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From "Dave Latham (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15181) A simple implementation of date based tiered compaction
Date Mon, 01 Feb 2016 23:59:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15181?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15127284#comment-15127284
] 

Dave Latham commented on HBASE-15181:
-------------------------------------

Those are great questions, Vladimir - I hope people who know better chime in and confirm /
deny.  Poking at the issues that Clara linked, I can speculate:

The default compaction algorithm at the time (Ratio based?) was intended to handle stores
with a shape where the older files were larger than recent files, so it sounds the policy
would not intelligently handle a smaller bulk load file that is sorted to be oldest and end
up doing a large wasteful compaction.

For contiguous-only compactions, I think that's because the sequence IDs are only stored per-file,
not per-cell.  So if you want to compare two Cell sequence IDs for identical keys, then you
need to have a strict ordering on HFile sequence IDs.  If you compact out-of-order HFiles,
then you don't have strictly ordered sequence IDs any more.

Both speculation.

> A simple implementation of date based tiered compaction
> -------------------------------------------------------
>
>                 Key: HBASE-15181
>                 URL: https://issues.apache.org/jira/browse/HBASE-15181
>             Project: HBase
>          Issue Type: New Feature
>          Components: Compaction
>            Reporter: Clara Xiong
>            Assignee: Clara Xiong
>             Fix For: 2.0.0
>
>         Attachments: HBASE-15181-v1.patch, HBASE-15181-v2.patch
>
>
> This is a simple implementation of date-based tiered compaction similar to Cassandra's
for the following benefits:
> 1. Improve date-range-based scan by structuring store files in date-based tiered layout.
> 2. Reduce compaction overhead.
> 3. Improve TTL efficiency.
> Perfect fit for the use cases that:
> 1. has mostly date-based date write and scan and a focus on the most recent data. 
> 2. never or rarely deletes data.
> Out-of-order writes are handled gracefully so the data will still get to the right store
file for time-range-scan and re-compacton with existing store file in the same time window
is handled by ExploringCompactionPolicy.
> Time range overlapping among store files is tolerated and the performance impact is minimized.
> Configuration can be set at hbase-site or overriden at per-table or per-column-famly
level by hbase shell.
> Design spec is at https://docs.google.com/document/d/1_AmlNb2N8Us1xICsTeGDLKIqL6T-oHoRLZ323MG_uy8/edit?usp=sharing



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