Proxy Users and Delegation Tokens
An alternative to granting HDFS access to individual Vertica users is to use delegation tokens, either directly or with a proxy user. In this configuration, Vertica accesses HDFS on behalf of some other (Hadoop) user. The Hadoop users need not be Vertica users at all.
In Vertica, you can either specify the name of the Hadoop user to act on behalf of (doAs), or you can directly use a Kerberos delegation token that you obtain from HDFS (Bring Your Own Delegation Token). In the doAs case, Vertica obtains a delegation token for that user, so both approaches ultimately use delegation tokens to access files in HDFS.
Use the HadoopImpersonationConfig session parameter to specify a user or delegation token to use for HDFS access. Each session can use a different user and can use either doAs or a delegation token. The value of HadoopImpersonationConfig is a set of JSON objects. See HadoopImpersonationConfig Format for details.
When using delegation tokens of either type (more specifically, when HadoopImpersonationConfig is set), Vertica falls back to WebHDFS to access data. This fallback is automatic; continue to use the
hdfs URL scheme when using delegation tokens.