LabVIEW with PostgreSQL password authentication

[lisam88]

I am trying to connect a PostgreSQL database (ver 9.6) with LabVIEW (2016) on Windows 10.

I followed the following tutorial:

https://decibel.ni.com/content/docs/DOC-30308

Without access to a cRIO, I have followed the steps to create the database, table and block diagram. Please see block diagram attached.The system exec.vi calls the psql.exe with SELECT command using database "lisam" and database user "postgres".

When I execute the same code I am asked for the password for user postgres. When I type in the password, the box closes and reopens. This continues in a loop until I press abort. I get no errors and when I write the same script into the cmd - the password is accepted and the table is displayed, see attachment.

PROBLEM:

• Password request from the psql.exe file when executing LabVIEW code
• Type password, psql.exe closes and opens again
• SELECT query works without while loop (password accepted once) but insert and clear does not without the loop condition

What I've tried...

1. Created a pgpass.conf file in a postgresql folder in %AppData% in the following format:- hostname:port:database:username:password.

Host name as localhost '127.0.0.1' - password still requested.

    127.0.0.1:5432:lisam:postgres:password

Host name as 'localhost' - psql.exe flashes continously and LabVIEW crashes. localhost:5432:database:username:password

Host name as database client address '::1' - password loop with the psql.exe.

    ::1:5432:database:username:password

Host name to '*' -

    *:5432:lisam:postgres:password

Able to:

• Access the database through the cmd WITHOUT password

  C:/Program Files/PostgreSQL/9.6/bin/psql -c "SELECT * FROM demo1" lisam postgres

Problems:

• Execution in Labview - psql.exe flashes continuously and the program crashes.
• Accessing database through psql.exe directly - password requested and ERROR received
  "psql: FATAL: password authentication failed for user C:\Program Files"

2.Changed the authentication method in pg_hba.conf to trust for:

• localhost (127.0.0.1)- a password is still requested.

• 127.0.0.1 AND ::1 - Can access the database on psql without a password, but the psql.exe LabVIEW completely crashes.

  1. I tried adding the host and port to the code

     C:/Program Files/PostgreSQL/9.6/bin/psql -c "%s" -h 127.0.0.1 -p 5432 lisam postgres

And the psql.exe flashes continously and won't abort.

1. The password is called at the system exec VI in the cmd. Tried concatenating the password (as a control) with space constant to the command line string inbetween the format into string and the system exec VI. But the password is given before it is called.

In summary I am able to use .pgpass.conf to authenticate the password when using the cmd, but not in LabVIEW. Does anyone know a way around this? Or another way to define the password at the system exec VI?

Your help is greatly needed.

Lisa

---

Info:

• database name: lisam
• database user: postgres

IPv4 local connections-

    host all all 127.0.0.1/32 md5

IPv6 local connections-

    host all all ::1/128 md5

    DB:lisam Client Address ::1    psql Client address 127.0.0.1

[ametcalf_css]

Hello Lisa,

Have you considered using the database connectivity toolkit?

http://www.ni.com/pdf/labview/us/database_connectivity_toolkit.pdf

Here also is a link to a forum page which talks through using postgreSQL with LabVIEW. I'm not a database expert, but I believe you should be able to interact with the database using ODBC drivers.

Best wishes,

Adam.

[lisam88]

Hi Adam,

Many thanks for your suggestion. I am currently testing a trial of the DB Connectivity Toolkit, but more for explorative purposes as the toolkit requires further licencing and costs (£££).

I managed to configure the postgres .pgpass file to automatically submit the password. This worked after placing the code in a sequence structure to give the system exec time to locate the password. So the code works now. I am now looking into making the process more efficient through connection pooling to keep the connection open. I've heard this can be done using ODBC drivers but I'm hoping I can do this without the Connectivity Toolkit to save money.

Do you have any knowledge with connection pooling?

Thanks again.

Lisa