Sebastian Nagel created NUTCH-2748:
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Summary: Fetch status gone (redirect exceeded) not to overwrite
existing items in CrawlDb
Key: NUTCH-2748
URL: https://issues.apache.org/jira/browse/NUTCH-2748
Project: Nutch
Issue Type: Bug
Components: crawldb, fetcher
Affects Versions: 1.16
Reporter: Sebastian Nagel
Fix For: 1.17
If fetcher is following redirects and the max. number of redirects in a
redirect chain (http.max.redirect) is reached, fetcher stores a CrawlDatum item
with status "fetch_gone" and protocol status "redir_exceeded". During the next
CrawlDb update the "gone" item will set the status of existing items (including
"db_fetched") with "db_gone". It shouldn't as there has been no fetch of the
final redirect target and indeed nothing is know about it's status. An wrong
db_gone may then cause that a page gets deleted from the search index.
There are two possible solutions:
1. ignore protocol status "redir_exceeded" during CrawlDb update
2. when http.redirect.max is hit the fetcher stores nothing or a redirect
status instead of a fetch_gone
Solution 2. seems easier to implement and it would be possible to make the
behavior configurable:
- store redirect (fetch_redir_temp or fetch_redir_perm)
- store "fetch_gone" (current behavior)
- store nothing, i.e. ignore those redirects - this should be the default as
it's close to the current behavior without the risk to accidentally set
successful fetches to db_gone
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