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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-3003) Trunk single-pass streaming doesn't handle large row correctly
Date Mon, 08 Aug 2011 19:56:26 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-3003?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sylvain Lebresne updated CASSANDRA-3003:
----------------------------------------

    Priority: Critical  (was: Major)

Marking critical, because at least for counter column family, when the row is larger than
the inMemoryLimit, the code will actually crash because it will use lazilyCompactedRow which
will try to do it's 2 passes.

> Trunk single-pass streaming doesn't handle large row correctly
> --------------------------------------------------------------
>
>                 Key: CASSANDRA-3003
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3003
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Sylvain Lebresne
>            Assignee: Yuki Morishita
>            Priority: Critical
>              Labels: streaming
>
> For normal column family, trunk streaming always buffer the whole row into memory. In
uses
> {noformat}
>   ColumnFamily.serializer().deserializeColumns(in, cf, true, true);
> {noformat}
> on the input bytes.
> We must avoid this for rows that don't fit in the inMemoryLimit.
> Note that for regular column families, for a given row, there is actually no need to
even recreate the bloom filter of column index, nor to deserialize the columns. It is enough
to filter the key and row size to feed the index writer, but then simply dump the rest on
disk directly. This would make streaming more efficient, avoid a lot of object creation and
avoid the pitfall of big rows.
> Counters column family are unfortunately trickier, because each column needs to be deserialized
(to mark them as 'fromRemote'). However, we don't need to do the double pass of LazilyCompactedRow
for that. We can simply use a SSTableIdentityIterator and deserialize/reserialize input as
it comes.

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