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Overview
Comment:Improved substitution logic in the query flattener. Saves code space, and (more importantly) works correctly with table-valued functions.
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SHA1:3d0bd95e977db50c314d33ec292f99e0539d7b4a
User & Date: drh 2015-10-11 19:46:59
Context
2015-10-11
20:08
Remove an unreachable branch in the query flattener substitution logic. check-in: 46ee3453 user: drh tags: trunk
19:46
Improved substitution logic in the query flattener. Saves code space, and (more importantly) works correctly with table-valued functions. check-in: 3d0bd95e user: drh tags: trunk
2015-10-10
16:41
Work around a "security feature" bug in memcpy() on OpenBSD. check-in: fab6f090 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/select.c.

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  return pParse->nErr!=0;
}
#endif

#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* Forward Declarations */
static void substExprList(sqlite3*, ExprList*, int, ExprList*);
static void substSelect(sqlite3*, Select *, int, ExprList *);

/*
** Scan through the expression pExpr.  Replace every reference to
** a column in table number iTable with a copy of the iColumn-th
** entry in pEList.  (But leave references to the ROWID column 
** unchanged.)
**
................................................................................
      sqlite3ExprDelete(db, pExpr);
      pExpr = pNew;
    }
  }else{
    pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList);
    pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList);
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
      substSelect(db, pExpr->x.pSelect, iTable, pEList);
    }else{
      substExprList(db, pExpr->x.pList, iTable, pEList);
    }
  }
  return pExpr;
}
static void substExprList(
................................................................................
    pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList);
  }
}
static void substSelect(
  sqlite3 *db,         /* Report malloc errors here */
  Select *p,           /* SELECT statement in which to make substitutions */
  int iTable,          /* Table to be replaced */
  ExprList *pEList     /* Substitute values */

){
  SrcList *pSrc;
  struct SrcList_item *pItem;
  int i;
  if( !p ) return;

  substExprList(db, p->pEList, iTable, pEList);
  substExprList(db, p->pGroupBy, iTable, pEList);
  substExprList(db, p->pOrderBy, iTable, pEList);
  p->pHaving = substExpr(db, p->pHaving, iTable, pEList);
  p->pWhere = substExpr(db, p->pWhere, iTable, pEList);
  substSelect(db, p->pPrior, iTable, pEList);
  pSrc = p->pSrc;
  assert( pSrc );  /* Even for (SELECT 1) we have: pSrc!=0 but pSrc->nSrc==0 */
  if( ALWAYS(pSrc) ){
    for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
      substSelect(db, pItem->pSelect, iTable, pEList);


    }
  }


}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */

#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** This routine attempts to flatten subqueries as a performance optimization.
** This routine returns 1 if it makes changes and 0 if no flattening occurs.
................................................................................
  Parse *pParse,       /* Parsing context */
  Select *p,           /* The parent or outer SELECT statement */
  int iFrom,           /* Index in p->pSrc->a[] of the inner subquery */
  int isAgg,           /* True if outer SELECT uses aggregate functions */
  int subqueryIsAgg    /* True if the subquery uses aggregate functions */
){
  const char *zSavedAuthContext = pParse->zAuthContext;
  Select *pParent;
  Select *pSub;       /* The inner query or "subquery" */
  Select *pSub1;      /* Pointer to the rightmost select in sub-query */
  SrcList *pSrc;      /* The FROM clause of the outer query */
  SrcList *pSubSrc;   /* The FROM clause of the subquery */
  ExprList *pList;    /* The result set of the outer query */
  int iParent;        /* VDBE cursor number of the pSub result set temp table */
  int i;              /* Loop counter */
................................................................................
    **
    ** Example:
    **
    **    SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
    **
    ** The outer query has 3 slots in its FROM clause.  One slot of the
    ** outer query (the middle slot) is used by the subquery.  The next
    ** block of code will expand the out query to 4 slots.  The middle
    ** slot is expanded to two slots in order to make space for the
    ** two elements in the FROM clause of the subquery.
    */
    if( nSubSrc>1 ){
      pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1);
      if( db->mallocFailed ){
        break;
      }
    }
................................................................................
    for(i=0; i<pList->nExpr; i++){
      if( pList->a[i].zName==0 ){
        char *zName = sqlite3DbStrDup(db, pList->a[i].zSpan);
        sqlite3Dequote(zName);
        pList->a[i].zName = zName;
      }
    }
    substExprList(db, pParent->pEList, iParent, pSub->pEList);
    if( isAgg ){
      substExprList(db, pParent->pGroupBy, iParent, pSub->pEList);
      pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList);
    }
    if( pSub->pOrderBy ){
      /* At this point, any non-zero iOrderByCol values indicate that the
      ** ORDER BY column expression is identical to the iOrderByCol'th
      ** expression returned by SELECT statement pSub. Since these values
      ** do not necessarily correspond to columns in SELECT statement pParent,
      ** zero them before transfering the ORDER BY clause.
      **
................................................................................
      for(i=0; i<pOrderBy->nExpr; i++){
        pOrderBy->a[i].u.x.iOrderByCol = 0;
      }
      assert( pParent->pOrderBy==0 );
      assert( pSub->pPrior==0 );
      pParent->pOrderBy = pOrderBy;
      pSub->pOrderBy = 0;
    }else if( pParent->pOrderBy ){
      substExprList(db, pParent->pOrderBy, iParent, pSub->pEList);
    }
    if( pSub->pWhere ){
      pWhere = sqlite3ExprDup(db, pSub->pWhere, 0);
    }else{
      pWhere = 0;
    }
    if( subqueryIsAgg ){
      assert( pParent->pHaving==0 );
      pParent->pHaving = pParent->pWhere;
      pParent->pWhere = pWhere;
      pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList);
      pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving, 
                                  sqlite3ExprDup(db, pSub->pHaving, 0));
      assert( pParent->pGroupBy==0 );
      pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0);
    }else{
      pParent->pWhere = substExpr(db, pParent->pWhere, iParent, pSub->pEList);
      pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere);
    }

  
    /* The flattened query is distinct if either the inner or the
    ** outer query is distinct. 
    */
    pParent->selFlags |= pSub->selFlags & SF_Distinct;
  
    /*







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  return pParse->nErr!=0;
}
#endif

#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* Forward Declarations */
static void substExprList(sqlite3*, ExprList*, int, ExprList*);
static void substSelect(sqlite3*, Select *, int, ExprList*, int);

/*
** Scan through the expression pExpr.  Replace every reference to
** a column in table number iTable with a copy of the iColumn-th
** entry in pEList.  (But leave references to the ROWID column 
** unchanged.)
**
................................................................................
      sqlite3ExprDelete(db, pExpr);
      pExpr = pNew;
    }
  }else{
    pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList);
    pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList);
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
      substSelect(db, pExpr->x.pSelect, iTable, pEList, 1);
    }else{
      substExprList(db, pExpr->x.pList, iTable, pEList);
    }
  }
  return pExpr;
}
static void substExprList(
................................................................................
    pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList);
  }
}
static void substSelect(
  sqlite3 *db,         /* Report malloc errors here */
  Select *p,           /* SELECT statement in which to make substitutions */
  int iTable,          /* Table to be replaced */
  ExprList *pEList,    /* Substitute values */
  int doPrior          /* Do substitutes on p->pPrior too */
){
  SrcList *pSrc;
  struct SrcList_item *pItem;
  int i;
  if( !p ) return;
  do{
    substExprList(db, p->pEList, iTable, pEList);
    substExprList(db, p->pGroupBy, iTable, pEList);
    substExprList(db, p->pOrderBy, iTable, pEList);
    p->pHaving = substExpr(db, p->pHaving, iTable, pEList);
    p->pWhere = substExpr(db, p->pWhere, iTable, pEList);

    pSrc = p->pSrc;
    if( pSrc ){

      for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
        substSelect(db, pItem->pSelect, iTable, pEList, 1);
        if( pItem->fg.isTabFunc ){
          substExprList(db, pItem->u1.pFuncArg, iTable, pEList);
        }
      }
    }
  }while( doPrior && (p = p->pPrior)!=0 );
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */

#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** This routine attempts to flatten subqueries as a performance optimization.
** This routine returns 1 if it makes changes and 0 if no flattening occurs.
................................................................................
  Parse *pParse,       /* Parsing context */
  Select *p,           /* The parent or outer SELECT statement */
  int iFrom,           /* Index in p->pSrc->a[] of the inner subquery */
  int isAgg,           /* True if outer SELECT uses aggregate functions */
  int subqueryIsAgg    /* True if the subquery uses aggregate functions */
){
  const char *zSavedAuthContext = pParse->zAuthContext;
  Select *pParent;    /* Current UNION ALL term of the other query */
  Select *pSub;       /* The inner query or "subquery" */
  Select *pSub1;      /* Pointer to the rightmost select in sub-query */
  SrcList *pSrc;      /* The FROM clause of the outer query */
  SrcList *pSubSrc;   /* The FROM clause of the subquery */
  ExprList *pList;    /* The result set of the outer query */
  int iParent;        /* VDBE cursor number of the pSub result set temp table */
  int i;              /* Loop counter */
................................................................................
    **
    ** Example:
    **
    **    SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
    **
    ** The outer query has 3 slots in its FROM clause.  One slot of the
    ** outer query (the middle slot) is used by the subquery.  The next
    ** block of code will expand the outer query FROM clause to 4 slots.
    ** The middle slot is expanded to two slots in order to make space
    ** for the two elements in the FROM clause of the subquery.
    */
    if( nSubSrc>1 ){
      pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1);
      if( db->mallocFailed ){
        break;
      }
    }
................................................................................
    for(i=0; i<pList->nExpr; i++){
      if( pList->a[i].zName==0 ){
        char *zName = sqlite3DbStrDup(db, pList->a[i].zSpan);
        sqlite3Dequote(zName);
        pList->a[i].zName = zName;
      }
    }





    if( pSub->pOrderBy ){
      /* At this point, any non-zero iOrderByCol values indicate that the
      ** ORDER BY column expression is identical to the iOrderByCol'th
      ** expression returned by SELECT statement pSub. Since these values
      ** do not necessarily correspond to columns in SELECT statement pParent,
      ** zero them before transfering the ORDER BY clause.
      **
................................................................................
      for(i=0; i<pOrderBy->nExpr; i++){
        pOrderBy->a[i].u.x.iOrderByCol = 0;
      }
      assert( pParent->pOrderBy==0 );
      assert( pSub->pPrior==0 );
      pParent->pOrderBy = pOrderBy;
      pSub->pOrderBy = 0;


    }

    pWhere = sqlite3ExprDup(db, pSub->pWhere, 0);



    if( subqueryIsAgg ){
      assert( pParent->pHaving==0 );
      pParent->pHaving = pParent->pWhere;
      pParent->pWhere = pWhere;

      pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving, 
                                  sqlite3ExprDup(db, pSub->pHaving, 0));
      assert( pParent->pGroupBy==0 );
      pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0);
    }else{

      pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere);
    }
    substSelect(db, pParent, iParent, pSub->pEList, 0);
  
    /* The flattened query is distinct if either the inner or the
    ** outer query is distinct. 
    */
    pParent->selFlags |= pSub->selFlags & SF_Distinct;
  
    /*

Changes to test/tabfunc01.test.

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} {1 {'v2' is not a function}}

do_execsql_test tabfunc01-2.1 {
  CREATE TABLE t1(x);
  INSERT INTO t1(x) VALUES(2),(3);
  SELECT *, '|' FROM t1, generate_series(1,x) ORDER BY 1, 2
} {2 1 | 2 2 | 3 1 | 3 2 | 3 3 |}





do_execsql_test tabfunc01-2.2 {
  SELECT * FROM generate_series() LIMIT 5;
} {0 1 2 3 4}

do_execsql_test tabfunc01-3.1 {
  SELECT DISTINCT value FROM generate_series(1,x), t1 ORDER BY 1;
} {1 2 3}








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} {1 {'v2' is not a function}}

do_execsql_test tabfunc01-2.1 {
  CREATE TABLE t1(x);
  INSERT INTO t1(x) VALUES(2),(3);
  SELECT *, '|' FROM t1, generate_series(1,x) ORDER BY 1, 2
} {2 1 | 2 2 | 3 1 | 3 2 | 3 3 |}
do_execsql_test tabfunc01-2.2 {
  SELECT *, '|' FROM (SELECT x FROM t1) AS y, generate_series(1,y.x)
  ORDER BY 1, 2;
} {2 1 | 2 2 | 3 1 | 3 2 | 3 3 |}

do_execsql_test tabfunc01-2.50 {
  SELECT * FROM generate_series() LIMIT 5;
} {0 1 2 3 4}

do_execsql_test tabfunc01-3.1 {
  SELECT DISTINCT value FROM generate_series(1,x), t1 ORDER BY 1;
} {1 2 3}