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https://issues.apache.org/jira/browse/HBASE-14070?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14640219#comment-14640219
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stack commented on HBASE-14070:
-------------------------------

Nice javadoc

"Timestamps from cells should always be interpreted by the table's Timestamp 
type so that timestamps given by HBase servers can be converted to wall clock."

This implies Cell is no longer standalone. It needs a context so its timestamp 
is interpreted appropriately.



> Hybrid Logical Clocks for HBase
> -------------------------------
>
>                 Key: HBASE-14070
>                 URL: https://issues.apache.org/jira/browse/HBASE-14070
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Enis Soztutar
>            Assignee: Enis Soztutar
>         Attachments: HybridLogicalClocksforHBaseandPhoenix.docx, 
> HybridLogicalClocksforHBaseandPhoenix.pdf
>
>
> HBase and Phoenix uses systems physical clock (PT) to give timestamps to 
> events (read and writes). This works mostly when the system clock is strictly 
> monotonically increasing and there is no cross-dependency between servers 
> clocks. However we know that leap seconds, general clock skew and clock drift 
> are in fact real. 
> This jira proposes using Hybrid Logical Clocks (HLC) as an implementation of 
> hybrid physical clock + a logical clock. HLC is best of both worlds where it 
> keeps causality relationship similar to logical clocks, but still is 
> compatible with NTP based physical system clock. HLC can be represented in 
> 64bits. 
> A design document is attached and also can be found here: 
> https://docs.google.com/document/d/1LL2GAodiYi0waBz5ODGL4LDT4e_bXy8P9h6kWC05Bhw/edit#



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