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https://issues.apache.org/jira/browse/NUTCH-1538?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13616621#comment-13616621
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Roland von Herget commented on NUTCH-1538:
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Hi Lufeng,
I'm not sure if I understood your point correctly, but if you mean that some
3rd party plugin may use these fields:
1) In a normal workflow it would be like this:
- fetcher startup
- fetcher gets content via http and stores it to DB
- fetcher shutdown
- parser startup
- parser loads content from DB, parses, store parsed data in DB
- parser shutdown
2) In this discussed workflow (original code):
- fetcher startup
- fetcher loads content from DB
- fetcher gets _new_ content via http (overwriting loaded content from DB)
- fetcher runs parser and stores all in DB
- fetcher shutdown
With my patch, we just touch workflow 2) - skipping step 2 "loading content
from db".
Every field we load in 2)/step 2 should be overwritten by step 3, if not
workflow 1) can't work.
I know, this is not backed by a complete knowledge of the code, but from a
logic point of view it makes sense to me ;)
Just my 2 cents.
> tuning of loaded fields during fetcherJob start-up
> --------------------------------------------------
>
> Key: NUTCH-1538
> URL: https://issues.apache.org/jira/browse/NUTCH-1538
> Project: Nutch
> Issue Type: Improvement
> Components: fetcher
> Affects Versions: 2.1
> Environment: nutch 2.1 / cassandra 1.2.1 / gora-cassandra 0.2 /
> gora-core 0.2.1
> running fetch with parse=true
> Reporter: Roland von Herget
> Attachments: NUTCH-1538-FetcherJob-v1.patch
>
>
> Main problem is, nutch is loading nearly every row & column from DB during
> startup of a fetcherJob when fetcher.parse=true.
> A parserJob needs e.g. the CONTENT field from db, to parse.
> The fetcherJob adds all fields of the parserJob to it's needed fields, if
> running with fetcher.parse=true. [FetcherJob.getFields()]
> If the nutch configuration saves all fetched data to DB
> (fetcher.store.content=true) you'll end up loading GBs of unused content
> during fetcherJob start-up.
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