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https://issues.apache.org/jira/browse/HBASE-20952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16632147#comment-16632147
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Josh Elser commented on HBASE-20952:
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{quote}This aspect is thin to absent (IMO).
{quote}
That's fair. It's hard to get this all correct and down on paper without 
sending a (literal) book out for review. I see Ted is already on making some 
modifications, and I'll make some passes over the comments too. Appreciate your 
input, boss.

I'll be focusing on your review points around "how things work now" to polish 
that up. Will make it easier to then shift into beefing up the parts on "what 
to change".

> Re-visit the WAL API
> --------------------
>
>                 Key: HBASE-20952
>                 URL: https://issues.apache.org/jira/browse/HBASE-20952
>             Project: HBase
>          Issue Type: Improvement
>          Components: wal
>            Reporter: Josh Elser
>            Priority: Major
>         Attachments: 20952.v1.txt
>
>
> Take a step back from the current WAL implementations and think about what an 
> HBase WAL API should look like. What are the primitive calls that we require 
> to guarantee durability of writes with a high degree of performance?
> The API needs to take the current implementations into consideration. We 
> should also have a mind for what is happening in the Ratis LogService (but 
> the LogService should not dictate what HBase's WAL API looks like RATIS-272).
> Other "systems" inside of HBase that use WALs are replication and 
> backup&restore. Replication has the use-case for "tail"'ing the WAL which we 
> should provide via our new API. B&R doesn't do anything fancy (IIRC). We 
> should make sure all consumers are generally going to be OK with the API we 
> create.
> The API may be "OK" (or OK in a part). We need to also consider other methods 
> which were "bolted" on such as {{AbstractFSWAL}} and 
> {{WALFileLengthProvider}}. Other corners of "WAL use" (like the 
> {{WALSplitter}} should also be looked at to use WAL-APIs only).
> We also need to make sure that adequate interface audience and stability 
> annotations are chosen.



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