def get_logical_plan(self, body):
if isinstance(body, UnionBlock):
subplans = []
for ggp in body.triples:
subplan = self.get_logical_plan(ggp)
if subplan:
subplans.append(subplan)
if len(subplans) == 1:
# No need for an additional union here
return subplans[0]
else:
return LogicalUnion(subplans, Xunion)
elif isinstance(body, JoinBlock):
if body.bgp:
l_plan = self.iterative_dynamic_programming1(body.triples)
elif len(body.triples) == 1:
return self.get_logical_plan(body.triples[0])
else:
left_plan = self.get_logical_plan(body.triples[0])
right_plan = self.get_logical_plan(body.triples[1])
l_plan = LogicalPlan(left_plan, right_plan, Fjoin)
return l_plan
elif isinstance(body, Optional):
plan = self.get_logical_plan(body.triples)
return plan
def decompostion_to_plan(self, decomposition):
access_plans = []
filters = []
for subplan in decomposition:
if isinstance(subplan, Filter):
filters.append(subplan)
else:
if isinstance(subplan, BGP):
access_plans.append(LogicalPlan(subplan))
else:
access_plans.append(LogicalPlan(subplan))
self.bgp_count.append(float(len(subplan)))
todo = sorted(access_plans, key=lambda x: x.cardinality)
plan = todo[0]
todo.remove(plan)
root = True
while len(todo):
for i in range(len(todo)):
if len(plan.variables.intersection(todo[i].variables)) > 0:
join_operator = self.get_physical_join_operator(
plan, todo[i])
if root and plan.is_basic_graph_pattern and join_operator == Xnjoin:
plan = LogicalUnion([plan])
plan = LogicalPlan(plan, todo[i], join_operator)
plan.compute_cardinality(self.cardinality_estimation)
todo.remove(todo[i])
root = False
break
else:
# In case we cannot find another join able triple pattern
next_tp = todo[0]
join_operator = self.get_physical_join_operator(plan, next_tp)
plan = LogicalPlan(plan, next_tp, join_operator)
plan.compute_cardinality(self.cardinality_estimation)
todo.remove(next_tp)
plan.filters = filters
return plan
def get_logical_plan_simple(self, body):
if isinstance(body, UnionBlock):
subplans = []
for ggp in body.triples:
subplan = self.get_logical_plan(ggp)
if subplan:
subplans.append(subplan)
if len(subplans) == 1:
# No need for an additional union here
return subplans[0]
else:
return LogicalUnion(subplans, Xunion)
elif isinstance(body, JoinBlock):
if body.bgp:
l_plan = self.optimize_bgp(body.triples)
elif len(body.triples) == 1:
return self.get_logical_plan(body.triples[0])
elif len(body.triples) == 2 and isinstance(body.triples[1],
Optional):
# Get operator for Optional
# TODO: Handle case with several optionals
left_plan = self.get_logical_plan(body.triples[0])
right_plan = self.get_logical_plan(body.triples[1])
operator = self.get_optional_operator(left_plan, right_plan)
l_plan = LogicalPlan(left_plan, right_plan, operator)
return l_plan
else:
left_plan = self.get_logical_plan(body.triples[0])
right_plan = self.get_logical_plan(body.triples[1])
l_plan = LogicalPlan(left_plan, right_plan, Fjoin)
return l_plan
elif isinstance(body, Optional):
plan = self.get_logical_plan(body.triples)
return plan
return None
def union_subplans(self, subplans):
if len(subplans) == 1:
return subplans[0]
else:
return LogicalUnion(subplans, Xunion)