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Overview
Comment:Assert that if two functions compare equal in every other way, then they must both have OVER clauses, or neither has an OVER clause. Use this fact to simplify expression comparison.
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SHA3-256: 52559ad58ce412af40f1f34e80bfe9fadc6a93f3ca0cfaf69f94d615bbb99831
User & Date: drh 2018-07-10 07:25:42
Context
2018-07-10
07:39
Fix a harmless warning about comment formatting in the previous check-in. Simplify the ORDER BY dereferencing logic so that it avoids unreachable branches. check-in: 0f6ec605 user: drh tags: trunk
07:25
Assert that if two functions compare equal in every other way, then they must both have OVER clauses, or neither has an OVER clause. Use this fact to simplify expression comparison. check-in: 52559ad5 user: drh tags: trunk
06:47
Enhance the sqlite3ExprCompare() routine so that it knows to compare the OVER clause of window functions. check-in: 0a7649af user: drh tags: trunk
Changes
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Changes to src/expr.c.

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    assert( (combinedFlags & EP_Reduced)==0 );
    if( pA->op!=TK_STRING && pA->op!=TK_TRUEFALSE ){
      if( pA->iColumn!=pB->iColumn ) return 2;
      if( pA->iTable!=pB->iTable 
       && (pA->iTable!=iTab || NEVER(pB->iTable>=0)) ) return 2;
    }
#ifndef SQLITE_OMIT_WINDOWFUNC










    if( pA->pWin!=0 ){
      if( pB->pWin==0 ) return 2;
      if( sqlite3WindowCompare(pParse,pA->pWin,pB->pWin)!=0 ) return 2;
    }else if( pB->pWin!=0 ){
      return 2;
    }
#endif
  }
  return 0;
}

/*







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    assert( (combinedFlags & EP_Reduced)==0 );
    if( pA->op!=TK_STRING && pA->op!=TK_TRUEFALSE ){
      if( pA->iColumn!=pB->iColumn ) return 2;
      if( pA->iTable!=pB->iTable 
       && (pA->iTable!=iTab || NEVER(pB->iTable>=0)) ) return 2;
    }
#ifndef SQLITE_OMIT_WINDOWFUNC
    /* Justification for the assert():
    /* window functions have p->op==TK_FUNCTION but aggregate functions
    ** have p->op==TK_AGG_FUNCTION.  So any comparison between an aggregate
    ** function and a window function should have failed before reaching
    ** this point.  And, it is not possible to have a window function and
    ** a scalar function with the same name and number of arguments.  So
    ** if we reach this point, either A and B both window functions or
    ** neither are a window functions. */
    assert( (pA->pWin==0)==(pB->pWin==0) );

    if( pA->pWin!=0 ){

      if( sqlite3WindowCompare(pParse,pA->pWin,pB->pWin)!=0 ) return 2;


    }
#endif
  }
  return 0;
}

/*