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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ACCUMULO-2175) Batch defining tablets in walog
Date Sat, 04 Apr 2015 02:46:33 GMT

     [ https://issues.apache.org/jira/browse/ACCUMULO-2175?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Josh Elser updated ACCUMULO-2175:
---------------------------------
    Fix Version/s:     (was: 1.7.0)
                   1.8.0

> Batch defining tablets in walog
> -------------------------------
>
>                 Key: ACCUMULO-2175
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2175
>             Project: Accumulo
>          Issue Type: Improvement
>            Reporter: Keith Turner
>             Fix For: 1.8.0
>
>
> If a batch of mutations comes into a tablet server AND the tablet server just got a new
walog then it will sync the walog for each tablet.  Below is a sketch of what the tablet server
currently does.
> {code:java}
> foreach(Tablet t : tabletsInMutationBatch){
>     if(!tabletIsDefinedInWalog(t, currentWalog)){
>         defineTablet(currentWalog, t); //syncs walog
>         addWalogToMetadataTable(currentWalog, t); //syncronous metadata table update
>      }
> }
> {code}
> Seems like doing the following would be better.  Then  no matter how many undefined tablets
there are, only one walog sync would be done.
> {code:java}
> foreach(Tablet t : tabletsInMutationBatch){
>     Set<Tablet> undefined = new HashSet<Tablet>();
>     if(!tabletIsDefinedInWalog(t, currentWalog)){
>         undefined.add(t);
>      }
> }
> defineTablets(currentWalog, undefined); //syncs walog after writing all definitions
> addWalogToMetadataTable(currentWalog, undefined); //syncronous metadata table batch write
> {code}
> There is not problem when all tablets in a batch update are defined in the walog. In
this case a batch update that contains multiple tablet will only sync the log once after adding
all the mutations from all tablets.
> Noticed this while looking into ACCUMULO-2172



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