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https://issues.apache.org/jira/browse/NUTCH-466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12501921
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Doğacan Güney edited comment on NUTCH-466 at 6/6/07 6:08 AM:
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I still haven't tested it yet, but the code looks solid. I have a couple of
comments, though:
* One can't define order of execution for ParseFilter-s. It seems we always
need it in one way or another in filters so it may be good to just add ordering
and be done with it.
* ParseFilters.filter method throws IOException. I think it will be better if
it throws a ParseFilterException or whatever, keeping in spirit with
IndexingFilters -> IndexingException and ScoringFilters ->
ScoringFilterException.
* There are few uses of iterating over Map.keySet() then getting the value with
Map.get(key). FindBugs suggests that it is better to iterate over
Map.entrySet() in these cases.
* When someone requests more than 1 part-data, we start a couple of threads,
receive data and join threads. Nutch also does this for summary. Is starting
and joining threads again and again a problem? Especially, if you are
clustering you may end up starting and joining _100_ threads for each query.
Perhaps a thread pool? This is not completely related to this patch, it is just
something that bugs me.
* I just realized that there is no ParseFilter class either :)
was:
I still haven't tested it yet, but the code looks solid. I have a couple of
comments, though:
* One can't define order of execution for ParseFilter-s. It seems we always
need it in one way or another in filters so it may be good to just add ordering
and be done with it.
* ParseResult.filter method throws IOException. I think it will be better if it
throws a ParseFilterException or whatever, keeping in spirit with
IndexingFilters -> IndexingException and ScoringFilters ->
ScoringFilterException.
* There are few uses of iterating over Map.keySet() then getting the value with
Map.get(key). FindBugs suggests that it is better to iterate over
Map.entrySet() in these cases.
* When someone requests more than 1 part-data, we start a couple of threads,
receive data and join threads. Nutch also does this for summary. Is starting
and joining threads again and again a problem? Especially, if you are
clustering you may end up starting and joining _100_ threads for each query.
Perhaps a thread pool? This is not completely related to this patch, it is just
something that bugs me.
* I just realized that there is no ParseFilter class either :)
> Flexible segment format
> -----------------------
>
> Key: NUTCH-466
> URL: https://issues.apache.org/jira/browse/NUTCH-466
> Project: Nutch
> Issue Type: Improvement
> Components: searcher
> Affects Versions: 1.0.0
> Reporter: Andrzej Bialecki
> Assignee: Andrzej Bialecki
> Attachments: ParseFilters.java, segmentparts.patch
>
>
> In many situations it is necessary to store more data associated with pages
> than it's possible now with the current segment format. Quite often it's a
> binary data. There are two common workarounds for this: one is to use
> per-page metadata, either in Content or ParseData, the other is to use an
> external independent database using page ID-s as foreign keys.
> Currently segments can consist of the following predefined parts: content,
> crawl_fetch, crawl_generate, crawl_parse, parse_text and parse_data. I
> propose a third option, which is a natural extension of this existing segment
> format, i.e. to introduce the ability to add arbitrarily named segment
> "parts", with the only requirement that they should be MapFile-s that store
> Writable keys and values. Alternatively, we could define a
> SegmentPart.Writer/Reader to accommodate even more sophisticated scenarios.
> Existing segment API and searcher API (NutchBean, DistributedSearch
> Client/Server) should be extended to handle such arbitrary parts.
> Example applications:
> * storing HTML previews of non-HTML pages, such as PDF, PS and Office
> documents
> * storing pre-tokenized version of plain text for faster snippet generation
> * storing linguistically tagged text for sophisticated data mining
> * storing image thumbnails
> etc, etc ...
> I'm going to prepare a patchset shortly. Any comments and suggestions are
> welcome.
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