Question 225171 in PostgreSQL Question posted in
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Issues connecting to postgresql using python on Mac

I am trying to connect to postgresql using the following code

import psycopg2

hostname = 'localhost'
database = 'demo'
username = 'postgres'
pwd = 'johndoe'
port_d= 5432
        
        
conn = psycopg2.connect(
            host=hostname,
            dbname=database,
            user = username,
            password=pwd,
            port = port_d)


conn.close()

I have installed psycopg2 using pip install psycopg2.

Somehow when I try establishing a connection I get this error.
Im not sure what I am doing wrong

Traceback (most recent call last):
  File "/Users/abiodunadeoye/KINGS-PLATFORM/Postgres/ETL/connect.py", line 1, in <module>
    import psycopg2
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/psycopg2/__init__.py", line 51, in <module>
    from psycopg2._psycopg import (                     # noqa
ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/psycopg2/_psycopg.cpython-37m-darwin.so, 0x0002): Library not loaded: @rpath/libpq.5.dylib
  Referenced from: <D5013EE3-2219-32DC-A518-A4DA08CF3918> /Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/psycopg2/_psycopg.cpython-37m-darwin.so
  Reason: tried: '/usr/local/lib/libpq.5.dylib' (no such file), '/usr/lib/libpq.5.dylib' (no such file, not in dyld cache)
Tags:

3

Answers


  1. 0

    If we’re just talking for local use, you want to use the standalone psycopg2-binary package:

    pip install psycopg2-binary

    Otherwise it will try to dynamically link libpq, which you apparently don’t have on your system. See the psycopg2 documentation for a discussion of the difference. If you want to use the non-standalone version you will need to install libpq and libssl with homebrew and symlink them to the appropriate locations that psycopg2 expects to find them.

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  2. 0

    Faced a similar issue on mac.

    This fixed it for me:
    sudo ln -s /opt/homebrew/opt/postgresql@14/lib/postgresql@14/libpq.5.dylib /usr/local/lib/libpq.5.dylib

    Basically, this creates a symbolic link for ‘libpq.5.dylib’ in ‘/usr/local/lib/’ directory. This link points to the original ‘libpq.5.dylib’ library file located in my PostgreSQL 14 installation through Homebrew.

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  3. 0

    A quick fix for this would be to install the psycopg2-binary standalone package which contains the necessary PostgreSQL client libraries. This would help with the library loading issues you are currently encountering.

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