hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Kannan Muthukkaruppan (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HBASE-2283) row level atomicity
Date Thu, 18 Mar 2010 00:50:27 GMT

     [ https://issues.apache.org/jira/browse/HBASE-2283?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kannan Muthukkaruppan updated HBASE-2283:
-----------------------------------------

    Attachment: rowLevelAtomicity_2283_v3.patch

A small one line improvement to v2 patch based on internal feedback. The change makes it so
that if someone reuses an instance of WALEdit across multiple calls to the sequence file reader,
the readFields() method cleans out any  old state of the object cleanly.

> row level atomicity 
> --------------------
>
>                 Key: HBASE-2283
>                 URL: https://issues.apache.org/jira/browse/HBASE-2283
>             Project: Hadoop HBase
>          Issue Type: Bug
>            Reporter: Kannan Muthukkaruppan
>            Priority: Blocker
>             Fix For: 0.20.4, 0.21.0
>
>         Attachments: rowLevelAtomicity_2283_v1.patch, rowLevelAtomicity_2283_v2.patch,
rowLevelAtomicity_2283_v3.patch
>
>
> The flow during a HRegionServer.put() seems to be the following. [For now, let's just
consider single row Put containing edits to multiple column families/columns.]
> HRegionServer.put() does a:
>         HRegion.put();
>        syncWal()  (the HDFS sync call).  /* this is assuming we have HDFS-200 */
> HRegion.put() does a:
>   for each column family 
>   {
>       HLog.append(all edits to the colum family);
>       write all edits to Memstore;
>   }
> HLog.append() does a :
>   foreach edit in a single column family {
>     doWrite()
>   }
> doWrite() does a:
>    this.writer.append().
> There seems to be two related issues here that could result in inconsistencies.
> Issue #1: A put() does a bunch of HLog.append() calls. These in turn do a bunch of "write"
calls on the underlying DFS stream.  If we crash after having written out some append's to
DFS, recovery will run and apply a partial transaction to memstore.  
> Issue #2: The updates to memstore  should happen after the sync rather than before. Otherwise,
there is the danger that the write to DFS (sync) fails for some reason & we return an
error to the client, but we have already taken edits to the memstore. So subsequent reads
will serve uncommitted data.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message