31 lines
1.7 KiB
Markdown
31 lines
1.7 KiB
Markdown
# Hanoi Key/Value Storage Engine
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This Erlang-based storage engine implements a structure somewhat like LSM-trees (Log-Structured Merge Trees, see docs/10.1.1.44.2782.pdf). The notes below describe how this storage engine work; I have not done extensive studies as how it differs from other storage mechanisms, but a brief brows through available online resources on LSM-trees indicates that this storage engine is quite different in several respects.
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The storage engine can function as an alternative backend for Basho's Riak/KV.
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Here's the bullet list:
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- Very fast writes and deletes,
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- Reasonably fast reads (N records are stored in log<sub>2</sub>(N) B-trees),
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- Operations-friendly "append-only" storage (allows you to backup live system, and crash-recovery is very simple)
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- The cost of evicting stale key/values is amortized into insertion, so you don't need to schedule merge to happen at off-peak hours.
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- Supports range queries (and thus eventually Riak 2i.)
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- Doesn't need a boat load of RAM
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- All in 1000 lines of pure Erlang code
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Once we're a bit more stable, we'll provide a Riak backend.
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### Deploying the hanoi for testing with Riak/KV
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You can deploy `hanoi` into a Riak devrel cluster using the
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`enable-hanoi` script. Clone the `riak` repo, change your working directory
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to it, and then execute the `enable-hanoi` script. It adds `hanoi` as a
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dependency, runs `make all devrel`, and then modifies the configuration
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settings of the resulting dev nodes to use the hanoi storage backend.
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1. `git clone git://github.com/basho/riak.git`
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1. `cd riak/deps`
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1. `git clone git://github.com/basho/hanoi.git`
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1. `cd ..`
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1. `./deps/hanoi/enable-hanoi` # which does `make all devrel`
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