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https://issues.apache.org/jira/browse/NUTCH-2793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17130918#comment-17130918
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ASF GitHub Bot commented on NUTCH-2793:
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sebastian-nagel commented on a change in pull request #534:
URL: https://github.com/apache/nutch/pull/534#discussion_r438267053
##########
File path: src/plugin/indexer-csv/README.md
##########
@@ -39,4 +39,4 @@ escapechar | Escape character used to escape a quote
character | "
maxfieldlength | Max. length of a single field value in characters | 4096
maxfieldvalues | Max. number of values of one field, useful for, e.g., the
anchor texts field | 12
header | Write CSV column headers | true
-outpath | Output path / directory (local filesystem path, relative to current
working directory) | csvindexwriter
\ No newline at end of file
+outpath | Output path / directory (local filesystem path, relative to current
working directory) | csvindexwriter
Review comment:
Sorry, I've mixed two points mixed together:
- the description would also need a change as it will not be a path on the
local filesystem if running in distributed mode
- there is also the open question how to allow two index writers writing
output the filesystem:
- in local mode this would require that the `outpath` points to a
different directory
- in distributed mode we could use `outpath` to write into distinct output
directories or distinct subdirectories of one job-specific output directory
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> CSV indexer does not work in distributed mode
> ---------------------------------------------
>
> Key: NUTCH-2793
> URL: https://issues.apache.org/jira/browse/NUTCH-2793
> Project: Nutch
> Issue Type: Improvement
> Components: indexer, plugin
> Affects Versions: 1.17
> Reporter: Patrick Mézard
> Priority: Major
> Fix For: 1.18
>
>
> Reasons are discussed in
> https://issues.apache.org/jira/browse/NUTCH-1541?focusedCommentId=13797768&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-13797768
> and following comments.
> To summarize, the indexer interface is not aware of tasks so it cannot
> generate unique output name per reducers.
> But it seems achievable because IndexWriters initialize each writer with
> calls to 2 open functions:
> * One passing the general configuration and a "name"
> * The second to pass indexer parameters
> [https://github.com/apache/nutch/blob/master/src/java/org/apache/nutch/indexer/IndexWriters.java#L214]
> Fortunately, "name" is generated by calling getUniqueFile which does exactly
> what we want:
> [https://github.com/apache/nutch/blob/master/src/java/org/apache/nutch/indexer/IndexerOutputFormat.java#L43]
> I propose we use it instead of "nutch.csv" as CSVIndexWriter output file
> name. This is a breaking change because it modifies the output name but
> allows the indexer to work in distributed mode.
> PR will follow the ticket creation.
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