private void ProcessFlattenedJoin(GroupJoinClause nonAggregatingJoin, QuerySourceUsageLocator locator)
{
var nhJoin = locator.LeftJoin
? new NhOuterJoinClause(nonAggregatingJoin.JoinClause)
: (IQuerySource)nonAggregatingJoin.JoinClause;
// Need to:
// 1. Remove the group join and replace it with a join
// 2. Remove the corresponding "from" clause (the thing that was doing the flattening)
// 3. Rewrite the query model to reference the "join" rather than the "from" clause
SwapClause(nonAggregatingJoin, (IBodyClause)nhJoin);
_model.BodyClauses.Remove((IBodyClause)locator.Usages[0]);
SwapQuerySourceVisitor querySourceSwapper;
if (locator.LeftJoin)
{
// As we wrapped the join clause we have to update all references to the wrapped clause
querySourceSwapper = new SwapQuerySourceVisitor(nonAggregatingJoin.JoinClause, nhJoin);
_model.TransformExpressions(querySourceSwapper.Swap);
}
querySourceSwapper = new SwapQuerySourceVisitor(locator.Usages[0], nhJoin);
_model.TransformExpressions(querySourceSwapper.Swap);
}
private void ReWrite()
{
var aggregateDetectorResults = GetGroupJoinInformation(_groupJoinClauses);
foreach (var nonAggregatingJoin in aggregateDetectorResults.NonAggregatingClauses)
{
// Group joins get processed (currently) in one of three ways.
// Option 1: results of group join are not further referenced outside of the final projection.
// In this case, replace the group join with a join, and add a client-side grouping operator
// to build the correct hierarchy
//
// Option 2: Results of group join are only used in a plain "from" expression, such as:
// from o in db.Orders
// from p in db.Products
// join d in db.OrderLines
// on new {o.OrderId, p.ProductId} equals new {d.Order.OrderId, d.Product.ProductId}
// into details
// from d in details
// select new {o.OrderId, p.ProductId, d.UnitPrice};
// In this case, simply change the group join to a join; the results of the grouping are being
// removed by the subsequent "from"
//
// Option 3: Results of group join are only used in a "from ... DefaultIfEmpty()" construction, such as:
// from o in dc.Orders
// join v in dc.Vendors on o.VendorId equals v.Id into ov
// from x in ov.DefaultIfEmpty()
// join s in dc.Status on o.StatusId equals s.Id into os
// from y in os.DefaultIfEmpty()
// select new { o.OrderNumber, x.VendorName, y.StatusName }
// This is used to repesent an outer join, and again the "from" is removing the hierarchy. So
// simply change the group join to an outer join
_locator = new QuerySourceUsageLocator(nonAggregatingJoin);
foreach (var bodyClause in _model.BodyClauses)
{
_locator.Search(bodyClause);
}
if (IsHierarchicalJoin(nonAggregatingJoin))
{
}
else if (IsFlattenedJoin(nonAggregatingJoin))
{
ProcessFlattenedJoin(nonAggregatingJoin);
}
else if (IsOuterJoin(nonAggregatingJoin))
{
}
else
{
// Wonder what this is?
throw new NotSupportedException();
}
}
}
private void ReWrite()
{
var aggregateDetectorResults = GetGroupJoinInformation(_groupJoinClauses);
foreach (var nonAggregatingJoin in aggregateDetectorResults.NonAggregatingClauses)
{
// Group joins get processed (currently) in one of three ways.
// Option 1: results of group join are not further referenced outside of the final projection.
// In this case, replace the group join with a join, and add a client-side grouping operator
// to build the correct hierarchy
//
// Option 2: Results of group join are only used in a plain "from" expression, such as:
// from o in db.Orders
// from p in db.Products
// join d in db.OrderLines
// on new {o.OrderId, p.ProductId} equals new {d.Order.OrderId, d.Product.ProductId}
// into details
// from d in details
// select new {o.OrderId, p.ProductId, d.UnitPrice};
// In this case, simply change the group join to a join; the results of the grouping are being
// removed by the subsequent "from"
//
// Option 3: Results of group join are only used in a "from ... DefaultIfEmpty()" construction, such as:
// from o in dc.Orders
// join v in dc.Vendors on o.VendorId equals v.Id into ov
// from x in ov.DefaultIfEmpty()
// join s in dc.Status on o.StatusId equals s.Id into os
// from y in os.DefaultIfEmpty()
// select new { o.OrderNumber, x.VendorName, y.StatusName }
// This is used to repesent an outer join, and again the "from" is removing the hierarchy. So
// simply change the group join to an outer join
_locator = new QuerySourceUsageLocator(nonAggregatingJoin);
foreach (var bodyClause in _model.BodyClauses)
{
_locator.Search(bodyClause);
}
if (IsHierarchicalJoin(nonAggregatingJoin))
{
}
else if (IsFlattenedJoin(nonAggregatingJoin))
{
ProcessFlattenedJoin(nonAggregatingJoin);
}
else if (IsOuterJoin(nonAggregatingJoin))
{
}
else
{
// Wonder what this is?
throw new NotSupportedException();
}
}
}
private bool IsFlattenedJoin(GroupJoinClause nonAggregatingJoin, QuerySourceUsageLocator locator)
{
if (locator.Usages.Count == 1)
{
var from = locator.Usages[0] as AdditionalFromClause;
if (from != null)
{
return(true);
}
}
return(false);
}
private bool IsHierarchicalJoin(GroupJoinClause nonAggregatingJoin, QuerySourceUsageLocator locator)
{
return(locator.Usages.Count == 0);
}
private static bool IsHierarchicalJoin(QuerySourceUsageLocator locator)
{
return(locator.Usages.Count == 0);
}
private static bool IsFlattenedJoin(QuerySourceUsageLocator locator)
{
return(locator.Usages.Count == 1 && locator.Usages[0] is AdditionalFromClause);
}
private static bool IsOuterJoin(QuerySourceUsageLocator locator)
{
return(false);
}
