Psycopg2.databaseerror: error with status pgres_tuples_ok and no message from the libpq

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pgres_tuples_ok Error in psycopg2

The psycopg2 library is a popular PostgreSQL adapter for the Python programming language. It allows Python programs to interact with a PostgreSQL database.

The specific error you encountered, psycopg2.DatabaseError: error with status pgres_tuples_ok and no message from the libpq, typically occurs when there is an issue with the data returned from the PostgreSQL server.

To better understand this error, let’s dive into the possible causes and how to troubleshoot it.

Possible Causes

  • Incorrect SQL query or syntax error
  • Null values or unexpected data types returned
  • Incorrect usage of psycopg2 library

Troubleshooting

Here are some steps you can take to troubleshoot and resolve the pgres_tuples_ok error:

  1. Check Your SQL Query: Verify that your SQL query is correct and does not contain any syntax error. Make sure you are using the correct table and column names, and the query is properly structured.
  2. Inspect Returned Data: If your query is syntactically correct, but the error still persists, examine the data returned from the PostgreSQL server. Ensure that the values do not contain unexpected null values or incompatible data types.
  3. Handle Errors and Exceptions: Wrap your psycopg2 queries in appropriate error handling and exception blocks. This will allow you to catch any specific errors, such as DataError or ProgrammingError, and provide more detailed error messages.
  4. Update psycopg2 Version: Ensure that you are using the latest version of psycopg2. Some issues may be resolved by updating to the newest release.

Example

Here’s an example code snippet that illustrates how to catch the pgres_tuples_ok error and display a detailed error message: 


import psycopg2

try:
    conn = psycopg2.connect(database="mydb", user="myuser", password="mypassword", host="localhost", port="5432")
    cur = conn.cursor()
    cur.execute("SELECT * FROM nonexistent_table")
except psycopg2.DatabaseError as error:
    print("Error with status:", error.pgcode, "Message:", error.pgerror)

In this example, if the table “nonexistent_table” does not exist in the PostgreSQL database, the pgres_tuples_ok error will be raised. The error code and message can then be extracted from the psycopg2.DatabaseError object and displayed.

Remember to modify the connection parameters (database, user, password, host, port) according to your PostgreSQL setup.

By following the troubleshooting steps and utilizing error handling, you can effectively address and resolve the pgres_tuples_ok error in psycopg2.

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