def main(cls, args):
# db = SimpleDB("plannertest1")
fm = FileMgr(File("plannertest1"), 400)
lm = LogMgr(fm, "simpledb.log")
bm = BufferMgr(fm, lm, 8)
tx = Transaction(fm, lm, bm)
isnew = fm.isNew()
mdm = MetadataMgr(isnew, tx)
qp = BasicQueryPlanner(mdm)
up = BasicUpdatePlanner(mdm)
planner = Planner(qp, up)
cmd = "create table T1(A int, B varchar(9))"
planner.executeUpdate(cmd, tx)
n = 200
print("Inserting " + str(n) + " random records.")
for i in range(n):
a = random.randint(0, 50)
b = "rec" + str(a)
cmd = "insert into T1(A,B) values(" + str(a) + ", '" + b + "')"
planner.executeUpdate(cmd, tx)
qry = "select B from T1 where A=10"
p = planner.createQueryPlan(qry, tx)
s = p.open()
while s.next:
print(s.getString("b"))
s.close()
tx.commit()
def main(cls, args):
# db = SimpleDB("studentdb")
fm = FileMgr(File("plannertest2"), 400)
lm = LogMgr(fm, "simpledb.log")
bm = BufferMgr(fm, lm, 8)
tx = Transaction(fm, lm, bm)
isnew = fm.isNew()
mdm = MetadataMgr(isnew, tx)
qp = BasicQueryPlanner(mdm)
up = BasicUpdatePlanner(mdm)
planner = Planner(qp, up)
# part 1: Process a query
qry = "select sname, gradyear from student"
p = planner.createQueryPlan(qry, tx)
s = p.open()
while s.next:
print(s.getString("sname") + " " + str(s.getInt("gradyear")))
s.close()
# part 2: Process an update command
cmd = "delete from STUDENT where MajorId = 30"
num = planner.executeUpdate(cmd, tx)
print(str(num) + " students were deleted")
tx.commit()
class SimpleDB(object):
BLOCK_SIZE = 400
BUFFER_SIZE = 8
LOG_FILE = "simpledb.log"
def __init__(self, *args):
if len(args) == 3:
#
# * A constructor useful for debugging.
# * @param dirname the name of the database directory
# * @param blocksize the block size
# * @param buffsize the number of buffers
#
dirname, blocksize, buffsize = args
dbDirectory = File(dirname)
self.fm = FileMgr(dbDirectory, blocksize)
self.lm = LogMgr(self.fm, SimpleDB.LOG_FILE)
self.bm = BufferMgr(self.fm, self.lm, buffsize)
else:
#
# * A simpler constructor for most situations. Unlike the
# * 3-arg constructor, it also initializes the metadata tables.
# * @param dirname the name of the database directory
#
dirname = args[0]
self.__init__(dirname, self.BLOCK_SIZE, self.BUFFER_SIZE)
tx = self.newTx()
isnew = self.fm.isNew()
if isnew:
print("creating new database")
else:
print("recovering existing database")
tx.recover()
self.mdm = MetadataMgr(isnew, tx)
qp = BasicQueryPlanner(self.mdm)
up = BasicUpdatePlanner(self.mdm)
# QueryPlanner qp = new HeuristicQueryPlanner(mdm);
# UpdatePlanner up = new IndexUpdatePlanner(mdm);
self._planner = Planner(qp, up)
tx.commit()
#
# * A convenient way for clients to create transactions
# * and access the metadata.
#
def newTx(self):
return Transaction(self.fm, self.lm, self.bm)
def mdMgr(self):
return self.mdm
def planner(self):
return self._planner
# These methods aid in debugging
def fileMgr(self):
return self.fm
def logMgr(self):
return self.lm
def bufferMgr(self):
return self.bm