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
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.
