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https://issues.apache.org/jira/browse/CASSANDRA-208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12715554#action_12715554
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Jun Rao commented on CASSANDRA-208:
-----------------------------------
When HBase was using the old format, rows are stored as <key,value> pairs in
MapFile, where a key is rowkey:columnName:timestamp. The keys for every 128
rows are promoted to the row index. The benefit is that it's simple. There is
only a single-level index (compared with row index and column index within a
row in cassandra) and it can be used to efficiently look up a full row, a
column within a row, or a version of a column in a row. On the other hand, if
you make the index dense, the row keys are duplicated for columns within the
same row.
> jvm crashes intermittently during compaction
> --------------------------------------------
>
> Key: CASSANDRA-208
> URL: https://issues.apache.org/jira/browse/CASSANDRA-208
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: trunk
> Environment: arch: x86_64
> os: Linux version 2.6.18-92.1.22.el5
> java: nio2-ea-bin-b99-linux-x64-05_feb_2009
> Reporter: Jiansheng Huang
> Assignee: Jonathan Ellis
> Priority: Critical
> Fix For: 0.3
>
>
> jvm crashes intermittently during compaction. Our test data set is not that
> big, less than 10 GB.
> When jvm is about to crash, we see that it consumes a lot of memory
> (exceeding the max heap size).
> The excessive memory usage during compaction is caused by the maintenance of
> blockIndexes_ in SSTable. this blockIndexes_ was only introduced to the
> apache version.
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