如何为PostgreSQL的表自动添加分区
PostgreSQL 引进“分区”表特性，解放了之前采用“表继承”+ “触发器”来实现分区表的繁琐、低效。而添加分区，都是手动执行 SQL。
演示目的：利用 python 来为 PostgreSQL 的表自动添加分区。
python版本： python3+
pip3 install psycopg2
一、配置数据源
database.ini 文件：记录数据库连接参数
[adsas]host=192.168.1.201database=adsasuser=adsaspassword=adsas123port=5432[test]host=192.168.1.202database=adsasuser=adsaspassword=adsas123port=5432
二、config 脚本
config.py 文件：下面的config() 函数读取database.ini文件并返回连接参数。config() 函数位于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、创建子表脚本
pg_add_partition_table.py 文件：其中 create_table函数是创建子表SQL。其中参数
| 参数名 | 含义 |
|---|---|
| db | 指向数据库 |
| table | 主表 |
| sub_table | 正要新建的子表名 |
| start_date | 范围分界开始值 |
| end_date | 范围分界结束值 |
#!/usr/bin/python3import psycopg2from 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、执行文件main.py
main.py：主文件；通过执行main生成分区表。
示例：
#!/usr/bin/python3import datetimefrom datetime import datefrom dateutil.relativedelta import *from pg_add_partition_table import create_table# Get the 1st day of the next monthdef 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');上面示例单独为表tbl_game_android_step_log；创建分区；若多个表；用for语句处理
# 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 | 1Partition 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')五、加入定时任务
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