[jira] [Resolved] (ACCUMULO-2175) Batch defining tablets in walog

["Keith Turner (JIRA)" <ji...@apache.org>]

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

Keith Turner resolved ACCUMULO-2175.
------------------------------------
    Resolution: Duplicate

https://github.com/apache/accumulo/issues/1118

> 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
>            Priority: Major
>             Fix For: 2.0.0
>
>
> 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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