# pt-query-digest what is \\$event-\>{Bytes} = length(\\$event-\>{arg}) mean?

**URL:** <https://forums.percona.com/t/pt-query-digest-what-is-event-bytes-length-event-arg-mean/7095>\
**Category:** Percona Toolkit\
**Created:** [July 3, 2019, 8:45am UTC](https://forums.percona.com/t/pt-query-digest-what-is-event-bytes-length-event-arg-mean/7095 "2019-07-03T08:45:36Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Fan](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/fan/32/40_2.png) [@Fan](https://forums.percona.com/u/Fan)\
**Post date:** [July 3, 2019, 8:45am UTC](https://forums.percona.com/t/pt-query-digest-what-is-event-bytes-length-event-arg-mean/7095/1 "2019-07-03T08:45:36Z")

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$event-\>{Bytes} = length($event-\>{arg})  
see this in anemometer  
what is this filter mean? can’t understand