// initialization: enqueue all vertex nodes
protected void InitByInsertBasicTables(JoinGraph graph)
{
graph_ = graph;
foreach (var logic in graph.vertices_)
{
BitVector contained = 1 << graph.vertices_.IndexOf(logic);
logic.tableContained_ = contained;
if (graph.memo_ is null)
{
bestTree_[contained] = new PhysicScanTable(logic);
}
else
{
// vertices are already inserted into memo
var cgroup = graph.memo_.LookupCGroup(logic);
var logicref = new LogicMemoRef(cgroup);
bestTree_[contained] = new PhysicMemoRef(logicref);
}
}
}
override internal PhysicNode Run(JoinGraph graph, BigInteger expectC1)
{
int ntables = graph.vertices_.Count;
var Trees = new List <PhysicNode>();
Console.WriteLine("GOO #tables: " + ntables);
// Treees = {R1, R2, ..., Rn}
graph_ = graph;
foreach (var logic in graph.vertices_)
{
BitVector contained = 1 << graph.vertices_.IndexOf(logic);
logic.tableContained_ = contained;
if (graph.memo_ is null)
{
Trees.Add(new PhysicScanTable(logic));
}
else
{
// vertices are already inserted into memo
var cgroup = graph.memo_.LookupCGroup(logic);
var logicref = new LogicMemoRef(cgroup);
Trees.Add(new PhysicMemoRef(logicref));
}
}
while (Trees.Count != 1)
{
PhysicNode Ti = null, Tj = null;
PhysicNode bestJoin = null;
// find Ti, Tj in Trees s.t. i < j (avoid duplicates) and TixTj is minimal
for (int i = 0; i < Trees.Count; i++)
{
for (int j = i + 1; j < Trees.Count; j++)
{
var join = CreateMinimalJoinTree(Trees[i], Trees[j], true);
if (bestJoin == null || join.Cost() < bestJoin.Cost())
{
bestJoin = join;
Ti = Trees[i];
Tj = Trees[j];
}
}
}
Debug.Assert(Ti != null && Tj != null);
Trees.Remove(Ti); Trees.Remove(Tj);
Trees.Add(bestJoin);
}
// compare with DPccp solver
// ideally, DPccp shall always generate better plans since GOO is heuristic - but DPccp does not consider
// CP, so in some cases where CP is beneficial, GOO can win
//
var result = Trees[0];
var dpccp = new DPccp().Run(graph, expectC1);
Console.WriteLine(result);
if (dpccp.InclusiveCost() < result.InclusiveCost())
{
Console.WriteLine("warning: GOO non optimal plan: {0} vs. {1}", dpccp.InclusiveCost(), result.InclusiveCost());
}
if (dpccp.Cost() > result.Cost())
{
Console.WriteLine("warning: DPCC shall consider CP in the case: {0} vs. {1}", dpccp.InclusiveCost(), result.InclusiveCost());
}
return(result);
}
