# pt-query-digest $event-\>{bytes} \>= 1\_048\_576 why "\_" in there?

**URL:** <https://forums.percona.com/t/pt-query-digest-event-bytes-1-048-576-why-in-there/7113>\
**Category:** Percona Toolkit\
**Created:** [July 10, 2019, 7:15pm UTC](https://forums.percona.com/t/pt-query-digest-event-bytes-1-048-576-why-in-there/7113 "2019-07-10T19:15:56Z")\
**Posts on this page:** 2\
**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 10, 2019, 7:15pm UTC](https://forums.percona.com/t/pt-query-digest-event-bytes-1-048-576-why-in-there/7113/1 "2019-07-10T19:15:56Z")

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in the doc  
Query is 1 MB or larger  
$event-\>{bytes} \>= 1\_048\_576  
why not $event-\>{bytes} \>= 1048576? what is ‘\_’ mean?

Is 1M the size of sql text? what is the calculation method?  
select length(“select \* from xx where id=1”) ?

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**Author:** ![carlos.salguero](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/carlos.salguero/32/20_2.png) [@carlos.salguero](https://forums.percona.com/u/carlos.salguero)\
**Post date:** [July 11, 2019, 6:11am UTC](https://forums.percona.com/t/pt-query-digest-event-bytes-1-048-576-why-in-there/7113/2 "2019-07-11T06:11:31Z")

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Hello,

In Percona Server, the slow log contains a line with the number of bytes sent like:

```auto
# Bytes_sent: 41

```

That can be used in filters as

```auto
$event->{bytes}

```

Regarding the underscore in numbers: [URL][https://www.perltutorial.org/perl-numbers/[/URL]](https://www.perltutorial.org/perl-numbers/%5B/URL%5D)

Regards