The error ('H000', '[H000] [ (50404) (SQLDriverConnect)') is a generic ODBC error that indicates the pyodbc connection attempt failed during the initial driver connection phase (SQLDriverConnect), specifically when using the configuration defined in your DSN (Data Source Name) or connection string.
The H000 SQLSTATE and the driver-specific error code (50404) often point to a fundamental problem with the connection string's format or parameters. Since isql works but pyodbc does not, the issue is likely how the connection details are being passed or interpreted by the Python environment.
Possible RCA:
1. Improper DSN Specification in pyodbc (Most Common): The isql tool implicitly knows how to look up the DSN defined in your odbc.ini file. pyodbc requires the connection string to be in a very specific format. If you pass the DSN name directly without the proper prefix, it can fail with this error.
2. Missing or Incorrect Connection Parameters: If you are using a full connection string instead of a DSN, a single missing or misspelled parameter (like HOST, PORT, Driver, or security mechanisms like AuthMech) will cause the driver to reject the connection immediately.
3. ODBC Driver Manager Conflict (Linux/macOS): On Linux/macOS, Impala uses a driver manager like UnixODBC or iODBC. If pyodbc is compiled against a different driver manager than the one isql uses, they might not be reading the same configuration files or environment variables (ODBCINI, LD_LIBRARY_PATH).
Resolution Steps:
1. Fix the pyodbc Connection String Format: Ensure you are explicitly telling pyodbc to use a DSN defined in your configuration files.
- If connecting using a DSN: Use format DSN=<Your_Impala_DSN_Name>.
conn = pyodbc.connect('DSN=MyImpalaDSNName')
- If connecting using a DSN-less connection string: Ensure all critical parameters are present and correctly formatted.
conn_str = (
'Driver={Cloudera ODBC Driver for Impala};'
'Host=<Impala_Host>;'
'Port=<Impala_Port>;'
'AuthMech=3;' # Example: 3 for Username/Password
'UID=<username>;'
'PWD=<password>'
)
conn = pyodbc.connect(conn_str)
2. Verify Security and Authentication Parameters: Since isql might be implicitly handling Kerberos or LDAP, ensure these are explicitly defined for pyodbc:
- If your cluster uses LDAP (User Name and Password), confirm the UID and PWD parameters are correctly placed and the AuthMech parameter is set to the correct value (often 3 or 5 depending on the driver version).
- If your cluster uses Kerberos, ensure the KrbRealm, KrbFQDN, and KrbServiceName parameters are correctly defined in your DSN or connection string.
3. Check Library Path (Linux/macOS): If you are using UnixODBC, ensure that the directory containing the ODBC driver manager libraries is included in the LD_LIBRARY_PATH environment variable. The Impala driver may need this path to load correctly, which pyodbc sometimes fails to handle automatically, while isql's setup might cover it.
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path/to/unixodbc/lib
