internal static bool HasAggregates(DbSelectExpression expression) { AggregateChecker checker = new AggregateChecker(); checker.Visit(expression); return(checker.hasAggregate); }
private bool CanJoinOnClient(DbSelectExpression select) { // can add singleton (1:0,1) join if no grouping/aggregates or distinct return(!select.IsDistinct && (select.GroupBy == null || select.GroupBy.Count == 0) && !AggregateChecker.HasAggregates(select)); }
private static bool CanMergeWithFrom(DbSelectExpression select, bool isTopLevel) { DbSelectExpression fromSelect = GetLeftMostSelect(select.From); if (fromSelect == null) { return(false); } if (!IsColumnProjection(fromSelect)) { return(false); } bool selHasNameMapProjection = IsNameMapProjection(select); bool selHasOrderBy = select.OrderBy != null && select.OrderBy.Count > 0; bool selHasGroupBy = select.GroupBy != null && select.GroupBy.Count > 0; bool selHasAggregates = AggregateChecker.HasAggregates(select); bool frmHasOrderBy = fromSelect.OrderBy != null && fromSelect.OrderBy.Count > 0; bool frmHasGroupBy = fromSelect.GroupBy != null && fromSelect.GroupBy.Count > 0; // both cannot have orderby if (selHasOrderBy && frmHasOrderBy) { return(false); } // both cannot have groupby if (selHasGroupBy && frmHasGroupBy) { return(false); } // cannot move forward order-by if outer has group-by if (frmHasOrderBy && (selHasGroupBy || selHasAggregates || select.IsDistinct)) { return(false); } // cannot move forward group-by if outer has where clause if (frmHasGroupBy /*&& (select.Where != null)*/) // need to assert projection is the same in order to move group-by forward { return(false); } // cannot move forward a take if outer has take or skip or distinct if (fromSelect.Take != null && (select.Take != null || select.Skip != null || select.IsDistinct || selHasAggregates || selHasGroupBy)) { return(false); } // cannot move forward a skip if outer has skip or distinct if (fromSelect.Skip != null && (select.Skip != null || select.IsDistinct || selHasAggregates || selHasGroupBy)) { return(false); } // cannot move forward a distinct if outer has take, skip, groupby or a different projection if (fromSelect.IsDistinct && (select.Take != null || select.Skip != null || !selHasNameMapProjection || selHasGroupBy || selHasAggregates || (selHasOrderBy && !isTopLevel))) { return(false); } return(true); }
protected override Expression VisitJoin(DbJoinExpression join) { join = (DbJoinExpression)base.VisitJoin(join); if (join.Join == DbJoinType.CrossApply || join.Join == DbJoinType.OuterApply) { if (join.Right is DbTableExpression) { return(new DbJoinExpression(DbJoinType.CrossJoin, join.Left, join.Right, null)); } else { DbSelectExpression select = join.Right as DbSelectExpression; // Only consider rewriting cross apply if // 1) right side is a select // 2) other than in the where clause in the right-side select, no left-side declared aliases are referenced // 3) and has no behavior that would change semantics if the where clause is removed (like groups, aggregates, take, skip, etc). // Note: it is best to attempt this after redundant subqueries have been removed. if (select != null && select.Take == null && select.Skip == null && !AggregateChecker.HasAggregates(select) && (select.GroupBy == null || select.GroupBy.Count == 0)) { DbSelectExpression selectWithoutWhere = select.SetWhere(null); HashSet <DbTableAlias> referencedAliases = ReferencedAliasGatherer.Gather(selectWithoutWhere); HashSet <DbTableAlias> declaredAliases = DeclaredAliasGatherer.Gather(join.Left); referencedAliases.IntersectWith(declaredAliases); if (referencedAliases.Count == 0) { Expression where = select.Where; select = selectWithoutWhere; var pc = ColumnProjector.ProjectColumns(this.CanBeColumn, where, select.Columns, select.Alias, DeclaredAliasGatherer.Gather(select.From)); select = select.SetColumns(pc.Columns); where = pc.Projector; DbJoinType jt = (where == null) ? DbJoinType.CrossJoin : (join.Join == DbJoinType.CrossApply ? DbJoinType.InnerJoin : DbJoinType.LeftOuter); return(new DbJoinExpression(jt, join.Left, select, where)); } } } } return(join); }
internal static bool HasAggregates(DbSelectExpression expression) { AggregateChecker checker = new AggregateChecker(); checker.Visit(expression); return checker.hasAggregate; }