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https://issues.apache.org/jira/browse/PHOENIX-3744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15981853#comment-15981853
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Akshita Malhotra edited comment on PHOENIX-3744 at 4/24/17 8:41 PM:
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Parallel Scan grouper is extended to differentiate the functionality for
getting region boundaries
Added integration test, compares the snapshot read result with the result from
select query by setting CurrentScn value.
the configuration parameter is the snapshot name key, if set do a snapshot read
Used an existing PhoenixIndexDBWritable class for the purpose of testing, will
add a new one as I will add more tests.
ExpressionProjector functionality is extended for snapshots as the keyvalue
format returned from TableSnapshotScanner is different from ClientScanner and
therefore not properly interrupted by Phoenix thereby returning null in case of
projected columns.
For the same table, following shows the different format of the keyvalues:
ClientScanner:
keyvalues={AAPL/_v:\x00\x00\x00\x01/1493061452132/Put/vlen=7/seqid=0/value=�SSDD��}
TableSnapshotScanner:
keyvalues={AAPL/0:\x00\x00\x00\x00/1493061673859/Put/vlen=1/seqid=4/value=x,
AAPL/0:\x80\x0B/1493061673859/Put/vlen=4/seqid=4/value=SSDD}
To DO:
Add more integration tests to cover different scenarios such as where clause etc
[~jamestaylor]
was (Author: akshita.malhotra):
Parallel Scan grouper is extended to differentiate the functionality for
getting region boundaries
Added integration test, compares the snapshot read result with the result from
select query by setting CurrentScn value.
the configuration parameter is the snapshot name key, if set do a snapshot read
Used an existing PhoenixIndexDBWritable class for the purpose of testing, will
add a new one as I will add more tests.
ExpressionProjector functionality is extended for snapshots as the keyvalue
format returned from TableSnapshotScanner is different from ClientScanner and
therefore not properly interrupted by Phoenix thereby returning null in case of
projected columns.
For the same table, following shows the different format of the keyvalues:
ClientScanner:
keyvalues={AAPL/_v:\x00\x00\x00\x01/1493061452132/Put/vlen=7/seqid=0/value=�SSDD��}
TableSnapshotScanner:
keyvalues={AAPL/0:\x00\x00\x00\x00/1493061673859/Put/vlen=1/seqid=4/value=x,
AAPL/0:\x80\x0B/1493061673859/Put/vlen=4/seqid=4/value=SSDD}
To DO:
Add more integration tests to cover different scenarios such as where clause etc
> 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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