利用python為PostgreSQL的表自動添加分區(qū)

更新時間：2021年01月18日 09:44:44 作者：PostgreSQLChina

這篇文章主要介紹了利用python為PostgreSQL的表自動添加分區(qū)，文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值，需要的朋友們下面隨著小編來一起學習學習吧

PostgreSQL引進“分區(qū)”表特性，解放了之前采用“表繼承”+“觸發(fā)器”來實現(xiàn)分區(qū)表的繁瑣、低效。而添加分區(qū)，都是手動執(zhí)行SQL。

演示目的：利用python來為PostgreSQL的表自動添加分區(qū)。
python版本：python3+

pip3 install psycopg2

一、配置數(shù)據(jù)源

database.ini 文件：記錄數(shù)據(jù)庫連接參數(shù)

[adsas]
host=192.168.1.201
database=adsas
user=adsas
password=adsas123
port=5432

[test]
host=192.168.1.202
database=adsas
user=adsas
password=adsas123
port=5432

二、config 腳本

config.py 文件：下面的 config() 函數(shù)讀取 database.ini 文件并返回連接參數(shù)。config() 函數(shù)位于config.py文件中

#!/usr/bin/python3
from configparser import ConfigParser
 
def config(section ,filename='database.ini'):
  # create a parser
  parser = ConfigParser()
  # read config file
  parser.read(filename)
 
  # get section, default to postgresql
  db = {}
  if parser.has_section(section):
    params = parser.items(section)
    for param in params:
      db[param[0]] = param[1]
  else:
    raise Exception('Section {0} not found in the {1} file'.format(section, filename))
 
  return db

三、創(chuàng)建子表腳本

pg_add_partition_table.py 文件：其中 create_table函數(shù)是創(chuàng)建子表SQL。其中參數(shù)

參數(shù)名	含義
db	指向數(shù)據(jù)庫
table	主表
sub_table	正要新建的子表名
start_date	范圍分界開始值
end_date	范圍分界結(jié)束值

#!/usr/bin/python3

import psycopg2
from config import config

#example: create table tbl_game_android_step_log_2021_07 PARTITION OF tbl_game_android_step_log FOR VALUES FROM ('2021-07-01') TO ('2021-08-01');
def create_table(db, table, sub_table, start_date, end_date):
  """ create subtable in the PostgreSQL database"""
  command = "create table {0} PARTITION OF {1} FOR VALUES FROM ('{2[0]}') TO ('{2[1]}');".format(sub_table, table, (start_date, end_date)) 
  conn = None
  try:
    # read the connection parameters
    params = config(section = db)
    # connect to the PostgreSQL server
    conn = psycopg2.connect(**params)
    cur = conn.cursor()
    # create table one by one
    cur.execute(command)
    # close communication with the PostgreSQL database server
    cur.close()
    # commit the changes
    conn.commit()
  except (Exception, psycopg2.DatabaseError) as error:
    print(error)
  finally:
    if conn is not None:
      conn.close()

四、執(zhí)行文件main.py

main.py：主文件；通過執(zhí)行main生成分區(qū)表。

示例：

#!/usr/bin/python3
import datetime
from datetime import date
from dateutil.relativedelta import *
from pg_add_partition_table import create_table

#Get the 1st day of the next month
def get_next_month_first_day(d):
  return date(d.year + (d.month == 12), d.month == 12 or d.month + 1 , 1)
  
def create_sub_table(db, table):
  # Get current date
  d1 = date.today()
  # Get next month's date
  d2 = d1 + relativedelta(months=+1)
  # Get the 1st day of the next month;As the starting value of the partitioned table
  start_date = get_next_month_first_day(d1)
  # Gets the 1st of the next two months as the end value of the partitioned table
  end_date = get_next_month_first_day(d2)
  # get sub table name
  getmonth = datetime.datetime.strftime(d2, '%Y_%m')
  sub_table = table + '_' + getmonth
  create_table(db, table, sub_table, start_date, end_date)
 
if __name__ == '__main__':
  create_sub_table('test', 'tbl_game_android_step_log');

上面示例單獨為表tbl_game_android_step_log；創(chuàng)建分區(qū)；若多個表；用for語句處理

# 多表操作

  for table in ['tbl_game_android_step_log', 'tbl_game_android_game_log','tbl_game_android_pay_log']:
    create_sub_table('test', table);
演示之前：
adsas=> select * from pg_partition_tree('tbl_game_android_step_log');
        relid        |    parentrelid    | isleaf | level 
-----------------------------------+---------------------------+--------+-------
 tbl_game_android_step_log     |              | f   |   0
 tbl_game_android_step_log_2020_12 | tbl_game_android_step_log | t   |   1
(2 rows)

演示之后：

adsas=> select * from pg_partition_tree('tbl_game_android_step_log');
        relid        |    parentrelid    | isleaf | level 
-----------------------------------+---------------------------+--------+-------
 tbl_game_android_step_log     |              | f   |   0
 tbl_game_android_step_log_2020_12 | tbl_game_android_step_log | t   |   1
 tbl_game_android_step_log_2021_01 | tbl_game_android_step_log | t   |   1

Partition key: RANGE (visit_time)
Partitions: tbl_game_android_step_log_2020_12 FOR VALUES FROM ('2020-12-01 00:00:00') TO ('2021-01-01 00:00:00'),
      tbl_game_android_step_log_2021_01 FOR VALUES FROM ('2021-01-01 00:00:00') TO ('2021-02-01 00:00:00')

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