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https://issues.apache.org/jira/browse/PIG-1518?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12898490#action_12898490
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Yan Zhou commented on PIG-1518:
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There is a bigger question at hand. The semantics of OrderedLoadFunc is that
the splits are totally ordered. And BinStorage, InterStorage and PigStorage all
implement that interface through FileInputLoadFunc. Since the combination of
splits as conceived here will definitely destroy the split ordering, if the
combination is disabled for these storages, the feature would be virtually
useless for a majority of use cases.
On the other hand, I'm seeing no use of the comparison capability except for
MergeJoinIndexer's getNext() method, which makes me wonder if the
OrderedLoadFunc can be removed from the FileInputLoadFunc. Semantically,
FileInputLoadFunc should not support the ordering of splits, as Hadoop's
FileInputFormat doesn't. When a need arises like in MergeJoinIndexer, we can
add that extension on. But the change may incur some backward compatibility
issues.
I'm now soliciting comments in this area.
> multi file input format for loaders
> -----------------------------------
>
> Key: PIG-1518
> URL: https://issues.apache.org/jira/browse/PIG-1518
> Project: Pig
> Issue Type: Improvement
> Reporter: Olga Natkovich
> Assignee: Yan Zhou
> Fix For: 0.8.0
>
>
> We frequently run in the situation where Pig needs to deal with small files
> in the input. In this case a separate map is created for each file which
> could be very inefficient.
> It would be greate to have an umbrella input format that can take multiple
> files and use them in a single split. We would like to see this working with
> different data formats if possible.
> There are already a couple of input formats doing similar thing:
> MultifileInputFormat as well as CombinedInputFormat; howevere, neither works
> with ne Hadoop 20 API.
> We at least want to do a feasibility study for Pig 0.8.0.
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