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https://issues.apache.org/jira/browse/HBASE-24749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17163069#comment-17163069
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Michael Stack commented on HBASE-24749:
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On where to write ROOT hfile list, when no zk, I suppose you can't adapt the 
ROOT Region to write a manifest file that gets updated as file set changes 
because you don't have sufficient guarantees from storage? Will your WAL 
filesystem have better semantics? On events such as flush and compaction, we 
write markers to the WAL w/ notes listing files that participated in the event. 
On recovery, we read these events completing compactions if all participants 
present and it looked like we crashed after compaction completed but before we 
got to slot the new files into place and remove the old. Could you use this 
mechanism – aggregating result of hfile list changes (flushes/compactions)? Or 
add an event of your own that would make your job easier?

> Direct insert HFiles and Persist in-memory HFile tracking
> ---------------------------------------------------------
>
>                 Key: HBASE-24749
>                 URL: https://issues.apache.org/jira/browse/HBASE-24749
>             Project: HBase
>          Issue Type: Umbrella
>          Components: Compaction, HFile
>    Affects Versions: 3.0.0-alpha-1
>            Reporter: Tak-Lon (Stephen) Wu
>            Priority: Major
>              Labels: design, discussion, objectstore, storeFile, storeengine
>         Attachments: 1B100m-25m25m-performance.pdf, Apache HBase - Direct 
> insert HFiles and Persist in-memory HFile tracking.pdf
>
>
> We propose a new feature (a new store engine) to remove the {{.tmp}} 
> directory used in the commit stage for common HFile operations such as flush 
> and compaction to improve the write throughput and latency on object stores. 
> Specifically for S3 filesystems, this will also mitigate read-after-write 
> inconsistencies caused by immediate HFiles validation after moving the 
> HFile(s) to data directory.
> Please see attached for this proposal and the initial result captured with 
> 25m (25m operations) and 1B (100m operations) YCSB workload A LOAD and RUN, 
> and workload C RUN result.
> The goal of this JIRA is to discuss with the community if the proposed 
> improvement on the object stores use case makes senses and if we miss 
> anything should be included.
> Improvement Highlights
>  1. Lower write latency, especially the p99+
>  2. Higher write throughput on flush and compaction 
>  3. Lower MTTR on region (re)open or assignment 
>  4. Remove consistent check dependencies (e.g. DynamoDB) supported by file 
> system implementation



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