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https://issues.apache.org/jira/browse/NUTCH-2455?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16278926#comment-16278926
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Sebastian Nagel commented on NUTCH-2455:
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Hi [[email protected]], you're right, it's not possible to check for
the global -topN limit with secondary sorting. The only solution I see is to
split the "select" job into two steps/jobs:
# existing Selector.map(), partition by URL (not host/domain/IP which avoids
some extra work), apply topN limit in reduce()
# read output from job 1 and add HostDb entries as MultipleInput, secondary
sorting by host and score, reducer: apply per-host/domain/IP limits (limit ev.
taken from HostDb), assign segments
> Speed up the merging of HostDb entries for variable fetch delay
> ---------------------------------------------------------------
>
> Key: NUTCH-2455
> URL: https://issues.apache.org/jira/browse/NUTCH-2455
> Project: Nutch
> Issue Type: Improvement
> Components: generator
> Affects Versions: 1.13
> Reporter: Markus Jelsma
> Attachments: NUTCH-2455.patch
>
>
> Citing Sebastian at NUTCH-2420:
> ??The correct solution would be to use <host,score> pairs as keys in the
> Selector job, with a partitioner and secondary sorting so that all keys with
> same host end up in the same call of the reducer. If values can also hold a
> HostDb entry and the sort comparator guarantees that the HostDb entry
> (entries if partitioned by domain or IP) comes in front of all CrawlDb
> entries. But that would be a substantial improvement...??
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