logstash/logstash — pull request #197 by wathrog (2012-09-05 12:20:44+00:00)
Title: [FEATURE] Alter filter plugin

Alter plugin gives some handy tool to manipulate fields:

1. _Conditional rewrite_:
Sets the value of a field to a specified one if the current value matches an expression

2. _Conditional rewrite other field_:
Sets the value of a field to a specified one if the current value of another field matches an expression

3. _Coalesce_:
Sets the value of a field to the first of its not null arguments