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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10247) Client promises about timestamps
Date Sun, 25 May 2014 05:43:03 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14008283#comment-14008283

Lars Hofhansl commented on HBASE-10247:

Cool... So how do we make progress here? Should I make a patch?

Looking at HBASE-9905, good policies might be:
* seqid
* server_ts
* client_monotonic
* mixed

Might also be good to indicate when the TS field is used for something that is not wall clock
time (so that we do not attempt to use TTL, etc).

I could start with the config framework (that is simple anyway), and adding "server_ts", "mixed",
and "client_monotonic". "server_ts" would the default for new tables. We can then add seqid
as that gets ready.

> Client promises about timestamps
> --------------------------------
>                 Key: HBASE-10247
>                 URL: https://issues.apache.org/jira/browse/HBASE-10247
>             Project: HBase
>          Issue Type: Brainstorming
>            Reporter: Lars Hofhansl
>            Priority: Minor
> This is to start a discussion about timestamp promises declared per table of CF.
> For example if a client promises only monotonically increasing timestamps (or no custom
set timestamps) and VERSIONS=1, we can aggressively and easily remove old versions of the
same row/fam/col from the memstore before we flush, just by supplying a comparator that ignores
the timestamp (i.e. two KV just differing by TS would be considered equal).
> That would increase the performance of counters significantly.

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