wterl/README.md

wterl is an Erlang interface to the WiredTiger database, and is written to support a Riak storage backend that uses WiredTiger.

This backend currently supports only key-value storage and retrieval.

Remaining work includes:

• The wterl:session_create function currently returns an error under certain circumstances, so we currently ignore its return value.
• The riak_kv_wterl_backend module is currently designed to rely on the fact that it runs in just a single Erlang scheduler thread, which is necessary because WiredTiger doesn't allow a session to be used concurrently by different threads. If the KV node design ever changes to involve concurrency across scheduler threads, this current design will no longer work correctly.
• Currently the riak_kv_wterl_backend module is stored in this repository, but it really belongs in the riak_kv repository.
• There are currently some stability issues with WiredTiger that can sometimes cause errors when restarting KV nodes with non-empty WiredTiger storage.

Future support for secondary indexes requires WiredTiger features that are under development but are not yet available.

Deploying

You can deploy wterl into a Riak devrel cluster using the enable-wterl script. Clone the riak repo, change your working directory to it, and then execute the enable-wterl script. It adds wterl as a dependency, runs make all devrel, and then modifies the configuration settings of the resulting dev nodes to use the WiredTiger storage backend.