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From Apache Wiki <>
Subject [Cassandra Wiki] Update of "CassandraLimitations" by JonathanEllis
Date Thu, 21 Mar 2013 12:42:58 GMT
Dear Wiki user,

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The "CassandraLimitations" page has been changed by JonathanEllis:

  == Artifacts of the current code base ==
   * <<Anchor(streaming)>>Cassandra's public API is based on Thrift, which offers
no streaming abilities -- any value written or fetched has to fit in memory.  This is inherent
to Thrift's design and is therefore unlikely to change.  So adding large object support to
Cassandra would need a special API that manually split the large objects up into pieces. A
potential approach is described in  As
a workaround in the meantime, you can manually split files into chunks of whatever size you
are comfortable with -- at least one person is using 64MB -- and making a file correspond
to a row, with the chunks as column values.
- == Obsolete Limitations ==
-  * Prior to version 0.7, Cassandra's compaction code deserialized an entire row (per columnfamily)
at a time.  So all the data from a given columnfamily/key pair had to fit in memory, or 2GB,
whichever was smaller (since the length of the row was serialized as a Java int).
-  * Prior to version 0.7, Thrift would crash Cassandra if you send random or malicious data
to it.  This made exposing the Cassandra port directly to the outside internet a Bad Idea.
-  * Prior to version 0.4, Cassandra did not fsync the commitlog before acking a write.  Most
of the time this is Good Enough when you are writing to multiple replicas since the odds are
slim of all replicas dying before the data actually hits the disk, but the truly paranoid
will want real fsync-before-ack.  This is now an option.

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