[jira] [Commented] (NUTCH-2750) improve CrawlDbReader & LinkDbReader reader handling

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[jira] [Commented] (NUTCH-2750) improve CrawlDbReader & LinkDbReader reader handling

David Eric Pugh (Jira)

    [ https://issues.apache.org/jira/browse/NUTCH-2750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16970764#comment-16970764 ]

ASF GitHub Bot commented on NUTCH-2750:

sebastian-nagel commented on issue #483: Fix for NUTCH-2750
URL: https://github.com/apache/nutch/pull/483#issuecomment-552085300
   Hi @sju,
   I've verified that the readers are refreshed if the CrawlDb has changed - tested in local mode on a local file and in distributed mode with a CrawlDb on HDFS.
   Will commit soon. Thanks!
   Actually, I'm really impressed how fast look-ups are once the readers are initialized: I've got 20 look-ups per second on a CrawlDb containing 1 billion records in 200 partitions hold on HDFS. That's pretty fast given that it's not a "hot" index but only files on HDFS. Opened [NUTCH-2753](https://issues.apache.org/jira/browse/NUTCH-2753) to add this great option to the command-line help of readdb/readlinkdb.
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> improve CrawlDbReader & LinkDbReader reader handling
> ----------------------------------------------------
>                 Key: NUTCH-2750
>                 URL: https://issues.apache.org/jira/browse/NUTCH-2750
>             Project: Nutch
>          Issue Type: Improvement
>          Components: crawldb, linkdb
>    Affects Versions: 1.16
>            Reporter: Jurian Broertjes
>            Priority: Minor
> The current implementation in the CrawlDbReader re-opens readers for every URL. This is not very efficient. I've implemented a modification time check that only re-opens readers on updated crawlDB.
>  PR: https://github.com/apache/nutch/pull/483

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