Simulating multi-user to operate PostgreSQL by Python？

Question

I want to compare my distributed database and postgresql. So I need to simulate multi-user SQL operations on postgresql using Python.

Can I use the mutliprocessing module？

here is my code

 # encoding=utf-8
import datetime
import multiprocessing
import psycopg2

def exe(cmd):
    conn = psycopg2.connect("dbname = test user = pj password = dbrgdbrg")
    cur = conn.cursor()
    try:
        sql = "SELECT id FROM test WHERE ST_MAKEENVELOPE(118,38,119,39,4326) && wkb_geometry;"
        cur.execute(sql)
        print cur.fetchone()
    except Exception, e:
        print e

if __name__ == "__main__":
    cmds=range(5)
    for cmd in  cmds:
        p = multiprocessing.Process(target=exe,args=(cmd,))
        p.start()
        p.join()

But I don't know if it is correct? What should I do if I wanted to create random parameter to my SQL statements?

harshil9968 · Accepted Answer · 2016-09-21 14:16:46Z

1

You can use the random function to generate random 'ST_MAKEENVELOPE` qualifiers this is assuming they belong to some range. And then use the random function to get 5 different ID's of ST_MAKEENVELOPE.

Another thing you can just use for cmd in range(5): instead of creating a list and then using it.

answered Sep 21, 2016 at 14:16

harshil9968

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2 Comments

user82538 Over a year ago

but when I running sql = "SELECT id from test where id < random.randint(0,10) " it is prompt psycopg2.ProgrammingError: schema "random" does not exist LINE 1: SELECT id from test where id < random.randint(0,10) ^

harshil9968 Over a year ago

sql = "SELECT id from test where id < " + str(random.randint(0,10))

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