Database Reference
In-Depth Information
Hypertable
Hypertable is a Google Bigtable clone, very similar to HBase. It is used at Zvents, where the pro-
ject originated, to write more than one billion cells per day. It can run on a distributed filesystem
such as HFS or the Kosmos File System. Hypertable uses Multi-Version Concurrency Control
(MVCC) to allow user transactions to execute in a private memory space, which are readable by
other clients only once the transaction has committed.
Like Cassandra and other Bigtable derivatives, it uses Bloom filters and commit logs to minimize
disk access and improve performance.
Hypertable is well-suited for analytics applications and processing. Unlike many of the other non-
relational solutions, it is not used frequently to back websites.
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Website
:
http://www.hypertable.org
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Orientation
: Columnar
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Created
: Hypertable was started in February of 2007 at Zvents.
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Implementation language
: C
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Distributed
: Yes
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Open Source
: Yes
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Schema
: Hypertable stores data as a multidimensional table represented as a flat, sorted list
of key-value pairs. The key is essentially the concatenation of four dimension keys (row,
column family, column qualifier, and timestamp).
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Clients
: The primary Thrift API (also used by Cassandra before being replaced by Avro) is
C++, with bindings for Java, Python, Ruby, PHP, Perl, Erlang, Haskell, C#, Perl, and Ocaml.
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Additional features
: Hypertable has its own query language called Hypertable Query Lan-
guage (HQL). HQL is modeled on SQL, so you can express queries in a familiar manner,
such as
select * from QueryLogByTimestamp WHERE ROW =^ '2010-03-27 17:05';
.
The query here looks a lot like SQL, but includes a modified syntax. For example, the
^=
operator means “starts with.”
Like Voldemort and Cassandra (before Avro, at least), Hypertable uses the Thrift API for client
serialization.
Polyglot Persistence
The different styles of persistence that we've toured in this chapter highlight one fact: each of
them is good at solving a particular problem, or has particular strengths where the others don't.
