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https://issues.apache.org/jira/browse/HDFS-7337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14360018#comment-14360018
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Kai Zheng commented on HDFS-7337:
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Thanks [~zhz] for the detailed clarifying. It's great we're much aligned !
bq.Is there another JIRA handling the management of loaded schemas? If not
maybe we can consider ECSchemaSuite?
I got your point about {{ECSchemaSuite}}. HDFS-7866 was the JIRA that does the
job you're saying. I do have some rough codes for it where {{ECSchemaManager}}
is the core part. {{ECSchemaManager}} basically wraps a map and contains all
the ACTIVE schemas synced between NN metadata and predefined. At one side it
serves for dfsadmin to request reloading predefined schemas (by HADOOP-11664)
in authorization controlled way, at the other side it also serves for client
requests for schemas list and detailed definition. I will rethink about the
codes and see {{ECSchemaSuite}} works the better, or borrow the benefits. By
the way HDFS-7859 is used to persist schemas in NN metadata. Anything more for
us to fill the gap ?
bq.Actually even if hard-code all schemas it's still dangerous to pass only the
schema ID
I agree. Thanks for the confirmation. With schema object passed around and
available in DN and client, we can perform schema-driven encoding and decoding,
which will be much safer and flexible.
Currently I'm working from bottom up and hopefully it wouldn't be too long to
achieve to NN and get all the work hooked together.
> Configurable and pluggable Erasure Codec and schema
> ---------------------------------------------------
>
> Key: HDFS-7337
> URL: https://issues.apache.org/jira/browse/HDFS-7337
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Zhe Zhang
> Assignee: Kai Zheng
> Attachments: HDFS-7337-prototype-v1.patch,
> HDFS-7337-prototype-v2.zip, HDFS-7337-prototype-v3.zip,
> PluggableErasureCodec-v2.pdf, PluggableErasureCodec.pdf
>
>
> According to HDFS-7285 and the design, this considers to support multiple
> Erasure Codecs via pluggable approach. It allows to define and configure
> multiple codec schemas with different coding algorithms and parameters. The
> resultant codec schemas can be utilized and specified via command tool for
> different file folders. While design and implement such pluggable framework,
> it’s also to implement a concrete codec by default (Reed Solomon) to prove
> the framework is useful and workable. Separate JIRA could be opened for the
> RS codec implementation.
> Note HDFS-7353 will focus on the very low level codec API and implementation
> to make concrete vendor libraries transparent to the upper layer. This JIRA
> focuses on high level stuffs that interact with configuration, schema and etc.
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