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https://issues.apache.org/jira/browse/NUTCH-443?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12476357
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Doğacan Güney commented on NUTCH-443:
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Hi Andrzej,
> * in my opinion it's easier to add missing CrawlDatum's (with correctly set
> fetch time) for the new urls to the
> output rather than work-around this by passing around the fetch time in
> metadata, and then again
> compensating in Indexer and CrawlDbReducer for the lack of these fetchDatum-s.
I guess what you mean is pushing STATUS_FETCH_SUCCESS datums to crawl_parse,
right? I can probably do this by changing ParseImpl and adding a new boolean to
it that indicates whether it is fetched or freshly generated in parse.
> * in Fetcher / Fetcher2 you don't pass the signature in case when there is no
> valid Parse output, but in the
> current versions of Fetchers the signature is still calculated and passed in
> datum.setSignature() (which ends
> up in crawl_fetch).
OK, I will fix it.
> * using a generic Map<String, Parse> is IMHO inappropriate, as I indicated
> earlier, especially since this Map > requires special post-processing in
> ParseUtil.processParseMap - and what would happen if I didn't use
> ParseUtil? I think this calls for a special-purpose class (ParseResult?),
> which would encapsulate this
> behavior without exposing it to its users (or even worse - allowing users to
> bypass it). This class would also > help us to avoid somewhat ugly
> "convenience" methods in ParseStatus and ParseImpl - these details would > be
> hidden in one of the constructors of ParseResult.
> * I'm also not sure why we use Map<String, Parse> and not Map<Text, Parse>,
> since in all further
> processing we need to create Text objects ...
If we are going with a special-purpose class, there is one more thing I would
like to change. Consider the case of a zip archive with url
http://foo.bar/baz.zip that contains two files spam.txt, egg.txt. After parsing
this you will return something like <key1, parse of spam.txt>, <key2, parse of
egg.txt> and perhaps <original_url, who knows what>.
Now, whatever key1 and key2 is, they are not really urls to be fetched. So I
want to add another fetch and db status (let's call them STATUS_FETCH_FAKE and
STATUS_DB_FAKE). During parse key1 and key2 will be written with FETCH_FAKE,
and updatedb will write them as DB_FAKE to crawldb. Nutch will still index
things with FAKE status, but generate will never generate them to be fetched.
And updatedb will never change their status to DB_UNFETCHED(since, as I said
before, they can't be fetched).
So, ParseResult will contain a group of <'real' url, parse> and a group of
<'phony' url, parse> pairs.
What do you think?
> * the new section in HtmlParseFilters breaks the loop on encountering the
> first error, and leaves the parse
> results incompletely filtered. It should simply continue - the result is an
> aggregation of more or less
> independent documents that are parsed on their own.
This is the same as the old behavior. Why change it? (There was a bug there,
but I fixed in one of the newer patches)
> * the comment about redirects in Parser.java is misplaced - I think this
> contract should be both defined and > enforced in the Fetcher.
OK.
> And finally, I think this is a significant change in the way how content
> parsers work with the rest of the
> framework, so we should wait with this patch after the 0.9 release - and we
> should push 0.9 out of the door
> really soon ...
Anything to get 0.9 out of the door:)
I will send an updated patch that fixes 1,2 and 4 (and 5 if I am missing
something there) tomorrow unless someone beats me to it. I want to hear what
others think on 3 before doing anything.
Thanks for your review and comments.
> allow parsers to return multiple Parse object, this will speed up the rss
> parser
> --------------------------------------------------------------------------------
>
> Key: NUTCH-443
> URL: https://issues.apache.org/jira/browse/NUTCH-443
> Project: Nutch
> Issue Type: New Feature
> Components: fetcher
> Affects Versions: 0.9.0
> Reporter: Renaud Richardet
> Assigned To: Chris A. Mattmann
> Priority: Minor
> Fix For: 0.9.0
>
> Attachments: NUTCH-443-draft-v1.patch, NUTCH-443-draft-v2.patch,
> NUTCH-443-draft-v3.patch, NUTCH-443-draft-v4.patch, NUTCH-443-draft-v5.patch,
> NUTCH-443-draft-v6.patch, NUTCH-443-draft-v7.patch,
> NUTCH-443.022507.patch.txt, parse-map-core-draft-v1.patch,
> parse-map-core-untested.patch, parsers.diff
>
>
> allow Parser#parse to return a Map<String,Parse>. This way, the RSS parser
> can return multiple parse objects, that will all be indexed separately.
> Advantage: no need to fetch all feed-items separately.
> see the discussion at
> http://www.nabble.com/RSS-fecter-and-index-individul-how-can-i-realize-this-function-tf3146271.html
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