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https://issues.apache.org/jira/browse/KUDU-1704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15685765#comment-15685765
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Alexey Serbin edited comment on KUDU-1704 at 11/22/16 5:40 AM:
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A couple of questions to clarify:
For the new scan mode, does it make sense to have the following semantics for
scan timestamp:
* explicitly specified: in the corresponding tablet, select server's first
operation which happens after the specified timestamp
* not specified/omitted: in the corresponding tablet, select server's latest
committed operation
?
Also, there is a question: what timestamp do we choose if the first tablet
server contacted among those hosting the tablet does not have any committed
operations yet?
was (Author: aserbin):
A couple of questions to clarify:
For the new scan mode, it might make sense to have the following semantics for
scan timestamp:
* explicitly specified: in the corresponding tablet, select server's first
operation which happens after the specified timestamp
* not specified/omitted: in the corresponding tablet, select server's latest
committed operation
Also, there is a question: what timestamp do we choose if the first tablet
server contacted among those hosting the tablet does not have any committed
operations yet?
> Add a new read mode to perform bounded staleness snapshot reads
> ---------------------------------------------------------------
>
> Key: KUDU-1704
> URL: https://issues.apache.org/jira/browse/KUDU-1704
> Project: Kudu
> Issue Type: Sub-task
> Affects Versions: 1.1.0
> Reporter: David Alves
> Assignee: Alexey Serbin
>
> It would be useful to be able to perform snapshot reads at a timestamp that
> is higher than a client provided timestamp, thus improving recency, but lower
> that the server's oldest inflight transaction, thus minimizing the scan's
> chance to block.
> Such a mode would not guarantee linearizability, but would still allow for
> client-local read-your-writes, which seems to be one of the properties users
> care about the most.
> This should likely be the new default read mode for scanners.
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