Replace null with string

[Mario Lassnig]

Hello,

I'm having a lot of null entries in my data. Due to later processing it would be 
very helpful if I could set a default value for null to be the string "other". I 
couldn't find a way to do this (version 0.8.1-cdh3u4)

Also, I have some variables in my GENERATE statements that can potentially 
return null, and I would need something similar to the SQL DECODE function to 
get the "other" string instead of null.

Example:

tmp = FOREACH dump GENERATE site, REGEX_EXTRACT(name, '^(?:([^.]+)\\.?){1}', 1) 
AS project, ((ami MATCHES '.*datatype.*') ? REGEX_EXTRACT(name, 
'^(?:([^.]+)\\.?){5}', 1) : 'other') AS datatype, ami, duid, nbfiles, length, 
rnbfiles, rlength, name;

Here: 'site' and 'datatype' could return an empty string (which is valid) and is 
interpreted as null, but should be "other" instead.

Thanks a lot,
Mario