Start with a more rational default configuration. (Before you ask... the

answer is 'no').  So far there has been no effort to validate that these
settings are in fact the best for Riak/KV or CS data access patterns.  These
particular settings are, at best, an educated guess based on past experience,
the docs and reading about the benchmark the WiredTiger team published here:

https://github.com/wiredtiger/wiredtiger/wiki/YCSB-Mapkeeper-benchmark

src/riak_kv_wterl_backend.erl

@@ -99,11 +99,30 @@ start(Partition, Config) ->
             case AppStart of
                 ok ->
                     ok = filelib:ensure_dir(filename:join(DataRoot, "x")),
-                    case wterl_conn:open(DataRoot, Config) of
+                    ConnectionOpts = [Config,
+				      {create, true},
+				      {logging, true},
+				      {transactional, true},
+				      {direct_io, ["data", "log"]},
+				      {session_max, 128},
+				      {cache_size, "2GB"},
+				      {sync, false},
+				      {verbose,
+				       ["block", "shared_cache", "ckpt", "evict",
+					"evictserver", "fileops", "hazard", "lsm",
+					"mutex", "read", "readserver", "reconcile",
+					"salvage", "verify", "write"]}],
+                    case wterl_conn:open(DataRoot, ConnectionOpts) of
                         {ok, ConnRef} ->
                             Table = "table:wt" ++ integer_to_list(Partition),
-                            {ok, SRef} = wterl:session_open(ConnRef),
-                            ok = wterl:session_create(SRef, Table),
+                            SessionOpenOpts = [{isolation, "snapshot"}],
+                            {ok, SRef} = wterl:session_open(ConnRef, wterl:config_to_bin(SessionOpenOpts)),
+                            SessionOpts = [%TODO {block_compressor, "snappy"},
+                                           {internal_page_max, "128K"},
+                                           {leaf_page_max, "128K"},
+                                           {lsm_chunk_size, "200MB"},
+                                           {lsm_bloom_config, [{leaf_page_max, "10MB"}]} ],
+                            ok = wterl:session_create(SRef, Table, wterl:config_to_bin(SessionOpts)),
                             {ok, #state{conn=ConnRef,
                                         table=Table,
                                         session=SRef,

src/wterl.erl

@@ -46,6 +46,7 @@
          session_drop/3,
          session_get/3,
          session_open/1,
+         session_open/2,
          session_put/4,
          session_rename/3,
          session_rename/4,
@@ -57,6 +58,7 @@
          session_upgrade/3,
          session_verify/2,
          session_verify/3,
+         config_value/3,
          config_to_bin/1,
          fold_keys/3,
          fold/3]).
@@ -78,7 +80,7 @@
 -type key() :: binary().
 -type value() :: binary().
 
--export_type([connection/0, session/0]).
+-export_type([connection/0, session/0, cursor/0]).
 
 -on_load(init/0).
 
@@ -109,7 +111,11 @@ conn_close(_ConnRef) ->
     ?nif_stub.
 
 -spec session_open(connection()) -> {ok, session()} | {error, term()}.
-session_open(_ConnRef) ->
+session_open(ConnRef) ->
+    session_open(ConnRef, ?EMPTY_CONFIG).
+
+-spec session_open(connection(), config()) -> {ok, session()} | {error, term()}.
+session_open(_ConnRef, _Config) ->
     ?nif_stub.
 
 -spec session_close(session()) -> ok | {error, term()}.
@@ -264,8 +270,10 @@ fold(Cursor, Fun, Acc, {ok, Key, Value}) ->
 %% Configuration type information.
 %%
 config_types() ->
-    [{cache_size, string},
+    [{block_compressor, string},
+     {cache_size, string},
      {create, bool},
+     {direct_io, map},
      {drop, list},
      {error_prefix, string},
      {eviction_target, integer},
@@ -275,13 +283,23 @@ config_types() ->
      {hazard_max, integer},
      {home_environment, bool},
      {home_environment_priv, bool},
+     {internal_page_max, string},
+     {isolation, string},
+     {key_type, string},
+     {leaf_page_max, string},
      {logging, bool},
+     {lsm_bloom_config, config},
+     {lsm_chunk_size, string},
      {multiprocess, bool},
      {name, string},
      {session_max, integer},
+     {sync, bool},
      {target, list},
      {transactional, bool},
-     {verbose, string}].
+     {verbose, map}].
+
+config_value(Key, Config, Default) ->
+    {Key, app_helper:get_prop_or_env(Key, Config, wterl, Default)}.
 
 config_encode(integer, Value) ->
     try
@@ -290,8 +308,12 @@ config_encode(integer, Value) ->
         _:_ ->
             invalid
     end;
+config_encode(config, Value) ->
+    list_to_binary(["(", config_to_bin(Value, []), ")"]);
 config_encode(list, Value) ->
     list_to_binary(["(", string:join(Value, ","), ")"]);
+config_encode(map, Value) ->
+    list_to_binary(["[", string:join(Value, ","), "]"]);
 config_encode(string, Value) ->
     list_to_binary(Value);
 config_encode(bool, true) ->
@@ -303,9 +325,9 @@ config_encode(_Type, _Value) ->
 
 -spec config_to_bin(config_list()) -> config().
 config_to_bin(Opts) ->
-    config_to_bin(Opts, []).
+    iolist_to_binary([config_to_bin(Opts, []), <<"\0">>]).
 config_to_bin([], Acc) ->
-    iolist_to_binary([Acc, ?EMPTY_CONFIG]);
+    iolist_to_binary(Acc);
 config_to_bin([{Key, Value} | Rest], Acc) ->
     case lists:keysearch(Key, 1, config_types()) of
         {value, {Key, Type}} ->