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https://issues.apache.org/jira/browse/NUTCH-1693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13864835#comment-13864835
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Sebastian Nagel commented on NUTCH-1693:
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A useful improvement! Thanks!
{quote}
> both 2x and 1x should provide identical signature impl.
{quote}
Definitely. Falling back to MD5 on raw content for empty documents may be
useful eg. for PDFs with scanned images and no readable textual content: two
binary identical PDFs are then still deduplicated.
Regarding calculation of MD5 from text:
* [patch for trunk] String.getBytes() depends on default encoding / locale. If
it differs eg. for development and production environments this may cause some
headaches. We could either pass a fixed Charset (UTF-8) as parameter to
getBytes(...) or use MD5Hash.digest(String string) which encodes string as
UTF-8 before check-summing
* [patch for 2x] instead of converting an UTF-8-encoded byte array to Java
String and back: MD5Hash.digest(page.getText().getBytes()) may be more efficient
> TextMD5Signatue compute on textual content
> ------------------------------------------
>
> Key: NUTCH-1693
> URL: https://issues.apache.org/jira/browse/NUTCH-1693
> Project: Nutch
> Issue Type: New Feature
> Reporter: Tien Nguyen Manh
> Assignee: Markus Jelsma
> Priority: Minor
> Fix For: 2.3, 1.8
>
> Attachments: NUTCH-1693-trunk.patch, NUTCH-1693.patch
>
>
> I create a new MD5Signature that based on textual content. In our case we use
> boilerpipe to extract main text from content so this signature is more
> effective to deduplicate.
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