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SQLite training in Houston TX on 2019-11-05 (details)
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Overview
Comment:Do not flatten aggregate subqueries that contain min() or max() functions so that if the min()/max() are discarded by the outer query, they still function and cause non-aggregate expression to be evaluated on the minimal or maximal row.
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SHA1: 0bdf1a086b3946722f4d4b328e25917f61c14713
User & Date: drh 2014-09-15 14:46:02
Context
2014-09-15
14:59
Remove the EXPENSIVE_ASSERTS in pcache.c having to do with the pSynced field of the Pcache object, as they are incorrect, as revealed by recent pcache enhancements. check-in: 69a64560 user: drh tags: trunk
14:46
Do not flatten aggregate subqueries that contain min() or max() functions so that if the min()/max() are discarded by the outer query, they still function and cause non-aggregate expression to be evaluated on the minimal or maximal row. check-in: 0bdf1a08 user: drh tags: trunk
11:14
Adjust comments to show that subquery flattening restriction (10) was removed from the code back in 2005. This is a comment change only. check-in: 4ff0eb96 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/func.c.

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    FUNCTION(ltrim,              2, 1, 0, trimFunc         ),
    FUNCTION(rtrim,              1, 2, 0, trimFunc         ),
    FUNCTION(rtrim,              2, 2, 0, trimFunc         ),
    FUNCTION(trim,               1, 3, 0, trimFunc         ),
    FUNCTION(trim,               2, 3, 0, trimFunc         ),
    FUNCTION(min,               -1, 0, 1, minmaxFunc       ),
    FUNCTION(min,                0, 0, 1, 0                ),
    AGGREGATE(min,               1, 0, 1, minmaxStep,      minMaxFinalize ),

    FUNCTION(max,               -1, 1, 1, minmaxFunc       ),
    FUNCTION(max,                0, 1, 1, 0                ),
    AGGREGATE(max,               1, 1, 1, minmaxStep,      minMaxFinalize ),

    FUNCTION2(typeof,            1, 0, 0, typeofFunc,  SQLITE_FUNC_TYPEOF),
    FUNCTION2(length,            1, 0, 0, lengthFunc,  SQLITE_FUNC_LENGTH),
    FUNCTION(instr,              2, 0, 0, instrFunc        ),
    FUNCTION(substr,             2, 0, 0, substrFunc       ),
    FUNCTION(substr,             3, 0, 0, substrFunc       ),
    FUNCTION(printf,            -1, 0, 0, printfFunc       ),
    FUNCTION(unicode,            1, 0, 0, unicodeFunc      ),
................................................................................
  #ifndef SQLITE_OMIT_LOAD_EXTENSION
    FUNCTION(load_extension,     1, 0, 0, loadExt          ),
    FUNCTION(load_extension,     2, 0, 0, loadExt          ),
  #endif
    AGGREGATE(sum,               1, 0, 0, sumStep,         sumFinalize    ),
    AGGREGATE(total,             1, 0, 0, sumStep,         totalFinalize    ),
    AGGREGATE(avg,               1, 0, 0, sumStep,         avgFinalize    ),
 /* AGGREGATE(count,             0, 0, 0, countStep,       countFinalize  ), */
    {0,SQLITE_UTF8|SQLITE_FUNC_COUNT,0,0,0,countStep,countFinalize,"count",0,0},
    AGGREGATE(count,             1, 0, 0, countStep,       countFinalize  ),
    AGGREGATE(group_concat,      1, 0, 0, groupConcatStep, groupConcatFinalize),
    AGGREGATE(group_concat,      2, 0, 0, groupConcatStep, groupConcatFinalize),
  
    LIKEFUNC(glob, 2, &globInfo, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
  #ifdef SQLITE_CASE_SENSITIVE_LIKE
    LIKEFUNC(like, 2, &likeInfoAlt, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),







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    FUNCTION(ltrim,              2, 1, 0, trimFunc         ),
    FUNCTION(rtrim,              1, 2, 0, trimFunc         ),
    FUNCTION(rtrim,              2, 2, 0, trimFunc         ),
    FUNCTION(trim,               1, 3, 0, trimFunc         ),
    FUNCTION(trim,               2, 3, 0, trimFunc         ),
    FUNCTION(min,               -1, 0, 1, minmaxFunc       ),
    FUNCTION(min,                0, 0, 1, 0                ),
    AGGREGATE2(min,              1, 0, 1, minmaxStep,      minMaxFinalize,
                                          SQLITE_FUNC_MINMAX ),
    FUNCTION(max,               -1, 1, 1, minmaxFunc       ),
    FUNCTION(max,                0, 1, 1, 0                ),
    AGGREGATE2(max,              1, 1, 1, minmaxStep,      minMaxFinalize,
                                          SQLITE_FUNC_MINMAX ),
    FUNCTION2(typeof,            1, 0, 0, typeofFunc,  SQLITE_FUNC_TYPEOF),
    FUNCTION2(length,            1, 0, 0, lengthFunc,  SQLITE_FUNC_LENGTH),
    FUNCTION(instr,              2, 0, 0, instrFunc        ),
    FUNCTION(substr,             2, 0, 0, substrFunc       ),
    FUNCTION(substr,             3, 0, 0, substrFunc       ),
    FUNCTION(printf,            -1, 0, 0, printfFunc       ),
    FUNCTION(unicode,            1, 0, 0, unicodeFunc      ),
................................................................................
  #ifndef SQLITE_OMIT_LOAD_EXTENSION
    FUNCTION(load_extension,     1, 0, 0, loadExt          ),
    FUNCTION(load_extension,     2, 0, 0, loadExt          ),
  #endif
    AGGREGATE(sum,               1, 0, 0, sumStep,         sumFinalize    ),
    AGGREGATE(total,             1, 0, 0, sumStep,         totalFinalize    ),
    AGGREGATE(avg,               1, 0, 0, sumStep,         avgFinalize    ),
    AGGREGATE2(count,            0, 0, 0, countStep,       countFinalize,
               SQLITE_FUNC_COUNT  ),
    AGGREGATE(count,             1, 0, 0, countStep,       countFinalize  ),
    AGGREGATE(group_concat,      1, 0, 0, groupConcatStep, groupConcatFinalize),
    AGGREGATE(group_concat,      2, 0, 0, groupConcatStep, groupConcatFinalize),
  
    LIKEFUNC(glob, 2, &globInfo, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),
  #ifdef SQLITE_CASE_SENSITIVE_LIKE
    LIKEFUNC(like, 2, &likeInfoAlt, SQLITE_FUNC_LIKE|SQLITE_FUNC_CASE),

Changes to src/resolve.c.

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            ** likelihood(X,0.9375).
            ** EVIDENCE-OF: R-53436-40973 The likely(X) function is equivalent to
            ** likelihood(X,0.9375). */
            /* TUNING: unlikely() probability is 0.0625.  likely() is 0.9375 */
            pExpr->iTable = pDef->zName[0]=='u' ? 62 : 938;
          }             
        }
      }
#ifndef SQLITE_OMIT_AUTHORIZATION
      if( pDef ){
        auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);
        if( auth!=SQLITE_OK ){
          if( auth==SQLITE_DENY ){
            sqlite3ErrorMsg(pParse, "not authorized to use function: %s",
                                    pDef->zName);
            pNC->nErr++;
          }
          pExpr->op = TK_NULL;
          return WRC_Prune;
        }

        if( pDef->funcFlags & SQLITE_FUNC_CONSTANT ) ExprSetProperty(pExpr,EP_Constant);
      }
#endif
      if( is_agg && (pNC->ncFlags & NC_AllowAgg)==0 ){
        sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
        pNC->nErr++;
        is_agg = 0;
      }else if( no_such_func && pParse->db->init.busy==0 ){
        sqlite3ErrorMsg(pParse, "no such function: %.*s", nId, zId);
        pNC->nErr++;
................................................................................
        NameContext *pNC2 = pNC;
        pExpr->op = TK_AGG_FUNCTION;
        pExpr->op2 = 0;
        while( pNC2 && !sqlite3FunctionUsesThisSrc(pExpr, pNC2->pSrcList) ){
          pExpr->op2++;
          pNC2 = pNC2->pNext;
        }




        if( pNC2 ) pNC2->ncFlags |= NC_HasAgg;


        pNC->ncFlags |= NC_AllowAgg;
      }
      /* FIX ME:  Compute pExpr->affinity based on the expected return
      ** type of the function 
      */
      return WRC_Prune;
    }
................................................................................
  
    /* If there are no aggregate functions in the result-set, and no GROUP BY 
    ** expression, do not allow aggregates in any of the other expressions.
    */
    assert( (p->selFlags & SF_Aggregate)==0 );
    pGroupBy = p->pGroupBy;
    if( pGroupBy || (sNC.ncFlags & NC_HasAgg)!=0 ){

      p->selFlags |= SF_Aggregate;
    }else{
      sNC.ncFlags &= ~NC_AllowAgg;
    }
  
    /* If a HAVING clause is present, then there must be a GROUP BY clause.
    */
    if( p->pHaving && !pGroupBy ){
................................................................................
** An error message is left in pParse if anything is amiss.  The number
** if errors is returned.
*/
int sqlite3ResolveExprNames( 
  NameContext *pNC,       /* Namespace to resolve expressions in. */
  Expr *pExpr             /* The expression to be analyzed. */
){
  u8 savedHasAgg;
  Walker w;

  if( pExpr==0 ) return 0;
#if SQLITE_MAX_EXPR_DEPTH>0
  {
    Parse *pParse = pNC->pParse;
    if( sqlite3ExprCheckHeight(pParse, pExpr->nHeight+pNC->pParse->nHeight) ){
      return 1;
    }
    pParse->nHeight += pExpr->nHeight;
  }
#endif
  savedHasAgg = pNC->ncFlags & NC_HasAgg;
  pNC->ncFlags &= ~NC_HasAgg;
  memset(&w, 0, sizeof(w));
  w.xExprCallback = resolveExprStep;
  w.xSelectCallback = resolveSelectStep;
  w.pParse = pNC->pParse;
  w.u.pNC = pNC;
  sqlite3WalkExpr(&w, pExpr);
#if SQLITE_MAX_EXPR_DEPTH>0
................................................................................
  pNC->pParse->nHeight -= pExpr->nHeight;
#endif
  if( pNC->nErr>0 || w.pParse->nErr>0 ){
    ExprSetProperty(pExpr, EP_Error);
  }
  if( pNC->ncFlags & NC_HasAgg ){
    ExprSetProperty(pExpr, EP_Agg);
  }else if( savedHasAgg ){
    pNC->ncFlags |= NC_HasAgg;
  }

  return ExprHasProperty(pExpr, EP_Error);
}


/*
** Resolve all names in all expressions of a SELECT and in all
** decendents of the SELECT, including compounds off of p->pPrior,







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            ** likelihood(X,0.9375).
            ** EVIDENCE-OF: R-53436-40973 The likely(X) function is equivalent to
            ** likelihood(X,0.9375). */
            /* TUNING: unlikely() probability is 0.0625.  likely() is 0.9375 */
            pExpr->iTable = pDef->zName[0]=='u' ? 62 : 938;
          }             
        }

#ifndef SQLITE_OMIT_AUTHORIZATION

        auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);
        if( auth!=SQLITE_OK ){
          if( auth==SQLITE_DENY ){
            sqlite3ErrorMsg(pParse, "not authorized to use function: %s",
                                    pDef->zName);
            pNC->nErr++;
          }
          pExpr->op = TK_NULL;
          return WRC_Prune;
        }
#endif
        if( pDef->funcFlags & SQLITE_FUNC_CONSTANT ) ExprSetProperty(pExpr,EP_Constant);
      }

      if( is_agg && (pNC->ncFlags & NC_AllowAgg)==0 ){
        sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
        pNC->nErr++;
        is_agg = 0;
      }else if( no_such_func && pParse->db->init.busy==0 ){
        sqlite3ErrorMsg(pParse, "no such function: %.*s", nId, zId);
        pNC->nErr++;
................................................................................
        NameContext *pNC2 = pNC;
        pExpr->op = TK_AGG_FUNCTION;
        pExpr->op2 = 0;
        while( pNC2 && !sqlite3FunctionUsesThisSrc(pExpr, pNC2->pSrcList) ){
          pExpr->op2++;
          pNC2 = pNC2->pNext;
        }
        assert( pDef!=0 );
        if( pNC2 ){
          assert( SQLITE_FUNC_MINMAX==NC_MinMaxAgg );
          testcase( (pDef->funcFlags & SQLITE_FUNC_MINMAX)!=0 );
          pNC2->ncFlags |= NC_HasAgg | (pDef->funcFlags & SQLITE_FUNC_MINMAX);

        }
        pNC->ncFlags |= NC_AllowAgg;
      }
      /* FIX ME:  Compute pExpr->affinity based on the expected return
      ** type of the function 
      */
      return WRC_Prune;
    }
................................................................................
  
    /* If there are no aggregate functions in the result-set, and no GROUP BY 
    ** expression, do not allow aggregates in any of the other expressions.
    */
    assert( (p->selFlags & SF_Aggregate)==0 );
    pGroupBy = p->pGroupBy;
    if( pGroupBy || (sNC.ncFlags & NC_HasAgg)!=0 ){
      assert( NC_MinMaxAgg==SF_MinMaxAgg );
      p->selFlags |= SF_Aggregate | (sNC.ncFlags&NC_MinMaxAgg);
    }else{
      sNC.ncFlags &= ~NC_AllowAgg;
    }
  
    /* If a HAVING clause is present, then there must be a GROUP BY clause.
    */
    if( p->pHaving && !pGroupBy ){
................................................................................
** An error message is left in pParse if anything is amiss.  The number
** if errors is returned.
*/
int sqlite3ResolveExprNames( 
  NameContext *pNC,       /* Namespace to resolve expressions in. */
  Expr *pExpr             /* The expression to be analyzed. */
){
  u16 savedHasAgg;
  Walker w;

  if( pExpr==0 ) return 0;
#if SQLITE_MAX_EXPR_DEPTH>0
  {
    Parse *pParse = pNC->pParse;
    if( sqlite3ExprCheckHeight(pParse, pExpr->nHeight+pNC->pParse->nHeight) ){
      return 1;
    }
    pParse->nHeight += pExpr->nHeight;
  }
#endif
  savedHasAgg = pNC->ncFlags & (NC_HasAgg|NC_MinMaxAgg);
  pNC->ncFlags &= ~(NC_HasAgg|NC_MinMaxAgg);
  memset(&w, 0, sizeof(w));
  w.xExprCallback = resolveExprStep;
  w.xSelectCallback = resolveSelectStep;
  w.pParse = pNC->pParse;
  w.u.pNC = pNC;
  sqlite3WalkExpr(&w, pExpr);
#if SQLITE_MAX_EXPR_DEPTH>0
................................................................................
  pNC->pParse->nHeight -= pExpr->nHeight;
#endif
  if( pNC->nErr>0 || w.pParse->nErr>0 ){
    ExprSetProperty(pExpr, EP_Error);
  }
  if( pNC->ncFlags & NC_HasAgg ){
    ExprSetProperty(pExpr, EP_Agg);


  }
  pNC->ncFlags |= savedHasAgg;
  return ExprHasProperty(pExpr, EP_Error);
}


/*
** Resolve all names in all expressions of a SELECT and in all
** decendents of the SELECT, including compounds off of p->pPrior,

Changes to src/select.c.

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**  (22)  The subquery is not a recursive CTE.
**
**  (23)  The parent is not a recursive CTE, or the sub-query is not a
**        compound query. This restriction is because transforming the
**        parent to a compound query confuses the code that handles
**        recursive queries in multiSelect().
**





**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
................................................................................
     return 0;                                           /* Restriction (11) */
  }
  if( isAgg && pSub->pOrderBy ) return 0;                /* Restriction (16) */
  if( pSub->pLimit && p->pWhere ) return 0;              /* Restriction (19) */
  if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
     return 0;         /* Restriction (21) */
  }
  if( pSub->selFlags & SF_Recursive ) return 0;          /* Restriction (22)  */




  if( (p->selFlags & SF_Recursive) && pSub->pPrior ) return 0;       /* (23)  */



  /* OBSOLETE COMMENT 1:
  ** Restriction 3:  If the subquery is a join, make sure the subquery is 
  ** not used as the right operand of an outer join.  Examples of why this
  ** is not allowed:
  **
  **         t1 LEFT OUTER JOIN (t2 JOIN t3)







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**  (22)  The subquery is not a recursive CTE.
**
**  (23)  The parent is not a recursive CTE, or the sub-query is not a
**        compound query. This restriction is because transforming the
**        parent to a compound query confuses the code that handles
**        recursive queries in multiSelect().
**
**  (24)  The subquery is not an aggregate that uses the built-in min() or 
**        or max() functions.  (Without this restriction, a query like:
**        "SELECT x FROM (SELECT max(y), x FROM t1)" would not necessarily
**        return the value X for which Y was maximal.)
**
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
................................................................................
     return 0;                                           /* Restriction (11) */
  }
  if( isAgg && pSub->pOrderBy ) return 0;                /* Restriction (16) */
  if( pSub->pLimit && p->pWhere ) return 0;              /* Restriction (19) */
  if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
     return 0;         /* Restriction (21) */
  }
  testcase( pSub->selFlags & SF_Recursive );
  testcase( pSub->selFlags & SF_MinMaxAgg );
  if( pSub->selFlags & (SF_Recursive|SF_MinMaxAgg) ){
    return 0; /* Restrictions (22) and (24) */
  }
  if( (p->selFlags & SF_Recursive) && pSub->pPrior ){
    return 0; /* Restriction (23) */
  }

  /* OBSOLETE COMMENT 1:
  ** Restriction 3:  If the subquery is a join, make sure the subquery is 
  ** not used as the right operand of an outer join.  Examples of why this
  ** is not allowed:
  **
  **         t1 LEFT OUTER JOIN (t2 JOIN t3)

Changes to src/sqliteInt.h.

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#define SQLITE_FUNC_NEEDCOLL 0x020 /* sqlite3GetFuncCollSeq() might be called */
#define SQLITE_FUNC_LENGTH   0x040 /* Built-in length() function */
#define SQLITE_FUNC_TYPEOF   0x080 /* Built-in typeof() function */
#define SQLITE_FUNC_COUNT    0x100 /* Built-in count(*) aggregate */
#define SQLITE_FUNC_COALESCE 0x200 /* Built-in coalesce() or ifnull() */
#define SQLITE_FUNC_UNLIKELY 0x400 /* Built-in unlikely() function */
#define SQLITE_FUNC_CONSTANT 0x800 /* Constant inputs give a constant output */


/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Used to create a scalar function definition of a function zName 
................................................................................
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   pArg, 0, xFunc, 0, 0, #zName, 0, 0}
#define LIKEFUNC(zName, nArg, arg, flags) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|flags, \
   (void *)arg, 0, likeFunc, 0, 0, #zName, 0, 0}
#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \



   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0,0}

/*
** All current savepoints are stored in a linked list starting at
** sqlite3.pSavepoint. The first element in the list is the most recently
** opened savepoint. Savepoints are added to the list by the vdbe
** OP_Savepoint instruction.
................................................................................
  Parse *pParse;       /* The parser */
  SrcList *pSrcList;   /* One or more tables used to resolve names */
  ExprList *pEList;    /* Optional list of result-set columns */
  AggInfo *pAggInfo;   /* Information about aggregates at this level */
  NameContext *pNext;  /* Next outer name context.  NULL for outermost */
  int nRef;            /* Number of names resolved by this context */
  int nErr;            /* Number of errors encountered while resolving names */
  u8 ncFlags;          /* Zero or more NC_* flags defined below */
};

/*
** Allowed values for the NameContext, ncFlags field.




*/
#define NC_AllowAgg  0x01    /* Aggregate functions are allowed here */
#define NC_HasAgg    0x02    /* One or more aggregate functions seen */
#define NC_IsCheck   0x04    /* True if resolving names in a CHECK constraint */
#define NC_InAggFunc 0x08    /* True if analyzing arguments to an agg func */
#define NC_PartIdx   0x10    /* True if resolving a partial index WHERE */


/*
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
................................................................................
*/
#define SF_Distinct        0x0001  /* Output should be DISTINCT */
#define SF_Resolved        0x0002  /* Identifiers have been resolved */
#define SF_Aggregate       0x0004  /* Contains aggregate functions */
#define SF_UsesEphemeral   0x0008  /* Uses the OpenEphemeral opcode */
#define SF_Expanded        0x0010  /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo     0x0020  /* FROM subqueries have Table metadata */
                    /*     0x0040  NOT USED */
#define SF_Values          0x0080  /* Synthesized from VALUES clause */
                    /*     0x0100  NOT USED */
#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 */
#define SF_Compound        0x1000  /* Part of a compound query */


/*
** 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".
**







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#define SQLITE_FUNC_NEEDCOLL 0x020 /* sqlite3GetFuncCollSeq() might be called */
#define SQLITE_FUNC_LENGTH   0x040 /* Built-in length() function */
#define SQLITE_FUNC_TYPEOF   0x080 /* Built-in typeof() function */
#define SQLITE_FUNC_COUNT    0x100 /* Built-in count(*) aggregate */
#define SQLITE_FUNC_COALESCE 0x200 /* Built-in coalesce() or ifnull() */
#define SQLITE_FUNC_UNLIKELY 0x400 /* Built-in unlikely() function */
#define SQLITE_FUNC_CONSTANT 0x800 /* Constant inputs give a constant output */
#define SQLITE_FUNC_MINMAX  0x1000 /* True for min() and max() aggregates */

/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
**     Used to create a scalar function definition of a function zName 
................................................................................
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
   pArg, 0, xFunc, 0, 0, #zName, 0, 0}
#define LIKEFUNC(zName, nArg, arg, flags) \
  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|flags, \
   (void *)arg, 0, likeFunc, 0, 0, #zName, 0, 0}
#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL), \
   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0,0}
#define AGGREGATE2(zName, nArg, arg, nc, xStep, xFinal, extraFlags) \
  {nArg, SQLITE_UTF8|(nc*SQLITE_FUNC_NEEDCOLL)|extraFlags, \
   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0,0}

/*
** All current savepoints are stored in a linked list starting at
** sqlite3.pSavepoint. The first element in the list is the most recently
** opened savepoint. Savepoints are added to the list by the vdbe
** OP_Savepoint instruction.
................................................................................
  Parse *pParse;       /* The parser */
  SrcList *pSrcList;   /* One or more tables used to resolve names */
  ExprList *pEList;    /* Optional list of result-set columns */
  AggInfo *pAggInfo;   /* Information about aggregates at this level */
  NameContext *pNext;  /* Next outer name context.  NULL for outermost */
  int nRef;            /* Number of names resolved by this context */
  int nErr;            /* Number of errors encountered while resolving names */
  u16 ncFlags;         /* Zero or more NC_* flags defined below */
};

/*
** Allowed values for the NameContext, ncFlags field.
**
** Note:  NC_MinMaxAgg must have the same value as SF_MinMaxAgg and
** SQLITE_FUNC_MINMAX.
** 
*/
#define NC_AllowAgg  0x0001  /* Aggregate functions are allowed here */
#define NC_HasAgg    0x0002  /* One or more aggregate functions seen */
#define NC_IsCheck   0x0004  /* True if resolving names in a CHECK constraint */
#define NC_InAggFunc 0x0008  /* True if analyzing arguments to an agg func */
#define NC_PartIdx   0x0010  /* True if resolving a partial index WHERE */
#define NC_MinMaxAgg 0x1000  /* min/max aggregates seen.  See note above */

/*
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
................................................................................
*/
#define SF_Distinct        0x0001  /* Output should be DISTINCT */
#define SF_Resolved        0x0002  /* Identifiers have been resolved */
#define SF_Aggregate       0x0004  /* Contains aggregate functions */
#define SF_UsesEphemeral   0x0008  /* Uses the OpenEphemeral opcode */
#define SF_Expanded        0x0010  /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo     0x0020  /* FROM subqueries have Table metadata */
#define SF_Compound        0x0040  /* Part of a compound query */
#define SF_Values          0x0080  /* Synthesized from VALUES clause */
                    /*     0x0100  NOT USED */
#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 */
#define SF_MinMaxAgg       0x1000  /* Aggregate containing min() or max() */


/*
** 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".
**

Changes to test/aggnested.test.

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    INSERT INTO t2 VALUES(1);
    SELECT
     (SELECT sum(value2==xyz) FROM t2)
    FROM
     (SELECT value1 as xyz, max(x1) AS pqr
        FROM t1
       GROUP BY id1);






  }
} {0}
do_test aggnested-3.3 {
  db eval {
    DROP TABLE IF EXISTS t1;
    DROP TABLE IF EXISTS t2;
    CREATE TABLE t1(id1, value1);
    INSERT INTO t1 VALUES(4469,2),(4469,1);
    CREATE TABLE t2 (value2);







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    INSERT INTO t2 VALUES(1);
    SELECT
     (SELECT sum(value2==xyz) FROM t2)
    FROM
     (SELECT value1 as xyz, max(x1) AS pqr
        FROM t1
       GROUP BY id1);
    SELECT
     (SELECT sum(value2<>xyz) FROM t2)
    FROM
     (SELECT value1 as xyz, max(x1) AS pqr
        FROM t1
       GROUP BY id1);
  }
} {1 0}
do_test aggnested-3.3 {
  db eval {
    DROP TABLE IF EXISTS t1;
    DROP TABLE IF EXISTS t2;
    CREATE TABLE t1(id1, value1);
    INSERT INTO t1 VALUES(4469,2),(4469,1);
    CREATE TABLE t2 (value2);

Changes to test/minmax4.test.

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    INSERT INTO t1 VALUES(3,4);
    SELECT p, max(q) FROM t1;
  }
} {3 4}
do_test minmax4-1.6 {
  db eval {
    SELECT p, min(q) FROM t1;

  }
} {1 2}
do_test minmax4-1.7 {
  db eval {
    INSERT INTO t1 VALUES(5,0);
    SELECT p, max(q) FROM t1;

  }
} {3 4}
do_test minmax4-1.8 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.9 {
  db eval {
    INSERT INTO t1 VALUES(6,1);
    SELECT p, max(q) FROM t1;

  }
} {3 4}
do_test minmax4-1.10 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.11 {
  db eval {







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    INSERT INTO t1 VALUES(3,4);
    SELECT p, max(q) FROM t1;
  }
} {3 4}
do_test minmax4-1.6 {
  db eval {
    SELECT p, min(q) FROM t1;
    SELECT p FROM (SELECT p, min(q) FROM t1);
  }
} {1 2 1}
do_test minmax4-1.7 {
  db eval {
    INSERT INTO t1 VALUES(5,0);
    SELECT p, max(q) FROM t1;
    SELECT p FROM (SELECT max(q), p FROM t1);
  }
} {3 4 3}
do_test minmax4-1.8 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.9 {
  db eval {
    INSERT INTO t1 VALUES(6,1);
    SELECT p, max(q) FROM t1;
    SELECT p FROM (SELECT max(q), p FROM t1);
  }
} {3 4 3}
do_test minmax4-1.10 {
  db eval {
    SELECT p, min(q) FROM t1;
  }
} {5 0}
do_test minmax4-1.11 {
  db eval {