python+postgreSql

def getopenconnection(user=‘postgres‘, password=‘1234‘, dbname=‘dds_assgn1‘):
    return psycopg2.connect("dbname=‘" + dbname + "‘ user=‘" + user + "‘ host=‘localhost‘ password=‘" + password + "‘")


def loadratings(ratingstablename, ratingsfilepath, openconnection):
    cur = openconnection.cursor()
    cur.execute(‘Drop Table if exists Ratings; CREATE TABLE Ratings(UserID int NOT NULL, movieid int NOT NULL, Rating double precision, CONSTRAINT key PRIMARY KEY (UserID, movieid));‘)
    with open(ratingsfilepath, "r") as ins:
        for line in ins:
            array=line.split("::")
            cur.execute(‘INSERT INTO Ratings VALUES ({0},{1},{2})‘ .format(array[0],array[1],array[2]))
    openconnection.commit()
    cur.close()
    pass

def rangepartition(ratingstablename, numberofpartitions, openconnection):
    cur=openconnection.cursor()
    #part=(5-0.5)/numberofpartitions
    part=5/numberofpartitions
    for i in range(0,numberofpartitions):
        str=‘Drop Table if exists range_part{0};CREATE TABLE range_part{0}(UserID int NOT NULL, movieid int NOT NULL, Rating double precision, PRIMARY KEY (UserID, movieid));‘.format(i)
        print(str)
        cur.execute(str)
    cur.execute(‘select * from {0}‘.format(ratingstablename))
    result=cur.fetchall()
    for row in result:
        #i=(row[2]-0.01-0.5)/part
        i=(row[2]-0.01)/part
        i=int (i)
        cur.execute(‘INSERT INTO range_part{3} VALUES ({0},{1},{2})‘ .format(row[0],row[1],row[2],i))
    cur.execute(‘Drop Table if exists hrange_record;CREATE TABLE hrange_record(n text NOT NULL,part text NOT NULL);‘)
    cur.execute(‘INSERT INTO hrange_record VALUES ({0},{1})‘ .format(numberofpartitions,part))
    openconnection.commit()
    cur.close()
    pass