite3MPrintf(db, "USING INDEX %s FOR IN-OPERATOR",pIdx->zName),
              P4_DYNAMIC);
#endif
            sqlite3VdbeAddOp3(v, OP_OpenRead, iTab, pIdx->tnum, iDb);
            sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
            VdbeComment((v, "%s", pIdx->zName));
            assert( IN_INDEX_INDEX_DESC == IN_INDEX_INDEX_ASC+1 );
            eType = IN_INDEX_INDEX_ASC + pIdx->aSortOrder[0];
  
            if( prRhsHasNull ){

        **
        ** Generate code to write the results of the select into the temporary
        ** table allocated and opened above.
        */
        Select *pSelect = pExpr->x.pSelect;
        ExprList *pEList = pSelect->pEList;

#ifndef SQLITE_OMIT_EXPLAIN
        if( pParse->explain==2 ){
          char *zMsg = sqlite3MPrintf(pParse->db, "EXECUTE %sLIST SUBQUERY %d",
            jmpIfDynamic>=0?"":"CORRELATED ",
            pParse->iNextSelectId
          );
          sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg,
                            P4_DYNAMIC);
        }
#endif

        assert( !isRowid );
        /* If the LHS and RHS of the IN operator do not match, that
        ** error will have been caught long before we reach this point. */
        if( ALWAYS(pEList->nExpr==nVal) ){
          SelectDest dest;
          int i;
          sqlite3SelectDestInit(&dest, SRT_Set, pExpr->iTable);

      Expr *pLimit;                         /* New limit expression */

      testcase( pExpr->op==TK_EXISTS );
      testcase( pExpr->op==TK_SELECT );
      assert( pExpr->op==TK_EXISTS || pExpr->op==TK_SELECT );
      assert( ExprHasProperty(pExpr, EP_xIsSelect) );

#ifndef SQLITE_OMIT_EXPLAIN
      if( pParse->explain==2 ){
        char *zMsg = sqlite3MPrintf(pParse->db, "EXECUTE %sSCALAR SUBQUERY %d",
            jmpIfDynamic>=0?"":"CORRELATED ",
            pParse->iNextSelectId
        );
        sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg,
                          P4_DYNAMIC);
      }
#endif

      pSel = pExpr->x.pSelect;
      nReg = pExpr->op==TK_SELECT ? pSel->pEList->nExpr : 1;
      sqlite3SelectDestInit(&dest, 0, pParse->nMem+1);
      pParse->nMem += nReg;
      if( pExpr->op==TK_SELECT ){
        dest.eDest = SRT_Mem;
        dest.iSdst = dest.iSDParm;
        dest.nSdst = nReg;

/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X)  \
  if(sqlite3SelectTrace&(K))   \
    sqlite3DebugPrintf("%s/%d/%p: ",(S)->zSelName,(P)->iSelectId,(S)),\
    sqlite3DebugPrintf X
#else
# define SELECTTRACE(K,P,S,X)
#endif


/*

  pNew->pEList = pEList;
  pNew->op = TK_SELECT;
  pNew->selFlags = selFlags;
  pNew->iLimit = 0;
  pNew->iOffset = 0;
#if SELECTTRACE_ENABLED
  pNew->zSelName[0] = 0;



#endif
  pNew->addrOpenEphm[0] = -1;
  pNew->addrOpenEphm[1] = -1;
  pNew->nSelectRow = 0;
  if( pSrc==0 ) pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*pSrc));
  pNew->pSrc = pSrc;
  pNew->pWhere = pWhere;

**
**   "USE TEMP B-TREE FOR xxx"
**
** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which
** is determined by the zUsage argument.
*/
static void explainTempTable(Parse *pParse, const char *zUsage){
  if( pParse->explain==2 ){
    Vdbe *v = pParse->pVdbe;
    char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage);
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
}

/*
** Assign expression b to lvalue a. A second, no-op, version of this macro
** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
** in sqlite3Select() to assign values to structure member variables that
** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the

#if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT)
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of one of the two forms:
**
**   "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)"
**   "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)"
**
** where iSub1 and iSub2 are the integers passed as the corresponding
** function parameters, and op is the text representation of the parameter
** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT,
** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is 
** false, or the second form if it is true.
*/
static void explainComposite(
  Parse *pParse,                  /* Parse context */
  int op,                         /* One of TK_UNION, TK_EXCEPT etc. */
  int iSub1,                      /* Subquery id 1 */
  int iSub2,                      /* Subquery id 2 */
  int bUseTmp                     /* True if a temp table was used */
){
  assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL );
  if( pParse->explain==2 ){
    Vdbe *v = pParse->pVdbe;
    char *zMsg = sqlite3MPrintf(
        pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2,
        bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op)
    );
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
}
#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainComposite(v,w,x,y,z)
#endif

/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter.  After the loop is terminated
** we need to run the sorter and output the results.  The following
** routine generates the code needed to do that.

){
  int rc = SQLITE_OK;   /* Success code from a subroutine */
  Select *pPrior;       /* Another SELECT immediately to our left */
  Vdbe *v;              /* Generate code to this VDBE */
  SelectDest dest;      /* Alternative data destination */
  Select *pDelete = 0;  /* Chain of simple selects to delete */
  sqlite3 *db;          /* Database connection */
#ifndef SQLITE_OMIT_EXPLAIN
  int iSub1 = 0;        /* EQP id of left-hand query */
  int iSub2 = 0;        /* EQP id of right-hand query */
#endif

  /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs.  Only
  ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
  */
  assert( p && p->pPrior );  /* Calling function guarantees this much */
  assert( (p->selFlags & SF_Recursive)==0 || p->op==TK_ALL || p->op==TK_UNION );
  db = pParse->db;

  */
  if( p->pOrderBy ){
    return multiSelectOrderBy(pParse, p, pDest);
  }else

  /* Generate code for the left and right SELECT statements.
  */

  switch( p->op ){
    case TK_ALL: {
      int addr = 0;
      int nLimit;
      assert( !pPrior->pLimit );
      pPrior->iLimit = p->iLimit;
      pPrior->iOffset = p->iOffset;
      pPrior->pLimit = p->pLimit;
      explainSetInteger(iSub1, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, pPrior, &dest);
      p->pLimit = 0;
      if( rc ){
        goto multi_select_end;
      }
      p->pPrior = 0;
      p->iLimit = pPrior->iLimit;
      p->iOffset = pPrior->iOffset;
      if( p->iLimit ){
        addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
        VdbeComment((v, "Jump ahead if LIMIT reached"));
        if( p->iOffset ){
          sqlite3VdbeAddOp3(v, OP_OffsetLimit,
                            p->iLimit, p->iOffset+1, p->iOffset);
        }
      }
      explainSetInteger(iSub2, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, p, &dest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;
      p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
      if( pPrior->pLimit
       && sqlite3ExprIsInteger(pPrior->pLimit->pLeft, &nLimit)

        assert( p->pEList );
      }

      /* Code the SELECT statements to our left
      */
      assert( !pPrior->pOrderBy );
      sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
      explainSetInteger(iSub1, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, pPrior, &uniondest);
      if( rc ){
        goto multi_select_end;
      }

      /* Code the current SELECT statement
      */
      if( p->op==TK_EXCEPT ){
        op = SRT_Except;
      }else{
        assert( p->op==TK_UNION );
        op = SRT_Union;
      }
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      uniondest.eDest = op;
      explainSetInteger(iSub2, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, p, &uniondest);
      testcase( rc!=SQLITE_OK );
      /* Query flattening in sqlite3Select() might refill p->pOrderBy.
      ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
      sqlite3ExprListDelete(db, p->pOrderBy);
      pDelete = p->pPrior;
      p->pPrior = pPrior;

      p->addrOpenEphm[0] = addr;
      findRightmost(p)->selFlags |= SF_UsesEphemeral;
      assert( p->pEList );

      /* Code the SELECTs to our left into temporary table "tab1".
      */
      sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
      explainSetInteger(iSub1, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, pPrior, &intersectdest);
      if( rc ){
        goto multi_select_end;
      }

      /* Code the current SELECT into temporary table "tab2"
      */
      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
      assert( p->addrOpenEphm[1] == -1 );
      p->addrOpenEphm[1] = addr;
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      intersectdest.iSDParm = tab2;
      explainSetInteger(iSub2, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, p, &intersectdest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;
      if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
      sqlite3ExprDelete(db, p->pLimit);
      p->pLimit = pLimit;

      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
    }
  }

  explainComposite(pParse, p->op, iSub1, iSub2, p->op!=TK_ALL);

  /* Compute collating sequences used by 
  ** temporary tables needed to implement the compound select.
  ** Attach the KeyInfo structure to all temporary tables.
  **
  ** This section is run by the right-most SELECT statement only.
  ** SELECT statements to the left always skip this part.  The right-most

  int op;               /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
  KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
  KeyInfo *pKeyMerge;   /* Comparison information for merging rows */
  sqlite3 *db;          /* Database connection */
  ExprList *pOrderBy;   /* The ORDER BY clause */
  int nOrderBy;         /* Number of terms in the ORDER BY clause */
  int *aPermute;        /* Mapping from ORDER BY terms to result set columns */
#ifndef SQLITE_OMIT_EXPLAIN
  int iSub1;            /* EQP id of left-hand query */
  int iSub2;            /* EQP id of right-hand query */
#endif

  assert( p->pOrderBy!=0 );
  assert( pKeyDup==0 ); /* "Managed" code needs this.  Ticket #3382. */
  db = pParse->db;
  v = pParse->pVdbe;
  assert( v!=0 );       /* Already thrown the error if VDBE alloc failed */
  labelEnd = sqlite3VdbeMakeLabel(v);

  regAddrA = ++pParse->nMem;
  regAddrB = ++pParse->nMem;
  regOutA = ++pParse->nMem;
  regOutB = ++pParse->nMem;
  sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
  sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);



  /* Generate a coroutine to evaluate the SELECT statement to the
  ** left of the compound operator - the "A" select.
  */
  addrSelectA = sqlite3VdbeCurrentAddr(v) + 1;
  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA);
  VdbeComment((v, "left SELECT"));
  pPrior->iLimit = regLimitA;
  explainSetInteger(iSub1, pParse->iNextSelectId);
  sqlite3Select(pParse, pPrior, &destA);
  sqlite3VdbeEndCoroutine(v, regAddrA);
  sqlite3VdbeJumpHere(v, addr1);

  /* Generate a coroutine to evaluate the SELECT statement on 
  ** the right - the "B" select
  */
  addrSelectB = sqlite3VdbeCurrentAddr(v) + 1;
  addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB);
  VdbeComment((v, "right SELECT"));
  savedLimit = p->iLimit;
  savedOffset = p->iOffset;
  p->iLimit = regLimitB;
  p->iOffset = 0;  
  explainSetInteger(iSub2, pParse->iNextSelectId);
  sqlite3Select(pParse, p, &destB);
  p->iLimit = savedLimit;
  p->iOffset = savedOffset;
  sqlite3VdbeEndCoroutine(v, regAddrB);

  /* Generate a subroutine that outputs the current row of the A
  ** select as the next output row of the compound select.

    sqlite3SelectDelete(db, p->pPrior);
  }
  p->pPrior = pPrior;
  pPrior->pNext = p;

  /*** TBD:  Insert subroutine calls to close cursors on incomplete
  **** subqueries ****/
  explainComposite(pParse, p->op, iSub1, iSub2, 0);
  return pParse->nErr!=0;
}
#endif

#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)

/* An instance of the SubstContext object describes an substitution edit

static void explainSimpleCount(
  Parse *pParse,                  /* Parse context */
  Table *pTab,                    /* Table being queried */
  Index *pIdx                     /* Index used to optimize scan, or NULL */
){
  if( pParse->explain==2 ){
    int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx)));
    char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s%s%s",
        pTab->zName,
        bCover ? " USING COVERING INDEX " : "",
        bCover ? pIdx->zName : ""
    );
    sqlite3VdbeAddOp4(
        pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC
    );
  }
}
#else
# define explainSimpleCount(a,b,c)
#endif

/*

  SortCtx sSort;         /* Info on how to code the ORDER BY clause */
  AggInfo sAggInfo;      /* Information used by aggregate queries */
  int iEnd;              /* Address of the end of the query */
  sqlite3 *db;           /* The database connection */
  ExprList *pMinMaxOrderBy = 0;  /* Added ORDER BY for min/max queries */
  u8 minMaxFlag;                 /* Flag for min/max queries */

#ifndef SQLITE_OMIT_EXPLAIN
  int iRestoreSelectId = pParse->iSelectId;
  pParse->iSelectId = pParse->iNextSelectId++;
#endif

  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));
#if SELECTTRACE_ENABLED
#ifndef SQLITE_OMIT_EXPLAIN


  p->iSelectId = pParse->iSelectId;

#endif

  SELECTTRACE(1,pParse,p, ("begin processing:\n", pParse->iSelectId));
  if( sqlite3SelectTrace & 0x100 ){
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

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

#if SELECTTRACE_ENABLED
  if( sqlite3SelectTrace & 0x104 ){
    SELECTTRACE(0x104,pParse,p, ("after name resolution:\n"));
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif

  /* Get a pointer the VDBE under construction, allocating a new VDBE if one
  ** does not already exist */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto select_end;
  if( pDest->eDest==SRT_Output ){
    generateColumnNames(pParse, p);
  }

  /* Try to various optimizations (flattening subqueries, and strength
  ** reduction of join operators) in the FROM clause up into the main query
  */

  /* Handle compound SELECT statements using the separate multiSelect()
  ** procedure.
  */
  if( p->pPrior ){
    rc = multiSelect(pParse, p, pDest);
#if SELECTTRACE_ENABLED
    SELECTTRACE(0x1,pParse,p,("end compound-select processing\n"));
    if( pParse->iSelectId==0 && (sqlite3SelectTrace & 0x2000)!=0 ){
      sqlite3TreeViewSelect(0, p, 0);
    }
#endif
    explainSetInteger(pParse->iSelectId, iRestoreSelectId);
    return rc;
  }
#endif

  /* For each term in the FROM clause, do two things:
  ** (1) Authorized unreferenced tables
  ** (2) Generate code for all sub-queries

      int addrTop = sqlite3VdbeCurrentAddr(v)+1;
     
      pItem->regReturn = ++pParse->nMem;
      sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
      VdbeComment((v, "%s", pItem->pTab->zName));
      pItem->addrFillSub = addrTop;
      sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);

      explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
      sqlite3Select(pParse, pSub, &dest);
      pItem->pTab->nRowLogEst = pSub->nSelectRow;
      pItem->fg.viaCoroutine = 1;
      pItem->regResult = dest.iSdst;
      sqlite3VdbeEndCoroutine(v, pItem->regReturn);
      sqlite3VdbeJumpHere(v, addrTop-1);
      sqlite3ClearTempRegCache(pParse);

        VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));
      }else{
        VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
      }
      pPrior = isSelfJoinView(pTabList, pItem);
      if( pPrior ){
        sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
        explainSetInteger(pItem->iSelectId, pPrior->iSelectId);
        assert( pPrior->pSelect!=0 );
        pSub->nSelectRow = pPrior->pSelect->nSelectRow;
      }else{
        sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);

        explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
        sqlite3Select(pParse, pSub, &dest);
      }
      pItem->pTab->nRowLogEst = pSub->nSelectRow;
      if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
      retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
      VdbeComment((v, "end %s", pItem->pTab->zName));
      sqlite3VdbeChangeP1(v, topAddr, retAddr);

  */
select_end:
  sqlite3ExprListDelete(db, pMinMaxOrderBy);
  sqlite3DbFree(db, sAggInfo.aCol);
  sqlite3DbFree(db, sAggInfo.aFunc);
#if SELECTTRACE_ENABLED
  SELECTTRACE(0x1,pParse,p,("end processing\n"));
  if( pParse->iSelectId==0 && (sqlite3SelectTrace & 0x2000)!=0 ){
    sqlite3TreeViewSelect(0, p, 0);
  }
#endif
  explainSetInteger(pParse->iSelectId, iRestoreSelectId);
  return rc;
}

  sqlite3expert *pExpert;
  int bVerbose;
};

/* A single line in the EQP output */
typedef struct EQPGraphRow EQPGraphRow;
struct EQPGraphRow {
  int iSelectId;        /* The SelectID for this row */

  EQPGraphRow *pNext;   /* Next row in sequence */
  char zText[1];        /* Text to display for this row */
};

/* All EQP output is collected into an instance of the following */
typedef struct EQPGraph EQPGraph;
struct EQPGraph {

** instance of the following structure.
*/
typedef struct ShellState ShellState;
struct ShellState {
  sqlite3 *db;           /* The database */
  u8 autoExplain;        /* Automatically turn on .explain mode */
  u8 autoEQP;            /* Run EXPLAIN QUERY PLAN prior to seach SQL stmt */

  u8 statsOn;            /* True to display memory stats before each finalize */
  u8 scanstatsOn;        /* True to display scan stats before each finalize */
  u8 openMode;           /* SHELL_OPEN_NORMAL, _APPENDVFS, or _ZIPFILE */
  u8 doXdgOpen;          /* Invoke start/open/xdg-open in output_reset() */
  u8 nEqpLevel;          /* Depth of the EQP output graph */
  unsigned mEqpLines;    /* Mask of veritical lines in the EQP output graph */
  int outCount;          /* Revert to stdout when reaching zero */

#endif
  ExpertInfo expert;        /* Valid if previous command was ".expert OPT..." */
};


/* Allowed values for ShellState.autoEQP
*/
#define AUTOEQP_off      0
#define AUTOEQP_on       1
#define AUTOEQP_trigger  2
#define AUTOEQP_full     3

/* Allowed values for ShellState.openMode
*/
#define SHELL_OPEN_UNSPEC     0      /* No open-mode specified */
#define SHELL_OPEN_NORMAL     1      /* Normal database file */
#define SHELL_OPEN_APPENDVFS  2      /* Use appendvfs */
#define SHELL_OPEN_ZIPFILE    3      /* Use the zipfile virtual table */

  }
  return 1;
}

/*
** Add a new entry to the EXPLAIN QUERY PLAN data
*/
static void eqp_append(ShellState *p, int iSelectId, const char *zText){
  EQPGraphRow *pNew;
  int nText = strlen30(zText);



  pNew = sqlite3_malloc64( sizeof(*pNew) + nText );
  if( pNew==0 ) shell_out_of_memory();

  pNew->iSelectId = iSelectId;
  memcpy(pNew->zText, zText, nText+1);
  pNew->pNext = 0;
  if( p->sGraph.pLast ){
    p->sGraph.pLast->pNext = pNew;
  }else{
    p->sGraph.pRow = pNew;
  }

  for(pRow = p->sGraph.pRow; pRow; pRow = pNext){
    pNext = pRow->pNext;
    sqlite3_free(pRow);
  }
  memset(&p->sGraph, 0, sizeof(p->sGraph));
}

/* Return the next EXPLAIN QUERY PLAN line with iSelectId that occurs after
** pOld, or return the first such line if pOld is NULL
*/
static EQPGraphRow *eqp_next_row(ShellState *p, int iSelectId, EQPGraphRow *pOld){
  EQPGraphRow *pRow = pOld ? pOld->pNext : p->sGraph.pRow;
  while( pRow && pRow->iSelectId!=iSelectId ) pRow = pRow->pNext;
  return pRow;
}

/* Render a single level of the graph shell having iSelectId.  Called
** recursively to render sublevels.
*/
static void eqp_render_level(ShellState *p, int iSelectId){
  EQPGraphRow *pRow, *pNext;
  int i;
  int n = strlen30(p->sGraph.zPrefix);
  char *z;
  for(pRow = eqp_next_row(p, iSelectId, 0); pRow; pRow = pNext){
    pNext = eqp_next_row(p, iSelectId, pRow);
    z = pRow->zText;
    utf8_printf(p->out, "%s%s%s\n", p->sGraph.zPrefix, pNext ? "|--" : "`--", z);
    if( n<sizeof(p->sGraph.zPrefix)-7 && (z = strstr(z, " SUBQUER"))!=0 ){
      memcpy(&p->sGraph.zPrefix[n], pNext ? "|  " : "   ", 4);
      if( strncmp(z, " SUBQUERY ", 9)==0 && (i = atoi(z+10))>iSelectId ){
        eqp_render_level(p, i);
      }else if( strncmp(z, " SUBQUERIES ", 12)==0 ){
        i = atoi(z+12);
        if( i>iSelectId ){
          utf8_printf(p->out, "%s|--SUBQUERY %d\n", p->sGraph.zPrefix, i);
          memcpy(&p->sGraph.zPrefix[n+3],"|  ",4);
          eqp_render_level(p, i);
        }
        z = strstr(z, " AND ");
        if( z && (i = atoi(z+5))>iSelectId ){
          p->sGraph.zPrefix[n+3] = 0;
          utf8_printf(p->out, "%s`--SUBQUERY %d\n", p->sGraph.zPrefix, i);
          memcpy(&p->sGraph.zPrefix[n+3],"   ",4);
          eqp_render_level(p, i);
        }
      }
      p->sGraph.zPrefix[n] = 0;
    }
  }
}

/*
** Display and reset the EXPLAIN QUERY PLAN data

        if( i>0 ) utf8_printf(p->out, "%s", p->colSeparator);
        utf8_printf(p->out,"%s",azArg[i] ? azArg[i] : p->nullValue);
      }
      utf8_printf(p->out, "%s", p->rowSeparator);
      break;
    }
    case MODE_EQP: {
      eqp_append(p, atoi(azArg[0]), azArg[3]);
      break;
    }
  }
  return 0;
}

/*

          sqlite3_db_config(db, SQLITE_DBCONFIG_TRIGGER_EQP, 1, 0);
        }
        zEQP = sqlite3_mprintf("EXPLAIN QUERY PLAN %s", zStmtSql);
        rc = sqlite3_prepare_v2(db, zEQP, -1, &pExplain, 0);
        if( rc==SQLITE_OK ){
          while( sqlite3_step(pExplain)==SQLITE_ROW ){
            const char *zEQPLine = (const char*)sqlite3_column_text(pExplain,3);
            int iSelectId = sqlite3_column_int(pExplain, 0);

            if( zEQPLine[0]=='-' ) eqp_render(pArg);
            eqp_append(pArg, iSelectId, zEQPLine);
          }
          eqp_render(pArg);
        }
        sqlite3_finalize(pExplain);
        sqlite3_free(zEQP);
        if( pArg->autoEQP>=AUTOEQP_full ){
          /* Also do an EXPLAIN for ".eqp full" mode */

      raw_printf(stderr, "Usage: .echo on|off\n");
      rc = 1;
    }
  }else

  if( c=='e' && strncmp(azArg[0], "eqp", n)==0 ){
    if( nArg==2 ){

      if( strcmp(azArg[1],"full")==0 ){
        p->autoEQP = AUTOEQP_full;
      }else if( strcmp(azArg[1],"trigger")==0 ){
        p->autoEQP = AUTOEQP_trigger;



      }else{
        p->autoEQP = (u8)booleanValue(azArg[1]);
      }
    }else{
      raw_printf(stderr, "Usage: .eqp off|on|trigger|full\n");
      rc = 1;
    }

      unsigned notIndexed :1;    /* True if there is a NOT INDEXED clause */
      unsigned isIndexedBy :1;   /* True if there is an INDEXED BY clause */
      unsigned isTabFunc :1;     /* True if table-valued-function syntax */
      unsigned isCorrelated :1;  /* True if sub-query is correlated */
      unsigned viaCoroutine :1;  /* Implemented as a co-routine */
      unsigned isRecursive :1;   /* True for recursive reference in WITH */
    } fg;
#ifndef SQLITE_OMIT_EXPLAIN
    u8 iSelectId;     /* If pSelect!=0, the id of the sub-select in EQP */
#endif
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
    union {
      char *zIndexedBy;    /* Identifier from "INDEXED BY <zIndex>" clause */
      ExprList *pFuncArg;  /* Arguments to table-valued-function */

  ExprList *pEList;      /* The fields of the result */
  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
  LogEst nSelectRow;     /* Estimated number of result rows */
  u32 selFlags;          /* Various SF_* values */
  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
#if SELECTTRACE_ENABLED
  char zSelName[12];     /* Symbolic name of this SELECT use for debugging */


  u32 iSelectId;         /* EXPLAIN QUERY PLAN select ID */
#endif
  int addrOpenEphm[2];   /* OP_OpenEphem opcodes related to this select */
  SrcList *pSrc;         /* The FROM clause */
  Expr *pWhere;          /* The WHERE clause */
  ExprList *pGroupBy;    /* The GROUP BY clause */
  Expr *pHaving;         /* The HAVING clause */

  u8 explain;               /* True if the EXPLAIN flag is found on the query */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  u8 declareVtab;           /* True if inside sqlite3_declare_vtab() */
  int nVtabLock;            /* Number of virtual tables to lock */
#endif
  int nHeight;              /* Expression tree height of current sub-select */
#ifndef SQLITE_OMIT_EXPLAIN
  int iSelectId;            /* ID of current select for EXPLAIN output */
  int iNextSelectId;        /* Next available select ID for EXPLAIN output */
#endif
  VList *pVList;            /* Mapping between variable names and numbers */
  Vdbe *pReprepare;         /* VM being reprepared (sqlite3Reprepare()) */
  const char *zTail;        /* All SQL text past the last semicolon parsed */
  Table *pNewTable;         /* A table being constructed by CREATE TABLE */
  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */

#if defined(SQLITE_DEBUG) && !defined(SQLITE_TEST_REALLOC_STRESS)
  void sqlite3VdbeVerifyNoMallocRequired(Vdbe *p, int N);
  void sqlite3VdbeVerifyNoResultRow(Vdbe *p);
#else
# define sqlite3VdbeVerifyNoMallocRequired(A,B)
# define sqlite3VdbeVerifyNoResultRow(A)
#endif
VdbeOp *sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp, int iLineno);














void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
void sqlite3VdbeChangeOpcode(Vdbe*, u32 addr, u8);
void sqlite3VdbeChangeP1(Vdbe*, u32 addr, int P1);
void sqlite3VdbeChangeP2(Vdbe*, u32 addr, int P2);
void sqlite3VdbeChangeP3(Vdbe*, u32 addr, int P3);
void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
void sqlite3VdbeJumpHere(Vdbe*, int addr);

  int p4type          /* P4 operand type */
){
  char *p4copy = sqlite3DbMallocRawNN(sqlite3VdbeDb(p), 8);
  if( p4copy ) memcpy(p4copy, zP4, 8);
  return sqlite3VdbeAddOp4(p, op, p1, p2, p3, p4copy, p4type);
}












































/*
** Add an OP_ParseSchema opcode.  This routine is broken out from
** sqlite3VdbeAddOp4() since it needs to also needs to mark all btrees
** as having been used.
**
** The zWhere string must have been obtained from sqlite3_malloc().
** This routine will take ownership of the allocated memory.

#if !defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_STMT_SCANSTATUS)
  if( sqlite3ParseToplevel(pParse)->explain==2 )
#endif
  {
    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
    sqlite3 *db = pParse->db;     /* Database handle */
    int iId = pParse->iSelectId;  /* Select id (left-most output column) */
    int isSearch;                 /* True for a SEARCH. False for SCAN. */
    WhereLoop *pLoop;             /* The controlling WhereLoop object */
    u32 flags;                    /* Flags that describe this loop */
    char *zMsg;                   /* Text to add to EQP output */
    StrAccum str;                 /* EQP output string */
    char zBuf[100];               /* Initial space for EQP output string */

    pLoop = pLevel->pWLoop;
    flags = pLoop->wsFlags;
    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_OR_SUBCLAUSE) ) return 0;

    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));

    sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
    sqlite3StrAccumAppendAll(&str, isSearch ? "SEARCH" : "SCAN");
    if( pItem->pSelect ){
      sqlite3XPrintf(&str, " SUBQUERY %d", pItem->iSelectId);
    }else{
      sqlite3XPrintf(&str, " TABLE %s", pItem->zName);
    }

    if( pItem->zAlias ){
      sqlite3XPrintf(&str, " AS %s", pItem->zAlias);
    }

    if( pLoop->nOut>=10 ){
      sqlite3XPrintf(&str, " (~%llu rows)", sqlite3LogEstToInt(pLoop->nOut));
    }else{
      sqlite3StrAccumAppend(&str, " (~1 row)", 9);
    }
#endif
    zMsg = sqlite3StrAccumFinish(&str);
    ret = sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg,P4_DYNAMIC);

  }
  return ret;
}
#endif /* SQLITE_OMIT_EXPLAIN */

#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
/*