# Pt-online-schema-change

**URL:** <https://forums.percona.com/t/pt-online-schema-change/22401>\
**Category:** MySQL & MariaDB\
**Created:** [May 30, 2023, 9:34pm UTC](https://forums.percona.com/t/pt-online-schema-change/22401 "2023-05-30T21:34:47Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ChrisDK](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@ChrisDK](https://forums.percona.com/u/ChrisDK)\
**Post date:** [May 30, 2023, 9:34pm UTC](https://forums.percona.com/t/pt-online-schema-change/22401/1 "2023-05-30T21:34:47Z")

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Using pt-online-schema-change with option --max-load “Threads\_running=100”.

According to Percona documentation the process should pause when threads\_running is over the calculated threshold. However, my instance aborts.

Is this a known bug in pt-online-schema-change ?

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**Author:** ![kedarpercona](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/kedarpercona/32/809_2.png) [@kedarpercona](https://forums.percona.com/u/kedarpercona)\
**Post date:** [May 31, 2023, 3:59am UTC](https://forums.percona.com/t/pt-online-schema-change/22401/2 "2023-05-31T03:59:17Z")

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Hello Chris,

I think you’re missing [–critical-load option](https://docs.percona.com/percona-toolkit/pt-online-schema-change.html#cmdoption-pt-online-schema-change-critical-load).

The relevant section says

> –critical-load[¶](https://docs.percona.com/percona-toolkit/pt-online-schema-change.html#cmdoption-pt-online-schema-change-critical-load)
> 
> type: Array; **default: Threads\_running=50**
> 
> Examine SHOW GLOBAL STATUS after every chunk, and **abort if the load is too high**.

You might want to add --critical-load “Threads\_running=150”.

Thanks,  
K.

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<div class="post-metadata">

**Author:** ![ChrisDK](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@ChrisDK](https://forums.percona.com/u/ChrisDK)\
**Post date:** [May 31, 2023, 2:56pm UTC](https://forums.percona.com/t/pt-online-schema-change/22401/3 "2023-05-31T14:56:51Z")

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Thanks for the reply.

However, according to the docs you posted --critical-load will ‘abort’ the operation. I do not want to abort, I want the operation to pause so it will complete.

According to Percona’s docs --max-load will ‘pause’ the operation, but in my case it is aborting it.

I’m wondering if this is a bug in pt-online-schema-change or am I missing something?

Thanks.

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<div class="post-metadata">

**Author:** ![kedarpercona](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/kedarpercona/32/809_2.png) [@kedarpercona](https://forums.percona.com/u/kedarpercona)\
**Post date:** [May 31, 2023, 3:02pm UTC](https://forums.percona.com/t/pt-online-schema-change/22401/4 "2023-05-31T15:02:16Z")

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Hi Chris,

I wanted to highlight the default value for --critical-load (50) is lower than your --max-load (100). You will need to mention that.

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<div class="post-metadata">

**Author:** ![ChrisDK](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@ChrisDK](https://forums.percona.com/u/ChrisDK)\
**Post date:** [May 31, 2023, 6:18pm UTC](https://forums.percona.com/t/pt-online-schema-change/22401/5 "2023-05-31T18:18:41Z")

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Oh I understand. So I will have to increase critical to above my value for max. This makes sense!

Thanks for this. Will test on my end and hopefully close this out.