static bool CheckColumn(SelectQuery.Column column, ISqlExpression expr, SelectQuery query, bool optimizeValues, bool optimizeColumns)
{
if (expr is SqlField || expr is SelectQuery.Column)
{
return(false);
}
if (expr is SqlValue)
{
return(!optimizeValues && 1.Equals(((SqlValue)expr).Value));
}
if (expr is SqlBinaryExpression)
{
var e = (SqlBinaryExpression)expr;
if (e.Operation == "*" && e.Expr1 is SqlValue)
{
var value = (SqlValue)e.Expr1;
if (value.Value is int && (int)value.Value == -1)
{
return(CheckColumn(column, e.Expr2, query, optimizeValues, optimizeColumns));
}
}
}
var visitor = new QueryVisitor();
if (optimizeColumns &&
QueryVisitor.Find(expr, e => e is SelectQuery || IsAggregationFunction(e)) == null)
{
var n = 0;
var q = query.ParentSelect ?? query;
visitor.VisitAll(q, e => { if (e == column)
{
n++;
}
});
return(n > 2);
}
return(true);
}
internal void ResolveWeakJoins(List <ISqlTableSource> tables)
{
Func <SelectQuery.TableSource, bool> findTable = null; findTable = table =>
{
if (tables.Contains(table.Source))
{
return(true);
}
foreach (var join in table.Joins)
{
if (findTable(join.Table))
{
join.IsWeak = false;
return(true);
}
}
if (table.Source is SelectQuery)
{
foreach (var t in ((SelectQuery)table.Source).From.Tables)
{
if (findTable(t))
{
return(true);
}
}
}
return(false);
};
var areTablesCollected = false;
_selectQuery.ForEachTable(table =>
{
for (var i = 0; i < table.Joins.Count; i++)
{
var join = table.Joins[i];
if (join.IsWeak)
{
if (!areTablesCollected)
{
areTablesCollected = true;
Action <IQueryElement> tableCollector = expr =>
{
var field = expr as SqlField;
if (field != null && !tables.Contains(field.Table))
{
tables.Add(field.Table);
}
};
var visitor = new QueryVisitor();
visitor.VisitAll(_selectQuery.Select, tableCollector);
visitor.VisitAll(_selectQuery.Where, tableCollector);
visitor.VisitAll(_selectQuery.GroupBy, tableCollector);
visitor.VisitAll(_selectQuery.Having, tableCollector);
visitor.VisitAll(_selectQuery.OrderBy, tableCollector);
if (_selectQuery.IsInsert)
{
visitor.VisitAll(_selectQuery.Insert, tableCollector);
}
if (_selectQuery.IsUpdate)
{
visitor.VisitAll(_selectQuery.Update, tableCollector);
}
if (_selectQuery.IsDelete)
{
visitor.VisitAll(_selectQuery.Delete, tableCollector);
}
visitor.VisitAll(_selectQuery.From, expr =>
{
var tbl = expr as SqlTable;
if (tbl != null && tbl.TableArguments != null)
{
var v = new QueryVisitor();
foreach (var arg in tbl.TableArguments)
{
v.VisitAll(arg, tableCollector);
}
}
});
}
if (findTable(join.Table))
{
join.IsWeak = false;
}
else
{
table.Joins.RemoveAt(i);
i--;
}
}
}
}, new HashSet <SelectQuery>());
}