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https://issues.apache.org/jira/browse/PHOENIX-3744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16035624#comment-16035624
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ASF GitHub Bot commented on PHOENIX-3744:
-----------------------------------------
Github user JamesRTaylor commented on the issue:
https://github.com/apache/phoenix/pull/239
Had an offline discussion with @lhofhansl and he brought up the use case of
having a snapshot at a known point in time (i.e. midnight last night) and
wanting to run Phoenix queries over it through MR. That seems like a good
reason to pass in the snapshot name rather than build it when the MR starts.
I'll commit this into 4.x and master. Nice work, @akshita-malhotra!
> Support snapshot scanners for MR-based queries
> ----------------------------------------------
>
> Key: PHOENIX-3744
> URL: https://issues.apache.org/jira/browse/PHOENIX-3744
> Project: Phoenix
> Issue Type: Bug
> Reporter: James Taylor
> Assignee: Akshita Malhotra
> Attachments: PHOENIX-3744.patch, PHOENIX-3744.patch,
> PHOENIX-3744.patch
>
>
> HBase support scanning over snapshots, with a SnapshotScanner that accesses
> the region directly in HDFS. We should make sure that Phoenix can support
> that.
> Not sure how we'd want to decide when to run a query over a snapshot. Some
> ideas:
> - if there's an SCN set (i.e. the query is running at a point in time in the
> past)
> - if the memstore is empty
> - if the query is being run at a timestamp earlier than any memstore data
> - as a config option on the table
> - as a query hint
> - based on some kind of optimizer rule (i.e. based on estimated # of bytes
> that will be scanned)
> Phoenix typically runs a query at the timestamp at which it was compiled. Any
> data committed after this time should not be seen while a query is running.
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