I'm using Pentaho 7.1 and I have some questions

1) As I know, AuditLog file always being appended. Can I split Pentaho 7.1 AuditLog by max filesize in pentaho.xml?
2) (audit) log file better or log SQL better? If I use SQL log and it (Pentaho) insert too much data, introduce significant memory overhead, what can i do? how can I replace (in case of turn off)

Thank in advantage