def pickJoinOrder(self, plan):
rels = set(plan.relations())
optPlans = {} #Map a set of relations to the optimized plan
#toBeProcessed = [] #Set of relations pending processing
self.combsTried = 0
self.plansProcessed = 0
for r in rels:
set_r = frozenset({r})
#toBeProcessed.append(set_r)
newScan = TableScan(r, self.db.relationSchema(r))
newScan.prepare(self.db)
optPlans[set_r] = newScan
#For each join operator, fetch its relative relations
#Map a set of relations to (relative relations, operator)
joinMap = {}
for (_, op) in plan.flatten():
if isinstance(op, Join):
relativeR = self.relativeRelations(rels, op)
for r in [frozenset({r}) for r in relativeR]:
if r in joinMap.keys():
joinMap[r].append((relativeR, op))
else:
joinMap[r] = [(relativeR, op)]
n = len(rels)
for i in range(2, n + 1):
for union in [frozenset(union) for union in self.kRelsComb(i, rels)]:
for right in [frozenset(right) for right in self.kRelsComb(1, union)]:
left = frozenset(union - right)
for t in left:
self.combsTried += 1
value = joinMap[frozenset({t})]
if not value:
continue
else:
for tuple in value:
if not (set(tuple[0]).issubset(union) and left in optPlans and right in optPlans):
continue
self.plansProcessed += 1
newJoin = Join(optPlans[left], optPlans[right], expr=tuple[1].joinExpr, method="block-nested-loops")
newJoin.prepare(self.db)
if not union in optPlans:
optPlans[union] = newJoin
self.addPlanCost(newJoin, newJoin.cost(estimated=True))
else:
formerCost = self.getPlanCost(optPlans[union])
if newJoin.cost(estimated=True) < formerCost:
optPlans[union] = newJoin
self.addPlanCost(newJoin, newJoin.cost(estimated=True))
newRoot = optPlans[frozenset(rels)]
return Plan(root=newRoot)
'''
def pickJoinOrder(self, plan):
self.combsTried = 0
self.plansProcessed = 0
self.rels = set(plan.relations())
#toBeProcessed = set()
self.tableScans = {}
for r in self.rels:
ts = TableScan(r, self.db.relationSchema(r))
ts.prepare(self.db)
self.tableScans[frozenset({r})] = ts
self.joinMap = {}
for (_, op) in plan.flatten():
if isinstance(op, Join):
relativeR = self.relativeRelations(self.rels, op)
for r in [frozenset({r}) for r in relativeR]:
if r in self.joinMap.keys():
self.joinMap[r].append((relativeR, op))
else:
self.joinMap[r] = [(relativeR, op)]
n = len(self.rels)
currBestPlan = None
formerBestPlan = None
formerRels = None
currRels = None
for i in range(2, n + 1):
currBestCost = float('inf')
if i == 2:
for left in [frozenset({left}) for left in self.rels]:
(newCost, newJoin,
newRels) = self.processJoin(self.tableScans[left], left)
if newCost < currBestCost:
currRels = newRels
currBestPlan = newJoin
currBestCost = newCost
else:
(newCost, newJoin,
newRels) = self.processJoin(formerBestPlan, formerRels)
if newCost < currBestCost:
currRels = newRels
currBestPlan = newJoin
currBestCost = newCost
formerBestPlan = currBestPlan
currBestPlan = None
formerRels = currRels
currRels = None
newRoot = formerBestPlan
return Plan(root=newRoot)
def pickJoinOrder(self, plan):
relations = plan.relations()
fieldDict = self.obtainFieldDict(plan)
(joinTablesDict, selectTablesDict) = self.getExprDicts(plan, fieldDict)
# makes dicts that maps a list of relations to exprs involving that list
# then in system R we will build opt(A,B) Join C using join exprs involving A,C and B,C
# and on top of it the select exprs that involve 2 tables A,C or B,C
isGroupBy = True if plan.root.operatorType() == "GroupBy" else False
outputSchema = plan.schema()
self.reportPlanCount = 0
worklist = []
for r in relations:
table = TableScan(r,self.db.relationSchema(r))
table.prepare(self.db)
if (r,) in selectTablesDict:
selectExprs = selectTablesDict[(r,)]
selectString = self.combineSelects(selectExprs)
select = Select(table,selectString)
select.prepare(self.db)
worklist.append(Plan(root=select))
else:
worklist.append(Plan(root=table))
while(len(worklist) > 1):
combos = itertools.combinations(worklist,2)
bestJoin = None
sourcePair = None
for pair in combos:
op1 = pair[0].root
op2 = pair[1].root
selectExpr = self.createExpression(pair[0].relations(), pair[1].relations(), selectTablesDict)
joinExpr = self.createExpression(pair[0].relations(), pair[1].relations(), joinTablesDict)
join1BnljOp = Join(op1, op2, expr=joinExpr, method="block-nested-loops" )
join2BnljOp = Join(op2, op1, expr=joinExpr, method="block-nested-loops" )
join1NljOp = Join(op1, op2, expr=joinExpr, method="nested-loops" )
join2NljOp = Join(op2, op1, expr=joinExpr, method="nested-loops" )
if selectExpr == "True":
full1BnljOp = join1BnljOp
full2BnljOp = join2BnljOp
full1NljOp = join1NljOp
full2NljOp = join2NljOp
else:
full1BnljOp = Select(join1BnljOp, selectExpr)
full2BnljOp = Select(join2BnljOp, selectExpr)
full1NljOp = Select(join1NljOp, selectExpr)
full2NljOp = Select(join2NljOp, selectExpr)
joinList = [full1BnljOp, full2BnljOp, full1NljOp, full2NljOp]
for j in joinList:
joinplan = Plan(root=j)
joinplan.prepare(self.db)
joinplan.sample(100)
if bestJoin == None or joinplan.cost(True) < bestJoin.cost(True):
bestJoin = joinplan
sourcePair = pair
self.reportPlanCount += 4
self.clearSampleFiles()
worklist.remove(sourcePair[0])
worklist.remove(sourcePair[1])
worklist.append(bestJoin)
# after System R algorithm
newPlan = worklist[0]
if isGroupBy:
newGroupBy = GroupBy(newPlan.root, groupSchema=plan.root.groupSchema, \
aggSchema=plan.root.aggSchema, groupExpr=plan.root.groupExpr, \
aggExprs=plan.root.aggExprs, \
groupHashFn=plan.root.groupHashFn)
newGroupBy.prepare(self.db)
newPlan = Plan(root=newGroupBy)
if set(outputSchema.schema()) != set(newPlan.schema().schema()):
projectDict = {}
for f, t in outputSchema.schema():
projectDict[f] = (f, t)
currRoot = newPlan.root
project = Project(currRoot, projectDict)
project.prepare(self.db)
newPlan = Plan(root=project)
return newPlan
def pickJoinOrder(self, plan):
relations = plan.relations()
fieldDict = self.obtainFieldDict(plan)
(joinTablesDict, selectTablesDict) = self.getExprDicts(plan, fieldDict)
# makes dicts that maps a list of relations to exprs involving that list
# then in system R we will build opt(A,B) Join C using join exprs involving A,C and B,C
# and on top of it the select exprs that involve 2 tables A,C or B,C
isGroupBy = True if plan.root.operatorType() == "GroupBy" else False
outputSchema = plan.schema()
self.reportPlanCount = 0
worklist = []
for r in relations:
table = TableScan(r, self.db.relationSchema(r))
table.prepare(self.db)
if (r, ) in selectTablesDict:
selectExprs = selectTablesDict[(r, )]
selectString = self.combineSelects(selectExprs)
select = Select(table, selectString)
select.prepare(self.db)
worklist.append(Plan(root=select))
else:
worklist.append(Plan(root=table))
while (len(worklist) > 1):
combos = itertools.combinations(worklist, 2)
bestJoin = None
sourcePair = None
for pair in combos:
op1 = pair[0].root
op2 = pair[1].root
selectExpr = self.createExpression(pair[0].relations(),
pair[1].relations(),
selectTablesDict)
joinExpr = self.createExpression(pair[0].relations(),
pair[1].relations(),
joinTablesDict)
join1BnljOp = Join(op1,
op2,
expr=joinExpr,
method="block-nested-loops")
join2BnljOp = Join(op2,
op1,
expr=joinExpr,
method="block-nested-loops")
join1NljOp = Join(op1,
op2,
expr=joinExpr,
method="nested-loops")
join2NljOp = Join(op2,
op1,
expr=joinExpr,
method="nested-loops")
if selectExpr == "True":
full1BnljOp = join1BnljOp
full2BnljOp = join2BnljOp
full1NljOp = join1NljOp
full2NljOp = join2NljOp
else:
full1BnljOp = Select(join1BnljOp, selectExpr)
full2BnljOp = Select(join2BnljOp, selectExpr)
full1NljOp = Select(join1NljOp, selectExpr)
full2NljOp = Select(join2NljOp, selectExpr)
joinList = [full1BnljOp, full2BnljOp, full1NljOp, full2NljOp]
for j in joinList:
joinplan = Plan(root=j)
joinplan.prepare(self.db)
joinplan.sample(100)
if bestJoin == None or joinplan.cost(True) < bestJoin.cost(
True):
bestJoin = joinplan
sourcePair = pair
self.reportPlanCount += 4
self.clearSampleFiles()
worklist.remove(sourcePair[0])
worklist.remove(sourcePair[1])
worklist.append(bestJoin)
# after System R algorithm
newPlan = worklist[0]
if isGroupBy:
newGroupBy = GroupBy(newPlan.root, groupSchema=plan.root.groupSchema, \
aggSchema=plan.root.aggSchema, groupExpr=plan.root.groupExpr, \
aggExprs=plan.root.aggExprs, \
groupHashFn=plan.root.groupHashFn)
newGroupBy.prepare(self.db)
newPlan = Plan(root=newGroupBy)
if set(outputSchema.schema()) != set(newPlan.schema().schema()):
projectDict = {}
for f, t in outputSchema.schema():
projectDict[f] = (f, t)
currRoot = newPlan.root
project = Project(currRoot, projectDict)
project.prepare(self.db)
newPlan = Plan(root=project)
return newPlan