How can I extract data with delimiter?

[yk010123]

I have a log entry with the current format: 

field=A_B

(delimited by underscore)

How can I extract this data into two different fields so that I can create a table 

field1	field2
A	B

[bowesmana · Accepted solution]

If your field is called 'field' then this

| rex field=field "(?<field1>[^_]*)_(?<field2>.*)"

will create new fields 'field1' and 'field2'