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https://issues.apache.org/jira/browse/HBASE-24749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17188056#comment-17188056
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Tak-Lon (Stephen) Wu commented on HBASE-24749:
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{quote} # When (re)open, ROOT region only cares HFiles in the data directory of 
ROOT Region (relies on the MVCC protection of what files should be included). 
 # HFile Tracking of hbase:meta are written to ROOT region (similar to how the 
meta location is being handled), and this tracking metadata is being protected 
by the WAL of ROOT Region and HFiles in the data directory of ROOT Region.
 # HFile Tracking of any other tables are being updated to a column family 
cf:storefile in hbase:meta. The only read extensively period is during the 
region open and region assignment.{quote}
hey guys, did you guys see any red flag on the last comment about scanning the 
file system directly for the ROOT region ? [~stack]  [~zyork]  [~anoop.hbase] 
[~zhangduo]  ?

> 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
>            Assignee: 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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