python 两个数据库postgresql对比

这篇文章主要介绍了python 两个数据库postgresql对比,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

比较两个postgresql数据库，原理 比较数据库中各表的大小

1. 数据库查询语句

2. python字典比较

import psycopg2
import sys

class PdbModel:
  def __init__(self, host, dbname, username='postgres', password='postgres', port='5432'):
    self.host = host
    self.dbname = dbname
    self.username = username
    self.password = password
    self.port = port

    self.conn = None
    self.cursor = None
    self.init_db()

  def init_db(self):
    try:
      self.conn = psycopg2.connect(database=self.dbname, user=self.username, password=self.password,
                     host=self.host,
                     port="5432")
      self.cursor = self.conn.cursor()

    except Exception, e:
      error_out_print("Error: connection to db %s : %s failed. check need" % (self.host, self.dbname))
      print e
      sys.exit(-1)

  def execute_sql(self, sql, is_exist=True):
    """
      execute sql and return rows
    :param sql:
    :return:
      results of execute sql
    """
    try:
      standout_print('command sql : %s' % sql)
      self.cursor.execute(sql)
      rows = self.cursor.fetchall()
      return rows

    except Exception, e:
      self.conn.rollback()
      error_out_print("Failed: failed execute sql [%s]" % sql)
      error_out_print(e)
      if is_exist:
        self.close()
        sys.exit(-1)
      else:
        return None

  def get_tables_size(self):
    """
    select table_schema || '.' || table_name as table_full_name , pg_size_pretty(pg_total_relation_size('"'||table_schema||'"."'||table_name||'"')) as size
from information_schema.tables
order by pg_total_relation_size('"'||table_schema||'"."'||table_name||'"') DESC

    :return:
    """
    standout_print("get the size of tables in db [%s]." % self.dbname)
    sql = """
    select table_schema || '.' || table_name as table_full_name , pg_size_pretty(pg_total_relation_size('"'||table_schema||'"."'||table_name||'"')) as size
from information_schema.tables
order by pg_total_relation_size('"'||table_schema||'"."'||table_name||'"') DESC
    """
    rows = self.execute_sql(sql)
    table_size_dic = {}
    for row in rows:
      table_name = row[0]
      table_size = row[1]
      table_size_dic[table_name] = table_size
    return table_size_dic

def standout_print(info):
  sys.stdout.write("Info: %s " % info)
  sys.stdout.flush()

def error_out_print(info):
  sys.stderr.write("Error: %s " % info)
  sys.stderr.flush()

if __name__ == '__main__':
  db1 = ''
  db2 = ''
  host = "172.16.101.92"
  db_model1 = PdbModel(host, db1)
  db_model2 = PdbModel(host, db2)
  table_size_dic1 = db_model1.get_tables_size()
  table_size_dic2 = db_model2.get_tables_size()
  import pprint

  # pprint.pprint(table_size_dic1)
  # pprint.pprint(table_size_dic2)
  print cmp(table_size_dic1, table_size_dic2)
  is_equal = cmp(table_size_dic1, table_size_dic2)
  different_table_size_dic = {}
  if is_equal == 0:
    print "these tables in two database are same."
  else:
    keys1 = table_size_dic1.keys()
    keys2 = table_size_dic2.keys()

    for key in keys1:
      value1 = table_size_dic1.get(key)
      value2 = table_size_dic2.get(key)
      if cmp(value1, value2) != 0:
        different_table_size_dic[key] = (value1,value2)

  pprint.pprint(different_table_size_dic)

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