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https://issues.apache.org/jira/browse/KAFKA-7137?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Brett Rann updated KAFKA-7137:
------------------------------
Description:
Just spent some time wrapping my head around the inner workings of compaction
and tombstoning, with a view to providing guarantees for deleting previous
values of tombstoned keys from kafka within a desired time.
There's a couple of good posts that touch on this:
https://www.confluent.io/blog/handling-gdpr-log-forget/
http://www.shayne.me/blog/2015/2015-06-25-everything-about-kafka-part-2/
Basically, log.cleaner.min.cleanable.ratio or min.cleanable.dirty.ratio is
hijacked to force aggressive compaction (by setting it to 0, or 0.000000001
depending on what you read), and along with segment.ms can provide timing
guarantees that a tombstone will result in any other values for the key will be
deleted within a desired time.
But that sacrifices the utility of min.cleanable.dirty.ratio (and to a lesser
extent, control over segment sizes). On any duplicate key and a new segment
roll it will run compaction, when otherwise it might be preferrable to allow a
more generous dirty.ratio in the case of plain old duplicates.
It would be useful to have control over triggering a compaction without losing
the utility of the dirty.ratio setting.
The pure need here is to specify a minimum time for the log cleaner to run (or
a maximum time where it doesn't run!) on a topic that has keys replaced by a
tombstone message that are past the minimum retention times provided by
min.compaction.lag.ms
Something like a log.cleaner.max.delay.ms, and an API to trigger compaction,
with some nuances to be fleshed out.
Does this make sense, and sound like it's worth a KIP? I'd be happy to write
something up.
In the mean time, this can be worked around with some duct tape:
* make sure any values you want deleted by a tombstone have passed min
retention configs
* set global log.cleaner.io.max.bytes.per.second to what you want for the
compaction task
* set topic min.cleanable.dirty.ratio=0 for the topic
* set a small segment.ms
* wait for a new segment to roll (ms + a message coming in) and wait for
compaction to kick in. GDPR met!
* undo the hacks
was:
Just spent some time wrapping my head around the inner workings of compaction
and tombstoning, with a view to providing guarantees for deleting previous
values of tombstoned keys from kafka within a desired time.
There's a couple of good posts that touch on this:
https://www.confluent.io/blog/handling-gdpr-log-forget/
http://www.shayne.me/blog/2015/2015-06-25-everything-about-kafka-part-2/
Basically, log.cleaner.min.cleanable.ratio or min.cleanable.dirty.ratio is
hijacked to force aggressive compaction (by setting it to 0, or 0.000000001
depending on what you read), and along with segment.ms can provide timing
guarantees that a tombstone will result in any other values for the key will be
deleted within a desired time.
But that sacrifices the utility of min.cleanable.dirty.ratio (and to a lesser
extent, control over segment sizes). On any duplicate key and a new segment
roll it will run compaction, when otherwise it might be preferrable to allow a
more generous dirty.ratio in the case of plain old duplicates.
It would be useful to have control over triggering a compaction without losing
the utility of the dirty.ratio setting.
The pure need here is to specify a minimum time for the log cleaner to run on a
topic that has keys replaced by a tombstone message that are past the minimum
retention times provided by min.compaction.lag.ms
Something like a log.cleaner.max.delay.ms, and an API to trigger compaction,
with some nuances to be fleshed out.
Does this make sense, and sound like it's worth a KIP? I'd be happy to write
something up.
In the mean time, this can be worked around with some duct tape:
* make sure any values you want deleted by a tombstone have passed min
retention configs
* set global log.cleaner.io.max.bytes.per.second to what you want for the
compaction task
* set topic min.cleanable.dirty.ratio=0 for the topic
* set a small segment.ms
* wait for a new segment to roll (ms + a message coming in) and wait for
compaction to kick in. GDPR met!
* undo the hacks
> ability to trigger compaction for tombstoning and GDPR
> ------------------------------------------------------
>
> Key: KAFKA-7137
> URL: https://issues.apache.org/jira/browse/KAFKA-7137
> Project: Kafka
> Issue Type: Wish
> Reporter: Brett Rann
> Priority: Minor
>
> Just spent some time wrapping my head around the inner workings of compaction
> and tombstoning, with a view to providing guarantees for deleting previous
> values of tombstoned keys from kafka within a desired time.
> There's a couple of good posts that touch on this:
> https://www.confluent.io/blog/handling-gdpr-log-forget/
> http://www.shayne.me/blog/2015/2015-06-25-everything-about-kafka-part-2/
> Basically, log.cleaner.min.cleanable.ratio or min.cleanable.dirty.ratio is
> hijacked to force aggressive compaction (by setting it to 0, or 0.000000001
> depending on what you read), and along with segment.ms can provide timing
> guarantees that a tombstone will result in any other values for the key will
> be deleted within a desired time.
> But that sacrifices the utility of min.cleanable.dirty.ratio (and to a lesser
> extent, control over segment sizes). On any duplicate key and a new segment
> roll it will run compaction, when otherwise it might be preferrable to allow
> a more generous dirty.ratio in the case of plain old duplicates.
> It would be useful to have control over triggering a compaction without
> losing the utility of the dirty.ratio setting.
> The pure need here is to specify a minimum time for the log cleaner to run
> (or a maximum time where it doesn't run!) on a topic that has keys replaced
> by a tombstone message that are past the minimum retention times provided by
> min.compaction.lag.ms
> Something like a log.cleaner.max.delay.ms, and an API to trigger compaction,
> with some nuances to be fleshed out.
> Does this make sense, and sound like it's worth a KIP? I'd be happy to write
> something up.
> In the mean time, this can be worked around with some duct tape:
> * make sure any values you want deleted by a tombstone have passed min
> retention configs
> * set global log.cleaner.io.max.bytes.per.second to what you want for the
> compaction task
> * set topic min.cleanable.dirty.ratio=0 for the topic
> * set a small segment.ms
> * wait for a new segment to roll (ms + a message coming in) and wait for
> compaction to kick in. GDPR met!
> * undo the hacks
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