[ https://issues.apache.org/jira/browse/NUTCH-2481?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Semyon Semyonov updated NUTCH-2481: ----------------------------------- Component/s: (was: generator) > HostDatum deltas(previous step statistics) and Metadata expressions > ------------------------------------------------------------------- > > Key: NUTCH-2481 > URL: https://issues.apache.org/jira/browse/NUTCH-2481 > Project: Nutch > Issue Type: Improvement > Components: hostdb > Reporter: Semyon Semyonov > Priority: Minor > > To allow the usage of previous step statistics(deltas of fetched,unfetced > etc) in hostdb. The motivation is usage of this statistics in generate with > maxCount expressions. > > The solution allows to fill in metadata of hostdatum based on custom JEXL > expression using two hostdatum: before update(previousHostDatum) and after > update(currentHostDatum).. > For example to fill in difference in quantity of fetched at round t and t-1 > we can use the following expression > <property> > <name>hostdb.deltaExpression</name> > <value>\{return new ("javafx.util.Pair","FetchedDelta", > currentHostDatum.fetched - previousHostDatum.fetched);}</value> > </property> > A pull request will be provided shortly. -- This message was sent by Atlassian JIRA (v7.6.3#76005)