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https://issues.apache.org/jira/browse/ZOOKEEPER-1573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13824156#comment-13824156
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Thawan Kooburat commented on ZOOKEEPER-1573:
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Probably need a comment from other people as well. We disable this check in
our prod system because we have some other way of detecting data inconsistency.
This check has shown to catch a real bug but it can also raise false possible
in certain usage pattern.
> Unable to load database due to missing parent node
> --------------------------------------------------
>
> Key: ZOOKEEPER-1573
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1573
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.4.3, 3.5.0
> Reporter: Thawan Kooburat
> Attachments: ZOOKEEPER-1573.patch
>
>
> While replaying txnlog on data tree, the server has a code to detect missing
> parent node. This code block was last modified as part of ZOOKEEPER-1333. In
> our production, we found a case where this check is return false positive.
> The sequence of txns is as follows:
> zxid 1: create /prefix/a
> zxid 2: create /prefix/a/b
> zxid 3: delete /prefix/a/b
> zxid 4: delete /prefix/a
> The server start capturing snapshot at zxid 1. However, by the time it
> traversing the data tree down to /prefix, txn 4 is already applied and
> /prefix have no children.
> When the server restore from snapshot, it process txnlog starting from zxid
> 2. This txn generate missing parent error and the server refuse to start up.
> The same check allow me to discover bug in ZOOKEEPER-1551, but I don't know
> if we have any option beside removing this check to solve this issue.
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