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https://issues.apache.org/jira/browse/HBASE-16838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15656277#comment-15656277
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Duo Zhang commented on HBASE-16838:
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{quote}
Is a Scan always against a Region (is the Region redundant?).
{quote}
A scan can cross regions, the AsyncScanRegionRpcRetryingCaller is only used to
scan one region. During a scan we may create many
AsyncScanRegionRpcRetryingCallers. AsyncScanOneRegionRpcRetryingCaller maybe
better?
{quote}
Looking at the Response, we need Scan in there? The Scan in Response is
different from originalScan?
{quote}
They are the same. But I think it is a little confusing that we use the
originalScan in AsyncClientScanner but modify it at another place. But anyway,
we do change it so people can not use it as 'original'... Let me add some
javadoc here...
{quote}
I think you should stick the above comment on the scan timeout so it is clear
what the scan timeout means. It helps.
{quote}
I've add some comments in AsyncConnectionConfiguration. Let me add the above
comments too.
{quote}
Is there example code on how I'd do an async Scan? I create a ScanConsumer and
pass it in then it will get called with Results as the Scan progresses? The
AsyncTable#scan returns immediately? Perhaps stick it in javadoc for the scan
method? Is SimpleScanObserver a good example or just a stop gap with its queue?
{quote}
I plan to introduce a example when implementing getScanner, where I plan to add
flow control support. This method is used to write high performance
event-driven program so it is not very user friendly... [~carp84] also claimed
that even for other method such as get and put, complete the CompletableFuture
insdie the thread of the rpc framework is not safe as user may also do time
consuming work when consuming the CompletableFuture. Maybe we need a new
'SafeAsyncTable' interface? Or change the name of this interface to
'RawAsyncTable' or 'UnsafeAsyncTable'? As the async client is still marked as
Unstable, I think we can do this in a follow on issue.
{quote}
Dont kill me but should ScanConsumer be ScanResultConsumer (can do in followup
if makes sense) or just ScanResult?
{quote}
I think it should be ScanResultConsumer as I've already introduce a
'ScanResultCache'(What's wrong with my brain...)
{quote}
CompleteResultScanResultCache should be CompleteScanResultCache to match
AllowPartialScanResultCache?
{quote}
Fine. Will change.
> Implement basic scan
> --------------------
>
> Key: HBASE-16838
> URL: https://issues.apache.org/jira/browse/HBASE-16838
> Project: HBase
> Issue Type: Sub-task
> Affects Versions: 2.0.0
> Reporter: Duo Zhang
> Assignee: Duo Zhang
> Fix For: 2.0.0
>
> Attachments: HBASE-16838-v1.patch, HBASE-16838-v2.patch,
> HBASE-16838-v3.patch, HBASE-16838.patch
>
>
> Implement a scan works like the grpc streaming call that all returned results
> will be passed to a ScanConsumer. The methods of the consumer will be called
> directly in the rpc framework threads so it is not allowed to do time
> consuming work in the methods. So in general only experts or the
> implementation of other methods in AsyncTable can call this method directly,
> that's why I call it 'basic scan'.
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