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https://issues.apache.org/jira/browse/HBASE-26458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17445104#comment-17445104
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Viraj Jasani commented on HBASE-26458:
--------------------------------------
Added testing details here:
[https://github.com/apache/hbase/pull/3852#issuecomment-971465945]
To sum up,
# TTL with negative values < {{{}-1{}}}, will stay forever regardless of any
server side config changes.
# TTL with positive values will be gone after TTL expires.
# Snapshot created without specifying TTL will always have TTL value
represented by config {{{}hbase.master.snapshot.ttl{}}}.
# From client side, TTL values {{0}} or {{-1}} should not be provided because
they will be treated as snapshot without TTL (same as point {{3}} above) and
hence will represent TTL as per value represented by config
{{{}hbase.master.snapshot.ttl{}}}.
I think we have doc with details of server side configs
{{hbase.master.cleaner.snapshot.interval}} and
{{{}hbase.master.snapshot.ttl{}}}. From client viewpoint, we should mention
above 4 points.
Also, it's bit complex to resolve point {{4}} completely because in order to
represent value as default TTL, we will have to either sacrifice the meaning of
0 or -1 (if not both) in the best case. I think as long as the above mentioned
points are taken care of, we should not see any TTL related issues.
Note: updating default value in proto message is considered as incompatible
change. Even if we want to present only either 0 or 1 as default TTL, we will
need changes to proto definition and be careful of the issues that could arise
from rolling upgrade. Given the incompatibility cost, I believe we should
rather follow the behaviour mentioned in above 4 points :(
> Value of hbase.master.snapshot.ttl is not used
> ----------------------------------------------
>
> Key: HBASE-26458
> URL: https://issues.apache.org/jira/browse/HBASE-26458
> Project: HBase
> Issue Type: Bug
> Components: snapshots
> Affects Versions: 1.7.1, 2.4.8
> Reporter: Joel Swiatek
> Assignee: Joel Swiatek
> Priority: Minor
> Fix For: 1.7.1, 2.4.8
>
> Attachments:
> branch-1-0001-HBASE-22458-Add-UNSET_SNAPSHOT_PROP-and-fix-TTL-defa.patch,
> branch-2-0001-HBASE-22458-Add-UNSET_SNAPSHOT_PROP-and-fix-TTL-defa.patch,
> master-0001-HBASE-22458-Add-UNSET_SNAPSHOT_PROP-and-fix-TTL-defa.patch
>
> Original Estimate: 120h
> Remaining Estimate: 120h
>
> When creating a snapshot, users can explicitly specify the TTL to be used. If
> no TTL is specified, then the SnapshotDescription is initially created with a
> TTL of -1 to indicate FOREVER.
> When the SnapshotDescription runs through SnapshotDescriptionUtils#validate,
> the TTL is checked to see if the default value of hbase.master.snapshot.ttl
> should be applied. The value from the config is only applied if the TTL == 0,
> but it should be -1.
> This has another nasty side-effect: any user who creates a snapshot and
> explicitly sets \{TTL => 0} will find that their snapshot gets its TTL from
> hbase.master.snapshot.TTL.
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