[
https://issues.apache.org/jira/browse/HBASE-20952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16609598#comment-16609598
]
stack commented on HBASE-20952:
-------------------------------
Reading doc. (comments nor copy/paste allowed -- please fix... add reference
here and author), the study of other logging systems resulted in "...no
significant influence on HBase WAL API design." though above Josh says " I can
say that a significant portion of the direction was strongly influenced by
Apache DistributedLog".
Then we have a listing of the classes involved writing the WAL with stuff like
this:
{{WAL implements WALFileLengthProvider}}
Nothing on "What was the reasoning behind this API?"[Josh] or what it is -- its
the WAL we have already? (Why even have a WALFileLengthProvider and not just
add a length method on the WAL Interface? Does Replication just need lengths to
work? If so, discussion?).
Then comes 'design considerations'. #1 is not a design consideration but a note
that code has been refactored. #2 is that we should be able to choose WAL via
Configuration. #3 is an aspirational, abstract classes should not be tied to fs
implementation, and #4 is a note on WAL metadata capability, a concept first
mentioned here but unexplained/justified till later.
I see no discussion of 'region' entity in here.
> Re-visit the WAL API
> --------------------
>
> Key: HBASE-20952
> URL: https://issues.apache.org/jira/browse/HBASE-20952
> Project: HBase
> Issue Type: Sub-task
> 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.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
