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piccolbo edited this page Feb 22, 2012 · 38 revisions


rmr 1.2 (release branch)

  • Binary formats
  • Simpler, more powerful I/O format API
  • Native binary format with support for all R data types
  • Worked around an R bug that made large reduces very slow.
  • Backend specific parameters to modify things like number of reducers at the hadoop level
  • Automatic library loading in mappers and reducers
  • Better data frame conversions
  • Adopted a uniform.naming.convention
  • New package options API

See rmr v1.2 overview for details

rmr 1.1 (master branch)

  • Native R serialization/deserialization, which implies that all R objects are supported as key and value, without any conversion boilerplate code. This is the new default. JSON still supported. csv reader/writer also available -- somewhat experimental.
  • Multiple backends (hadoop and local); local backend is useful for debugging at small scale; having two backends enforces modular design, opens up further possibilities (rjava, Amazon's EMR, OpenCL have been suggested), forces to clarify semantics.
  • Multiple tests of backend equivalence.
  • Simpler interface for profiler.
  • Equijoins (rough equivalent of merge for mapreduce)
  • dfs.empty to check if file is empty
  •, to.reduce, to.reduce.all higher order functions to create simple map and reduce functions from regular ones.
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