# Understanding --limit in percona toolkit pt-query-digest
**URL:** https://forums.percona.com/t/understanding-limit-in-percona-toolkit-pt-query-digest/32647
**Category:** Percona Toolkit
**Tags:** mysql
**Created:** [August 28, 2024, 7:48am UTC](https://forums.percona.com/t/understanding-limit-in-percona-toolkit-pt-query-digest/32647 "2024-08-28T07:48:40Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Idan\_Ahal](https://forums.percona.com/u/Idan_Ahal)
#### Post date: [August 28, 2024, 7:48am UTC](https://forums.percona.com/t/understanding-limit-in-percona-toolkit-pt-query-digest/32647/1 "2024-08-28T07:48:40Z")
I read all the docs and didn’t totally understand how --limit works.
Why would I want to use the percentage option and not analyze all?
Also, if I group by user, Will it give me a different result? because the limit runs before the filter?
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### Author:  [@Idan\_Ahal](https://forums.percona.com/u/Idan_Ahal)
#### Post date: [August 28, 2024, 7:59am UTC](https://forums.percona.com/t/understanding-limit-in-percona-toolkit-pt-query-digest/32647/2 "2024-08-28T07:59:02Z")
OK I understand it now. I thought it filters the queries before aggregation but it’s after.