Re: psql on Mac

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От	Ozan Kahramanogullari
Тема	Re: psql on Mac
Дата	23 октября 2018 г. 18:08:58
Msg-id	CAPiqqL=KxV9xE9U_9MGp7_DmdYKCcfMe0UFHN2j94Y68k_2cdA@mail.gmail.com обсуждение исходный текст
Ответы	Re: psql on Mac (Andrej <andrej.groups@gmail.com>)
Список	pgsql-novice

Дерево обсуждения

Thanks, Jeff, for the explanation below. As you have pointed, I am moving the discussion to the novice list.

Logging in as "postgres" works by using "-U". However, few other things are not clear; I apologise for the long message...

If I want to run the "psql" for any user, for example, to create a database for the default user "ozan", this does not work.

Now, I have added another line to my file "ph_hba.conf". The first three lines of this file look as follows (although I am not completely sure about the semantics this creates... My intuition is that everything should be accessible to everyone locally, but almost nothing actually is).

local all all trust

local postgres postgres trust

local all postgres trust

XXX:src3 ozan$ psql -U ozan

Password for user ozan:

psql: FATAL: password authentication failed for user "ozan"

XXX:src3 ozan$ psql lecture

Password:

psql: FATAL: password authentication failed for user "ozan"

XXX:src3 ozan$ psql -U postgres lecture

psql: FATAL: database "lecture" does not exist

This is on a Mac. The only thing that works is the following, which is fine for messing around with sql commands:

psql -U postgres

Now, to combine my exercise with python, I am setting an environment variable as follows:

export DATABASE_URL="postgres://localhost:5432/lecture"

I am aware that I have NOT created a database called lecture, but this was not possible as well. However, I have created some database, and if I list it using the "-l" switch, I get the following.

XXX:src3 ozan$ psql -U postgres -l

List of databases

-----------+----------+----------+---------+-------+-----------------------

postgres | postgres | UTF8 | C | C |

template0 | postgres | UTF8 | C | C | =c/postgres +

template1 | postgres | UTF8 | C | C | =c/postgres +

(3 rows)

If I run the simple python code below, I get the messy error message at the bottom with no simple explanation.

I was convinced that I followed the instructions available out there, though there must be some setup stuff that I must have missed.

Can you please let me know what is missing? To be more concrete, my questions are the following:

1) What should I do to run the following command smoothly.

XXX:src3 ozan$ psql lecture

2) How can I make my python code run without any errors?

3) What is the semantics of the "ph_hba.conf" lines I have inserted?

4) Is there any documentation that explains all this for a novice who wants to have a gentle introduction? (I have collected bits and pieces of information from stackoverflow and other places, but it would be nice to have everything provided in a compact manner, so that one can have a smooth start.)

Best regards,

Ozan

#############

import os

from sqlalchemy import create_engine

from sqlalchemy.orm import scoped_session, sessionmaker

engine = create_engine(os.getenv("DATABASE_URL"))

db = scoped_session(sessionmaker(bind=engine))

def main():

flights = db.execute("SELECT origin, destination, duration FROM flights").fetchall()

for flight in flights:

print(f"{flight.origin} to {flight.destination}, {flight.duration} minutes.")

if __name__ == "__main__":

main()

############

XXX:src3 ozan$ python list.py

Traceback (most recent call last):

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2158, in _wrap_pool_connect

return fn()

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 403, in connect

return _ConnectionFairy._checkout(self)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 791, in _checkout

fairy = _ConnectionRecord.checkout(pool)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 532, in checkout

rec = pool._do_get()

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 1196, in _do_get

self._dec_overflow()

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__

compat.reraise(exc_type, exc_value, exc_tb)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 249, in reraise

raise value

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 1193, in _do_get

return self._create_connection()

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 350, in _create_connection

return _ConnectionRecord(self)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 477, in __init__

self.__connect(first_connect_check=True)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/pool.py", line 674, in __connect

connection = pool._invoke_creator(self)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/engine/strategies.py", line 106, in connect

return dialect.connect(*cargs, **cparams)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 412, in connect

return self.dbapi.connect(*cargs, **cparams)

File "/anaconda3/lib/python3.7/site-packages/psycopg2/__init__.py", line 130, in connect

conn = _connect(dsn, connection_factory=connection_factory, **kwasync)

psycopg2.OperationalError: fe_sendauth: no password supplied

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

File "list.py", line 17, in <module>

main()

File "list.py", line 12, in main

flights = db.execute("SELECT origin, destination, duration FROM flights").fetchall()

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/orm/scoping.py", line 153, in do

return getattr(self.registry(), name)(*args, **kwargs)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 1176, in execute

bind, close_with_result=True).execute(clause, params or {})

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 1040, in _connection_for_bind

engine, execution_options)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/orm/session.py", line 409, in _connection_for_bind

conn = bind.contextual_connect()

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2123, in contextual_connect

self._wrap_pool_connect(self.pool.connect, None),

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2162, in _wrap_pool_connect

e, dialect, self)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1476, in _handle_dbapi_exception_noconnection

exc_info

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 265, in raise_from_cause

reraise(type(exception), exception, tb=exc_tb, cause=cause)

File "/anaconda3/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 248, in reraise

raise value.with_traceback(tb)