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https://issues.apache.org/jira/browse/OAK-5253?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15735027#comment-15735027
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Julian Sedding commented on OAK-5253:
-------------------------------------
Thanks [~amitjain]. I am wondering if we could compare {{Blob#getReference()}},
but the contract is not very clear regarding its equality semantics. Basically
I believe that we need to use something that is delegated to the {{BlobStore}}
implementation.
A change in {{SegmentBlob}} would suffer from the same problem as a change in
{{AbstractBlob}}. It is backed by an arbitrary {{BlobStore}} implementation,
thus we cannot rely on the semantics of {{Blob#getContentIdentity()}}, as it
may change depending on the backing {{BlobStore}}.
I have posted on the mailing list to see if someone can clarify whether
{{Blob#getReference()}} is suited.
> Optimize AbstractBlob#equal to not do content equals when possible
> ------------------------------------------------------------------
>
> Key: OAK-5253
> URL: https://issues.apache.org/jira/browse/OAK-5253
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: blob
> Reporter: Amit Jain
> Assignee: Amit Jain
> Fix For: 1.6, 1.5.16, 1.4.11
>
> Attachments: OAK-5253.1.patch
>
>
> AbstractBlob#equals tries to match content when length is equal and content
> identities is not null and different. Matching content triggers an expensive
> download of binaries for S3DataStore.
> Since, right now the content identity is the content hash the check can be
> short -circuited when the content identities is not null and not equal to
> return false.
> This can be revisited if we change the identity to something different.
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