hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14070) Hybrid Logical Clocks for HBase
Date Wed, 16 Mar 2016 03:43:33 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14070?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15196699#comment-15196699
] 

stack commented on HBASE-14070:
-------------------------------

bq. The tracker just drops the older sequence id. It doesn't drop both. 

I should have been more clear. These are two legit edits that just happen to arrive at the
same time. Let them be Puts that we'd want to aggregate at read time for example.

bq. So putting sequence id through everything would be a pretty big behavioral change as there's
no other way to replace a cell at a timestamp.

Delete and then Put at the explicit coordinate only now that sequenceid is respected, you
can actually overwrite the delete.

> 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#



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message