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https://issues.apache.org/jira/browse/HDDS-4222?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17192947#comment-17192947
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Yiqun Lin commented on HDDS-4222:
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Thanks for attaching the dir cache design, [~rakeshr]!
I agree most of the current design details.
>For the consistency part, this is a very good point and will take care during
>the implementation phase. I was thinking to update the cache during write and
>read paths to avoid additional cache refresh cycle.
I'm +1 for this way as current initial implementation.
>Rename and Delete ops will require only one entry update as it maintains
>similar structure in the DB Directory Table.
Delete ops is also not friendly for the Approach-3.
Example:
*DirTable:*
|CacheKey(PathElement)|{color:#ff8b00}*ObjectID*{color}|
|512/a|1025|
|1025/b|1026|
|1026/c|1027|
|1027/d|1028|
|1025/e|1029|
If we delete dir 512/a, it should lookup the whole dir cache and find the key
which parent objectID is 1025 and then be deleted. So delete ops here seems
still the very expensive ops.
>Delete ops will require only one entry update
If we use the sync delete way, it will not update for only one entry (as
explained in above example).
So is this mean the async delete way here, like bucket key deletion mechanism?
1) Mark the delete key,(add prefix in key to let it not be accessed)
2) Async to remove these keys that needed to be deleted.
> [OzoneFS optimization] Provide a mechanism for efficient path lookup
> --------------------------------------------------------------------
>
> Key: HDDS-4222
> URL: https://issues.apache.org/jira/browse/HDDS-4222
> Project: Hadoop Distributed Data Store
> Issue Type: New Feature
> Reporter: Rakesh Radhakrishnan
> Assignee: Rakesh Radhakrishnan
> Priority: Major
> Attachments: Ozone FS Optimizations - Efficient Lookup using cache.pdf
>
>
> With the new file system HDDS-2939 like semantics design it requires multiple
> DB lookups to traverse the path component in top-down fashion. This task to
> discuss use cases and proposals to reduce the performance penalties during
> path lookups.
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