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https://issues.apache.org/jira/browse/HIVE-2121?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13025919#comment-13025919
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Namit Jain commented on HIVE-2121:
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A few other comments:
The percentage of data read is currently a function
of the split size - we should mark the last split
specially, and only read the required data at runtime.
I mean, if we have only 1 split, and we need to sample
10% of the data, there should be a way to do so. Currently,
it seems impossible.
> Input Sampling By Splits
> ------------------------
>
> Key: HIVE-2121
> URL: https://issues.apache.org/jira/browse/HIVE-2121
> Project: Hive
> Issue Type: New Feature
> Reporter: Siying Dong
> Assignee: Siying Dong
> Attachments: HIVE-2121.1.patch, HIVE-2121.2.patch, HIVE-2121.3.patch,
> HIVE-2121.4.patch
>
>
> We need a better input sampling to serve at least two purposes:
> 1. test their queries against a smaller data set
> 2. understand more about how the data look like without scanning the whole
> table.
> A simple function that gives a subset splits will help in those cases. It
> doesn't have to be strict sampling.
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