I'm trying to connect my local PostgreSQL database to ArcMap 10.1 but for some reason I'm unable to connect to the server. Any ideas of what might be causing the issue. For the instance option in ArcMap I'm using the name of my server which is PostgreSQL 9.3 but i get "the unable to connect to data server" error. I have also tried localhost:5432 but i get the same error. Attached there is a pic showing the error the inputs and PostgreSQL server properties. Thanks for the help
Have you looked at Setting up a connection to PostgreSQL, specifically step #5 (you said you already have the client files):
Alter the PostgreSQL pg_hba.conf file on the database server to accept client connections. See the PostgreSQL documentation for information on altering the pg_hba.conf file.
I have an instance of PostgreSQL 9.3 that works with ArcGIS 10.2, but step 5 is a must. Even with the client files, ArcGIS still connects via tcp/ip (which is disabled by default).
Have you installed the client files for PostgreSQL in the ArcGIS /bin/ folder?
I had a very similar problem that I fixed by copying libeay32.dll, libiconv-2.dll, libintl-8.dll, libpq.dll, and ssleay32.dll from the PostgreSQL folder and put it into the ArcGIS10.1 \Bin\ folder.
Are you running PostgreSQL locally or is the server somewhere else?
Also try using just localhost in the instance box, that's what works for me.