Vertica filters

Request filters are invoked when a request is received from a database client, before it is forwarded to the Vertica server. 

Response filters are invoked when a response is received from the Vertica server, before it is forwarded to the client. 

Filters are given the opportunity to look at the packet and do whatever they want with it: let it through, modify it, or reject it. Unless it's rejected, the packet is then forwarded to its destination.

Context

All filters define the following variables, which can be accessed from your JavaScript code:

• log : A Logger object to output messages to the logging system

• context : a container object described in the Vertica Contexts page

Request filters types

• JavaScript request filter : invoked for any request from clients

• Query filter: invoked for SQL queries, including (optionally) prepared statements

• Login filter: invoked when a login is attempted into the database.

• Request logging filter: can log any request packets to standard log or to a log file

Response filter types

• JavaScript response filter: can be invoked for any response from the database server.

• Result set filter: can be invoked for every row in a result set, whether from a SQL query or a stored procedure call.

• Response logging filter : can log any responses from the database server to a file or to standard out.