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https://issues.apache.org/jira/browse/TAJO-178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13765308#comment-13765308
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Hyunsik Choi edited comment on TAJO-178 at 9/12/13 9:53 AM:
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The current issue title represents better the submitted patch.
Also, I agree with the main purpose of this feature and its promising. Even
though the current throughput of this patch is similar to the existing one, it
will be a key feature for efficient I/O when we fully optimize it.
Later, we could also improve this to something like cooperative scans for
multiple queries.
I'll take a look at this patch today night.
was (Author: hyunsik):
The current issue title represents better the submitted patch.
Also, I agree with the main purpose of this feature and its promising. Even
though the current throughput of this patch is similar to the existing one, it
will be a key feature for efficient I/O when we fully optimize it.
Later, we could also improve this to something like cooperative scans for
multiple queries.
I'll take a look at this patch today's night.
> Implements StorageManager for scanning asynchronously
> -----------------------------------------------------
>
> Key: TAJO-178
> URL: https://issues.apache.org/jira/browse/TAJO-178
> Project: Tajo
> Issue Type: Improvement
> Components: storage
> Affects Versions: 0.2-incubating
> Reporter: hyoungjunkim
> Assignee: hyoungjunkim
> Attachments: TAJO-178_1.path, TAJO-178.patch_2, TAJO-178.path,
> tajo_storage_manager.png
>
>
> The current StorageManager does not provide scan scheduling function. All
> scan operations run concurrently. This is the cause of random disk access and
> disk read performance is not good.
> The proposed StorageManager is based on double buffering. Each disk has a
> scheduler to schedule by order of scanned adjust. Each Scanner has a
> InputStream and a Tuple pool. The next() operation of ScanNode is blocked
> until Tuple pool is filled. Assigned Scanner by the scheduler read data(xMB)
> and fills Tuple Pool and notifies to next() operation. After scanning Scanner
> re-enter DiskScanQueue.
> In this way Scanner can pass column vector to Vectorized Query Engine.
> See the attached file.
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