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Posted to dev@phoenix.apache.org by "James Taylor (JIRA)" <ji...@apache.org> on 2017/03/21 23:33:41 UTC
[jira] [Updated] (PHOENIX-3744) Support snapshot scanners for
MR-based queries
[ https://issues.apache.org/jira/browse/PHOENIX-3744?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
James Taylor updated PHOENIX-3744:
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Summary: Support snapshot scanners for MR-based queries (was: Support snapshot scanners)
> 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
>
> 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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