The R13B03 release.OTP_R13B03

1 files changed, 1268 insertions, 0 deletions

diff --git a/lib/mnesia/examples/mnesia_tpcb.erl b/lib/mnesia/examples/mnesia_tpcb.erl
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+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 1996-2009. All Rights Reserved.
+%% 
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%
+%% MODULE
+%%
+%%   mnesia_tpcb - TPC-B benchmarking of Mnesia
+%%
+%% DESCRIPTION
+%%
+%%   The metrics used in the TPC-B benchmark are throughput as measured
+%%   in transactions per second (TPS). The benchmark uses a single,
+%%   simple update-intensive transaction to load the database system.
+%%   The single transaction type provides a simple, repeatable
+%%   unit of work, and is designed to exercise the basic components of
+%%   a database system.
+%%
+%%   The definition of the TPC-B states lots of detailed rules and
+%%   conditions that must be fullfilled, e.g. how the ACID (atomicity,
+%%   consistency, isolation and durability) properties are verified,
+%%   how the random numbers must be distributed, minimum sizes of
+%%   the different types of records, minimum duration of the benchmark,
+%%   formulas to calculate prices (dollars per tps), disclosure issues
+%%   etc. Please, see http://www.tpc.org/ about the nitty gritty details.
+%%
+%%   The TPC-B benchmark is stated in terms of a hypothetical bank. The
+%%   bank has one or more branches. Each branch has multiple tellers. The
+%%   bank has many customers, each with an account. The database represents
+%%   the cash position of each entity (branch, teller and account) and a
+%%   history of recent transactions run by the bank. The transaction
+%%   represents the work done when a customer makes a deposit or a
+%%   withdrawal against his account. The transaction is performed by a
+%%   teller at some branch.
+%%
+%%   Each process that performs TPC-B transactions is called a driver.
+%%   Drivers generates teller_id, account_id and delta amount of
+%%   money randomly. An account, a teller and a branch are read, their
+%%   balances are adjusted and a history record is created. The driver
+%%   measures the time for 3 reads, 3 writes and 1 create.
+%%
+%% GETTING STARTED
+%%
+%%   Generate tables and run with default configuration:
+%%
+%%     mnesia_tpcb:start().
+%%
+%%  A little bit more advanced;
+%%
+%%     spawn(mnesia_tpcb, start, [[[{n_drivers_per_node, 8}, {stop_after, infinity}]]),
+%%     mnesia_tpcb:stop().
+%%
+%%  Really advanced;
+%%
+%%    mnesia_tpcb:init(([{n_branches, 8}, {replica_type, disc_only_copies}]),
+%%    mnesia_tpcb:run(([{n_drivers_per_node, 8}]),
+%%    mnesia_tpcb:run(([{n_drivers_per_node, 64}]).
+%%    
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-module(mnesia_tpcb).
+-author('[email protected]').
+
+-export([
+	 config/2,
+	 count_balance/0,
+	 driver_init/2,
+	 init/1,
+	 reporter_init/2,
+	 run/1,
+	 start/0,
+	 start/1,
+	 start/2,
+	 stop/0,
+	 real_trans/5,
+	 verify_tabs/0,
+	 reply_gen_branch/3,
+	 frag_add_delta/7,
+
+	 conflict_test/1,
+	 dist_test/1,
+	 replica_test/1,
+	 sticky_replica_test/1,
+	 remote_test/1,
+	 remote_frag2_test/1
+	]).
+
+-define(SECOND, 1000000).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Account record, total size must be at least 100 bytes
+
+-define(ACCOUNT_FILLER,
+	{123456789012345678901234567890123456789012345678901234567890,
+	 123456789012345678901234567890123456789012345678901234567890,
+	 123456789012345678901234567890123456789012345678901234}).
+
+-record(account,
+       {
+	id           = 0, % Unique account id
+	branch_id    = 0, % Branch where the account is held
+	balance      = 0, % Account balance
+	filler       = ?ACCOUNT_FILLER  % Gap filler to ensure size >= 100 bytes
+       }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Branch record, total size must be at least 100 bytes
+
+-define(BRANCH_FILLER,
+	{123456789012345678901234567890123456789012345678901234567890,
+	 123456789012345678901234567890123456789012345678901234567890,
+	 123456789012345678901234567890123456789012345678901234567890}).
+
+-record(branch,
+       {
+	id           = 0, % Unique branch id
+	balance      = 0, % Total balance of whole branch
+	filler       = ?BRANCH_FILLER  % Gap filler to ensure size >= 100 bytes
+       }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Teller record, total size must be at least 100 bytes
+
+-define(TELLER_FILLER,
+	{123456789012345678901234567890123456789012345678901234567890,
+	 123456789012345678901234567890123456789012345678901234567890,
+	 1234567890123456789012345678901234567890123456789012345678}).
+
+-record(teller,
+       {
+	id           = 0, % Unique teller id
+	branch_id    = 0, % Branch where the teller is located
+	balance      = 0, % Teller balance
+	filler       = ?TELLER_FILLER % Gap filler to ensure size >= 100 bytes
+       }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% History record, total size must be at least 50 bytes
+
+-define(HISTORY_FILLER, 1234567890).
+
+-record(history,
+	{
+	 history_id  = {0, 0}, % {DriverId, DriverLocalHistoryid}
+	 time_stamp  = now(),  % Time point during active transaction
+	 branch_id   = 0,      % Branch associated with teller
+	 teller_id   = 0,      % Teller invlolved in transaction
+	 account_id  = 0,      % Account updated by transaction
+	 amount      = 0,      % Amount (delta) specified by transaction
+	 filler      = ?HISTORY_FILLER % Gap filler to ensure size >= 50 bytes
+       }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-record(tab_config,
+	{
+	  db_nodes = [node()],
+	  n_replicas = 1, % Ignored for non-fragmented tables
+	  replica_nodes = [node()],
+	  replica_type = ram_copies,
+	  use_running_mnesia = false,
+	  n_fragments = 0,
+	  n_branches = 1,
+	  n_tellers_per_branch = 10, % Must be 10
+	  n_accounts_per_branch = 100000, % Must be 100000
+	  branch_filler = ?BRANCH_FILLER,
+	  account_filler = ?ACCOUNT_FILLER,
+	  teller_filler = ?TELLER_FILLER
+	 }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-record(run_config,
+	{
+	  driver_nodes = [node()],
+	  n_drivers_per_node = 1,
+	  use_running_mnesia = false,
+	  stop_after = timer:minutes(15), % Minimum 15 min
+	  report_interval = timer:minutes(1),
+	  use_sticky_locks = false,
+	  spawn_near_branch = false,
+	  activity_type = transaction,
+	  reuse_history_id = false
+	 }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-record(time,
+	{
+	  n_trans = 0,
+	  min_n = 0,
+	  max_n = 0,
+	  acc_time = 0,
+	  max_time = 0
+	 }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-record(driver_state,
+	{
+	  driver_id,
+	  driver_node,
+	  seed,
+	  n_local_branches,
+	  local_branches,
+	  tab_config,
+	  run_config,
+	  history_id,
+	  time = #time{},
+	  acc_time = #time{},
+	  reuse_history_id
+	 }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-record(reporter_state,
+	{
+	  driver_pids,
+	  starter_pid,
+	  n_iters = 0,
+	  prev_tps = 0,
+	  curr = #time{},
+	  acc = #time{},
+	  init_micros,
+	  prev_micros,
+	  run_config
+	 }).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% One driver on each node, table not replicated
+
+config(frag_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote], 
+    [
+     {n_branches, length(Nodes)},
+     {n_fragments, length(Nodes)},
+     {replica_nodes, Nodes},
+     {db_nodes, Nodes},
+     {driver_nodes, Nodes},
+     {n_accounts_per_branch, 100},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% One driver on each node, table replicated to two nodes.
+
+config(frag2_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote], 
+    [
+     {n_branches, length(Nodes)},
+     {n_fragments, length(Nodes)},
+     {n_replicas, 2},
+     {replica_nodes,  Nodes},
+     {db_nodes, Nodes},
+     {driver_nodes, Nodes},
+     {n_accounts_per_branch, 100},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% One driver on this node, table replicated to all nodes.
+
+config(replica_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote], 
+    [
+     {db_nodes, Nodes},
+     {driver_nodes, [Local]},
+     {replica_nodes, Nodes},
+     {n_accounts_per_branch, 100},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% One driver on this node, table replicated to all nodes.
+
+config(sticky_replica_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote], 
+    [
+     {db_nodes, Nodes},
+     {driver_nodes, [node()]},
+     {replica_nodes, Nodes},
+     {n_accounts_per_branch, 100},
+     {replica_type, ReplicaType},
+     {use_sticky_locks, true},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Ten drivers per node, tables replicated to all nodes, lots of branches
+
+config(dist_test, ReplicaType) ->  
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote], 
+    [
+     {db_nodes, Nodes},
+     {driver_nodes, Nodes},
+     {replica_nodes, Nodes},
+     {n_drivers_per_node, 10},
+     {n_branches, 10 * length(Nodes) * 100},
+     {n_accounts_per_branch, 10},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Ten drivers per node, tables replicated to all nodes, single branch
+
+config(conflict_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote], 
+    [
+     {db_nodes, Nodes},
+     {driver_nodes, Nodes},
+     {replica_nodes, Nodes},
+     {n_drivers_per_node, 10},
+     {n_branches, 1},
+     {n_accounts_per_branch, 10},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% One driver on this node, table replicated to all other nodes.
+
+config(remote_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote],
+    [
+     {db_nodes, Nodes},
+     {driver_nodes, [Local]},
+     {replica_nodes, Remote},
+     {n_accounts_per_branch, 100},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ];
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% One driver on this node, table replicated to two other nodes.
+
+config(remote_frag2_test, ReplicaType) ->
+    Remote = nodes(),
+    Local = node(),
+    Nodes = [Local | Remote],
+    [
+     {n_branches, length(Remote)},
+     {n_fragments, length(Remote)},
+     {n_replicas, 2},
+     {replica_nodes, Remote},
+     {db_nodes, Nodes},
+     {driver_nodes, [Local]},
+     {n_accounts_per_branch, 100},
+     {replica_type, ReplicaType},
+     {stop_after, timer:minutes(1)},
+     {report_interval, timer:seconds(10)},
+     {reuse_history_id, true}
+    ].
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+start(What, ReplicaType) ->
+    spawn_link(?MODULE, start, [config(What, ReplicaType)]).
+
+replica_test(ReplicaType) ->
+    start(replica_test, ReplicaType).
+
+sticky_replica_test(ReplicaType) ->
+    start(sticky_replica_test, ReplicaType).
+
+dist_test(ReplicaType) ->
+    start(dist_test, ReplicaType).
+
+conflict_test(ReplicaType) ->
+    start(conflict_test, ReplicaType).
+
+remote_test(ReplicaType) ->
+    start(remote_test, ReplicaType).
+
+remote_frag2_test(ReplicaType) ->
+    start(remote_frag2_test, ReplicaType).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Args is a list of {Key, Val} tuples where Key is a field name
+%% in either the record tab_config or run_config. Unknown keys are ignored.
+
+start() ->
+    start([]).
+start(Args) ->
+    init(Args),
+    run(Args).
+
+list2rec(List, Fields, DefaultTuple) ->
+    [Name|Defaults] = tuple_to_list(DefaultTuple),
+    List2 = list2rec(List, Fields, Defaults, []),
+    list_to_tuple([Name] ++ List2).
+
+list2rec(_List, [], [], Acc) ->
+    Acc;
+list2rec(List, [F|Fields], [D|Defaults], Acc) ->
+    {Val, List2} =
+	case lists:keysearch(F, 1, List) of
+	    false ->
+		{D, List};
+	    {value, {F, NewVal}} ->
+		{NewVal, lists:keydelete(F, 1, List)}
+	end,
+    list2rec(List2, Fields, Defaults, Acc ++ [Val]).
+
+stop() ->
+    case whereis(mnesia_tpcb) of
+	undefined ->
+	    {error, not_running};
+	Pid ->
+	    sync_stop(Pid)
+    end.
+
+sync_stop(Pid) ->
+    Pid ! {self(), stop},
+    receive
+	{Pid, {stopped, Res}} ->  Res
+    after timer:minutes(1) ->
+	    exit(Pid, kill),
+	    {error, brutal_kill}
+    end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Initialization
+
+%% Args is a list of {Key, Val} tuples where Key is a field name
+%% in the record tab_config, unknown keys are ignored.
+
+init(Args) ->
+    TabConfig0 = list2rec(Args, record_info(fields, tab_config), #tab_config{}),
+    TabConfig = 
+	if
+	    TabConfig0#tab_config.n_fragments =:= 0 ->
+		TabConfig0#tab_config{n_replicas = length(TabConfig0#tab_config.replica_nodes)};
+	    true ->
+		TabConfig0	
+	end,
+    Tags = record_info(fields, tab_config),
+    Fun = fun(F, Pos) -> {{F, element(Pos, TabConfig)}, Pos + 1} end,
+    {List, _} = lists:mapfoldl(Fun, 2, Tags),
+    io:format("TPC-B: Table config: ~p ~n", [List]),
+
+    DbNodes = TabConfig#tab_config.db_nodes,
+    stop(),
+    if
+	TabConfig#tab_config.use_running_mnesia =:= true ->
+	    ignore;
+	true ->
+	    rpc:multicall(DbNodes, mnesia, lkill, []),
+	    case mnesia:delete_schema(DbNodes) of
+		ok ->
+		    case mnesia:create_schema(DbNodes) of
+			ok ->
+			    {Replies, BadNodes} =
+				rpc:multicall(DbNodes, mnesia, start, []),
+			    case [Res || Res <- Replies, Res =/= ok] of
+				[] when BadNodes =:= [] ->
+				    ok;
+				BadRes ->
+				    io:format("TPC-B: <ERROR> "
+					      "Failed to start ~p: ~p~n",
+					      [BadNodes, BadRes]),
+				    exit({start_failed, BadRes, BadNodes})
+			    end;
+			{error, Reason} ->
+			    io:format("TPC-B: <ERROR> "
+				      "Failed to create schema on disc: ~p~n",
+				      [Reason]),
+			    exit({create_schema_failed, Reason})
+		    end;
+		{error, Reason} ->
+		    io:format("TPC-B: <ERROR> "
+			      "Failed to delete schema on disc: ~p~n",
+			      [Reason]),
+		    exit({delete_schema_failed, Reason})
+	    end
+    end,
+    gen_tabs(TabConfig).
+
+gen_tabs(TC) ->
+    create_tab(TC, branch, record_info(fields, branch),
+	       undefined),
+    create_tab(TC, account, record_info(fields, account),
+	       {branch, #account.branch_id}),
+    create_tab(TC, teller, record_info(fields, teller),
+	       {branch, #teller.branch_id}),
+    create_tab(TC, history, record_info(fields, history),
+	       {branch, #history.branch_id}),
+
+    NB = TC#tab_config.n_branches,
+    NT = TC#tab_config.n_tellers_per_branch,
+    NA = TC#tab_config.n_accounts_per_branch,
+    io:format("TPC-B: Generating ~p branches a ~p bytes~n",
+	      [NB, size(term_to_binary(default_branch(TC)))]),
+    io:format("TPC-B: Generating ~p * ~p tellers a ~p bytes~n",
+	      [NB, NT, size(term_to_binary(default_teller(TC)))]),
+    io:format("TPC-B: Generating ~p * ~p accounts a ~p bytes~n",
+	      [NB, NA, size(term_to_binary(default_account(TC)))]),
+    io:format("TPC-B: Generating 0 history records a ~p bytes~n",
+	      [size(term_to_binary(default_history(TC)))]),
+    gen_branches(TC),
+
+    case verify_tabs() of
+	ok ->
+	    ignore;
+	{error, Reason} ->
+	    io:format("TPC-B: <ERROR> Inconsistent tables: ~w~n",
+		      [Reason]),
+	    exit({inconsistent_tables, Reason})
+    end.
+
+create_tab(TC, Name, Attrs, _ForeignKey) when TC#tab_config.n_fragments =:= 0 ->
+    Nodes = TC#tab_config.replica_nodes,
+    Type = TC#tab_config.replica_type,
+    Def = [{Type, Nodes}, {attributes, Attrs}],
+    create_tab(Name, Def);
+create_tab(TC, Name, Attrs, ForeignKey) ->
+    NReplicas = TC#tab_config.n_replicas,
+    NodePool = TC#tab_config.replica_nodes,
+    Type = TC#tab_config.replica_type,
+    NF = TC#tab_config.n_fragments,
+    Props = [{n_fragments, NF},
+	     {node_pool, NodePool},
+	     {n_copies(Type), NReplicas},
+	     {foreign_key, ForeignKey}],
+    Def = [{frag_properties, Props},
+	   {attributes, Attrs}],
+    create_tab(Name, Def).
+    
+create_tab(Name, Def) ->
+    mnesia:delete_table(Name),
+    case mnesia:create_table(Name, Def) of
+	{atomic, ok} ->
+	    ok;
+	{aborted, Reason} ->
+	    io:format("TPC-B: <ERROR> failed to create table ~w ~w: ~p~n",
+		      [Name, Def, Reason]),
+	    exit({create_table_failed, Reason})
+    end.
+
+n_copies(Type) ->
+    case Type of
+	ram_copies -> n_ram_copies;
+	disc_copies -> n_disc_copies;
+	disc_only_copies -> n_disc_only_copies
+    end.
+
+gen_branches(TC) ->
+    First = 0,
+    Last = First + TC#tab_config.n_branches - 1,
+    GenPids = gen_branches(TC, First, Last, []),
+    wait_for_gen(GenPids).
+
+wait_for_gen([]) ->
+    ok;
+wait_for_gen(Pids) ->
+    receive
+	{branch_generated, Pid} -> wait_for_gen(lists:delete(Pid, Pids));
+	Exit ->
+	    exit({tpcb_failed, Exit})
+    end.
+
+gen_branches(TC, BranchId, Last, UsedNs) when BranchId =< Last ->
+    UsedNs2 = get_branch_nodes(BranchId, UsedNs),
+    Node = hd(UsedNs2),
+    Pid = spawn_link(Node, ?MODULE, reply_gen_branch,
+		     [self(), TC, BranchId]),
+    [Pid | gen_branches(TC, BranchId + 1, Last, UsedNs2)];
+gen_branches(_, _, _, _) ->
+    [].
+
+reply_gen_branch(ReplyTo, TC, BranchId) ->
+    gen_branch(TC, BranchId),
+    ReplyTo ! {branch_generated, self()},
+    unlink(ReplyTo).
+
+%% Returns a new list of nodes with the best node as head
+get_branch_nodes(BranchId, UsedNs) ->
+    WriteNs = table_info({branch, BranchId}, where_to_write),
+    WeightedNs = [{n_duplicates(N, UsedNs, 0), N} || N <- WriteNs],
+    [{_, LeastUsed} | _ ] = lists:sort(WeightedNs),
+    [LeastUsed | UsedNs].
+
+n_duplicates(_N, [], Count) ->
+    Count;
+n_duplicates(N, [N | Tail], Count) ->    
+    n_duplicates(N, Tail, Count + 1);
+n_duplicates(N, [_ | Tail], Count) ->
+    n_duplicates(N, Tail, Count).
+
+gen_branch(TC, BranchId) ->
+    A = default_account(TC),
+    NA = TC#tab_config.n_accounts_per_branch,
+    FirstA = BranchId * NA,
+    ArgsA = [FirstA, FirstA + NA - 1, BranchId, A],
+    ok = mnesia:activity(async_dirty, fun gen_accounts/4, ArgsA, mnesia_frag),
+
+    T = default_teller(TC),
+    NT = TC#tab_config.n_tellers_per_branch,
+    FirstT = BranchId * NT,
+    ArgsT = [FirstT, FirstT + NT - 1, BranchId, T],
+    ok = mnesia:activity(async_dirty, fun gen_tellers/4, ArgsT, mnesia_frag),
+
+    B = default_branch(TC),
+    FunB = fun() -> mnesia:write(branch, B#branch{id = BranchId}, write) end,
+    ok = mnesia:activity(sync_dirty,  FunB, [], mnesia_frag).
+    
+gen_tellers(Id, Last, BranchId, T) when Id =< Last ->
+    mnesia:write(teller, T#teller{id = Id, branch_id=BranchId}, write),
+    gen_tellers(Id + 1, Last, BranchId, T);
+gen_tellers(_, _, _, _) ->
+    ok.
+    
+gen_accounts(Id, Last, BranchId, A) when Id =< Last ->
+    mnesia:write(account, A#account{id = Id, branch_id=BranchId}, write),
+    gen_accounts(Id + 1, Last, BranchId, A);
+gen_accounts(_, _, _, _) ->
+    ok.
+
+default_branch(TC) ->  #branch{filler = TC#tab_config.branch_filler}.
+default_teller(TC) ->  #teller{filler = TC#tab_config.teller_filler}.
+default_account(TC) -> #account{filler = TC#tab_config.account_filler}.
+default_history(_TC) -> #history{}.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%% Run the benchmark
+
+%% Args is a list of {Key, Val} tuples where Key is a field name
+%% in the record run_config, unknown keys are ignored.
+run(Args) ->
+    RunConfig = list2rec(Args, record_info(fields, run_config), #run_config{}),
+    Tags = record_info(fields, run_config),
+    Fun = fun(F, Pos) -> {{F, element(Pos, RunConfig)}, Pos + 1} end,
+    {List, _} = lists:mapfoldl(Fun, 2, Tags),
+    io:format("TPC-B: Run config: ~p ~n", [List]),
+
+    Pid = spawn_link(?MODULE, reporter_init, [self(), RunConfig]),
+    receive
+	{Pid, {stopped, Res}} ->
+	    Res; % Stopped by other process
+	Else ->
+	    {tpcb_got, Else}   
+    after RunConfig#run_config.stop_after ->
+	    sync_stop(Pid)
+    end.
+
+reporter_init(Starter, RC) ->
+    register(mnesia_tpcb, self()),
+    process_flag(trap_exit, true),
+    DbNodes = mnesia:system_info(db_nodes),
+    if
+	RC#run_config.use_running_mnesia =:= true ->
+	    ignore;
+	true ->
+	    {Replies, BadNodes} =
+		rpc:multicall(DbNodes, mnesia, start, []),
+	    case [Res || Res <- Replies, Res =/= ok] of
+		[] when BadNodes =:= [] ->
+		    ok;
+		BadRes ->
+		    io:format("TPC-B: <ERROR> "
+			      "Failed to start ~w: ~p~n",
+			      [BadNodes, BadRes]),
+		    exit({start_failed, BadRes, BadNodes})
+	    end,
+	    verify_tabs()
+    end,
+
+    N  = table_info(branch, size),
+    NT = table_info(teller, size) div N,
+    NA = table_info(account, size) div N,
+
+    {Type, NF, RepNodes} = table_storage(branch),
+    TC = #tab_config{n_fragments = NF,
+		     n_branches = N,
+		     n_tellers_per_branch = NT,
+		     n_accounts_per_branch = NA,
+		     db_nodes = DbNodes,
+		     replica_nodes = RepNodes,
+		     replica_type = Type
+		    },
+    Drivers = start_drivers(RC, TC),
+    Now = now_to_micros(erlang:now()),
+    State = #reporter_state{driver_pids = Drivers,
+			    run_config = RC,
+			    starter_pid = Starter,
+			    init_micros = Now,
+			    prev_micros = Now
+			   },
+    case catch reporter_loop(State) of
+	{'EXIT', Reason} ->
+	    io:format("TPC-B: Abnormal termination: ~p~n", [Reason]),
+	    if
+		RC#run_config.use_running_mnesia =:= true ->
+		    ignore;
+		true ->
+		    rpc:multicall(DbNodes, mnesia, lkill, [])
+	    end,
+	    unlink(Starter),
+	    Starter ! {self(), {stopped, {error, Reason}}}, % To be sure
+	    exit(shutdown);
+	{ok, Stopper, State2} ->
+	    Time = State2#reporter_state.acc,
+	    Res =
+		case verify_tabs() of
+		    ok ->
+			{ok, Time};
+		    {error, Reason} ->
+			io:format("TPC-B: <ERROR> Inconsistent tables, ~p~n",
+				  [{error, Reason}]),
+			{error, Reason}
+		end,
+	    if
+		RC#run_config.use_running_mnesia =:= true -> 
+		    ignore;
+		true -> 
+		    rpc:multicall(DbNodes, mnesia, stop, [])
+	    end,
+	    unlink(Starter),
+	    Starter ! {self(), {stopped, Res}},
+	    if
+		Stopper =/= Starter ->
+		    Stopper ! {self(), {stopped, Res}};
+		true ->
+		    ignore
+	    end,
+	    exit(shutdown)
+    end.
+
+table_info(Tab, Item) ->
+    Fun = fun() -> mnesia:table_info(Tab, Item) end,
+    mnesia:activity(sync_dirty, Fun, mnesia_frag).
+
+%% Returns {Storage, NFragments, ReplicaNodes}
+table_storage(Tab) ->
+    case mnesia:table_info(branch, frag_properties) of
+	[] ->
+	    NFO = 0,
+	    NR  = length(mnesia:table_info(Tab, ram_copies)),
+	    ND  = length(mnesia:table_info(Tab, disc_copies)),
+	    NDO = length(mnesia:table_info(Tab, disc_only_copies)),
+	    if
+		NR  =/= 0 -> {ram_copies, NFO, NR};
+		ND  =/= 0 -> {disc_copies, NFO, ND};
+		NDO =/= 0 -> {disc_copies, NFO, NDO}
+	    end;
+	Props ->
+	    {value, NFO} = lists:keysearch(n_fragments, 1, Props),
+	    NR  = table_info(Tab, n_ram_copies),
+	    ND  = table_info(Tab, n_disc_copies),
+	    NDO = table_info(Tab, n_disc_only_copies),
+	    if
+		NR  =/= 0 -> {ram_copies, NFO, NR};
+		ND  =/= 0 -> {disc_copies, NFO, ND};
+		NDO =/= 0 -> {disc_copies, NFO, NDO}
+	    end
+    end.
+    
+reporter_loop(State) ->
+    RC = State#reporter_state.run_config,
+    receive
+	{From, stop} ->
+	    {ok, From, call_drivers(State, stop)};
+	{'EXIT', Pid, Reason} when Pid =:= State#reporter_state.starter_pid ->
+	    %% call_drivers(State, stop),
+	    exit({starter_died, Pid, Reason})
+    after RC#run_config.report_interval ->
+	    Iters = State#reporter_state.n_iters,
+	    State2 = State#reporter_state{n_iters = Iters + 1},
+	    case call_drivers(State2, report) of
+		State3 when State3#reporter_state.driver_pids =/= [] ->
+		    State4 = State3#reporter_state{curr = #time{}},
+		    reporter_loop(State4);
+		_ ->
+		    exit(drivers_died)
+	    end
+    end.
+
+call_drivers(State, Msg) ->
+    Drivers = State#reporter_state.driver_pids,
+    lists:foreach(fun(Pid) -> Pid ! {self(), Msg} end, Drivers),
+    State2 = show_report(calc_reports(Drivers, State)),
+    case Msg =:= stop of
+	true ->
+	    Acc = State2#reporter_state.acc,
+	    Init = State2#reporter_state.init_micros,
+	    show_report(State2#reporter_state{n_iters = 0,
+					      curr = Acc,
+					      prev_micros = Init});
+	false ->
+	    ignore
+    end,
+    State2.
+
+calc_reports([], State) ->
+    State;
+calc_reports([Pid|Drivers], State) ->
+    receive
+	{'EXIT', P, Reason} when P =:= State#reporter_state.starter_pid ->
+	    exit({starter_died, P, Reason});
+	{'EXIT', Pid, Reason} ->
+	    exit({driver_died, Pid, Reason});
+	{Pid, Time} when is_record(Time, time) ->
+	    %% io:format("~w: ~w~n", [Pid, Time]),
+	    A = add_time(State#reporter_state.acc, Time),
+	    C = add_time(State#reporter_state.curr, Time),
+	    State2 = State#reporter_state{acc = A, curr = C},
+	    calc_reports(Drivers, State2)
+    end.
+
+add_time(Acc, New) ->
+    Acc#time{n_trans = New#time.n_trans + Acc#time.n_trans,
+	     min_n = lists:min([New#time.n_trans, Acc#time.min_n] -- [0]),
+	     max_n = lists:max([New#time.n_trans, Acc#time.max_n]),
+	     acc_time = New#time.acc_time + Acc#time.acc_time,
+	     max_time = lists:max([New#time.max_time, Acc#time.max_time])}.
+
+-define(AVOID_DIV_ZERO(_What_), try (_What_) catch _:_ -> 0 end).
+
+show_report(State) ->
+    Now    = now_to_micros(erlang:now()),
+    Iters  = State#reporter_state.n_iters,
+    Time   = State#reporter_state.curr,
+    Max    = Time#time.max_time,
+    N      = Time#time.n_trans,
+    Avg    = ?AVOID_DIV_ZERO(Time#time.acc_time div N),
+    AliveN = length(State#reporter_state.driver_pids),
+    Tps    = ?AVOID_DIV_ZERO((?SECOND * AliveN) div Avg),
+    PrevTps= State#reporter_state.prev_tps,
+    {DiffSign, DiffTps} = signed_diff(Iters, Tps, PrevTps),
+    Unfairness = ?AVOID_DIV_ZERO(Time#time.max_n / Time#time.min_n),
+    BruttoAvg = ?AVOID_DIV_ZERO((Now - State#reporter_state.prev_micros) div N),
+%%    io:format("n_iters=~p, n_trans=~p, n_drivers=~p, avg=~p, now=~p, prev=~p~n",
+%%	      [Iters, N, AliveN, BruttoAvg, Now, State#reporter_state.prev_micros]),
+    BruttoTps = ?AVOID_DIV_ZERO(?SECOND div BruttoAvg),
+    case Iters > 0 of
+	true ->
+	    io:format("TPC-B: ~p iter ~s~p diff ~p (~p) tps ~p avg micros ~p max micros ~p unfairness~n",
+		      [Iters, DiffSign, DiffTps, Tps, BruttoTps, Avg, Max, Unfairness]);
+	false ->
+	    io:format("TPC-B: ~p (~p) transactions per second, "
+		      "duration of longest transaction was ~p milliseconds~n",
+		      [Tps, BruttoTps, Max div 1000])
+    end,
+    State#reporter_state{prev_tps = Tps, prev_micros = Now}.
+
+signed_diff(Iters, Curr, Prev) ->
+    case Iters > 1 of
+	true  -> sign(Curr - Prev);
+	false -> sign(0)
+    end.
+    
+sign(N) when N > 0 -> {"+", N};
+sign(N) -> {"", N}.
+
+now_to_micros({Mega, Secs, Micros}) ->
+    DT = calendar:now_to_datetime({Mega, Secs, 0}),
+    S  = calendar:datetime_to_gregorian_seconds(DT),
+    (S * ?SECOND) + Micros.
+    
+start_drivers(RC, TC) ->
+    LastHistoryId = table_info(history, size),
+    Reuse = RC#run_config.reuse_history_id,
+    DS = #driver_state{tab_config       = TC,
+		       run_config       = RC,
+		       n_local_branches = 0,
+		       local_branches   = [],
+		       history_id       = LastHistoryId,
+		       reuse_history_id = Reuse},
+    Nodes = RC#run_config.driver_nodes,
+    NB = TC#tab_config.n_branches,
+    First = 0,
+    AllBranches = lists:seq(First, First + NB - 1),
+    ND = RC#run_config.n_drivers_per_node,
+    Spawn = fun(Spec) ->
+		    Node = Spec#driver_state.driver_node,
+		    spawn_link(Node, ?MODULE, driver_init, [Spec, AllBranches])
+	    end,
+    Specs = [DS#driver_state{driver_id = Id, driver_node = N}
+	     || N <- Nodes, 
+		Id <- lists:seq(1, ND)],
+    Specs2 = lists:sort(lists:flatten(Specs)),
+    {Specs3, OrphanBranches} = alloc_local_branches(AllBranches, Specs2, []),
+    case length(OrphanBranches) of
+	N when N =< 10 ->
+	    io:format("TPC-B: Orphan branches: ~p~n", [OrphanBranches]);
+	N ->
+	    io:format("TPC-B: Orphan branches: ~p~n", [N])
+    end,
+    [Spawn(Spec) || Spec <- Specs3].
+
+alloc_local_branches([BranchId | Tail], Specs, OrphanBranches) ->
+    Nodes = table_info({branch, BranchId}, where_to_write),
+    LocalSpecs = [DS || DS <- Specs,
+			lists:member(DS#driver_state.driver_node, Nodes)],
+    case lists:keysort(#driver_state.n_local_branches, LocalSpecs) of
+	[] ->
+	    alloc_local_branches(Tail, Specs, [BranchId | OrphanBranches]);
+	[DS | _] ->
+	    LocalNB = DS#driver_state.n_local_branches + 1,
+	    LocalBranches = [BranchId | DS#driver_state.local_branches],
+	    DS2 = DS#driver_state{n_local_branches = LocalNB,
+				  local_branches = LocalBranches},
+	    Specs2 = Specs -- [DS],
+	    Specs3 = [DS2 | Specs2],
+	    alloc_local_branches(Tail, Specs3, OrphanBranches)
+    end;
+alloc_local_branches([], Specs, OrphanBranches) ->
+    {Specs, OrphanBranches}.
+    
+driver_init(DS, AllBranches) ->
+    Seed = erlang:now(),
+    DS2 =
+	if
+	    DS#driver_state.n_local_branches =:= 0 ->
+		DS#driver_state{seed = Seed, 
+				n_local_branches = length(AllBranches),
+				local_branches   = AllBranches};
+	    true ->
+		DS#driver_state{seed = Seed}
+	end,
+    io:format("TPC-B: Driver ~p started as ~p on node ~p with ~p local branches~n",
+	      [DS2#driver_state.driver_id, self(), node(), DS2#driver_state.n_local_branches]),
+    driver_loop(DS2).
+
+driver_loop(DS) ->
+    receive
+	{From, report} ->
+	    From ! {self(), DS#driver_state.time},
+	    Acc = add_time(DS#driver_state.time, DS#driver_state.acc_time),
+	    DS2 = DS#driver_state{time=#time{}, acc_time = Acc}, % Reset timer
+	    DS3 = calc_trans(DS2),
+	    driver_loop(DS3);
+	{From, stop} ->
+	    Acc = add_time(DS#driver_state.time, DS#driver_state.acc_time),
+	    io:format("TPC-B: Driver ~p (~p) on node ~p stopped: ~w~n",
+		      [DS#driver_state.driver_id, self(), node(self()), Acc]),	
+	    From ! {self(), DS#driver_state.time},
+	    unlink(From),
+	    exit(stopped)
+    after 0 ->
+	    DS2 = calc_trans(DS),
+	    driver_loop(DS2)
+    end.
+
+calc_trans(DS) ->
+    {Micros, DS2} = time_trans(DS),
+    Time = DS2#driver_state.time,
+    Time2 = Time#time{n_trans = Time#time.n_trans + 1,
+		      acc_time = Time#time.acc_time + Micros,
+		      max_time = lists:max([Micros, Time#time.max_time])
+		     },
+    case DS#driver_state.reuse_history_id of
+	false ->
+	    HistoryId = DS#driver_state.history_id + 1,
+	    DS2#driver_state{time=Time2, history_id = HistoryId};
+	true ->
+	    DS2#driver_state{time=Time2}
+    end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%% Generate teller_id, account_id and delta
+%% Time the TPC-B transaction
+time_trans(DS) ->
+    OldSeed = get(random_seed), % Avoid interference with Mnesia
+    put(random_seed, DS#driver_state.seed),
+    Random    = random:uniform(),
+    NewSeed   = get(random_seed),
+    case OldSeed of
+	undefined -> erase(random_seed);
+	_         -> put(random_seed, OldSeed)
+    end,
+
+    TC = DS#driver_state.tab_config,
+    RC = DS#driver_state.run_config,
+    {Branchid, Args} = random_to_args(Random, DS),
+    {Fun, Mod} = trans_type(TC, RC),
+    {Time, Res} = timer:tc(?MODULE, real_trans, [RC, Branchid, Fun, Args, Mod]),
+
+    case Res of
+	AccountBal when is_integer(AccountBal) ->
+	    {Time, DS#driver_state{seed = NewSeed}};
+	Other ->
+	    exit({crash, Other, Args, Random, DS})
+    end.
+
+random_to_args(Random, DS) ->
+    DriverId = DS#driver_state.driver_id,
+    TC = DS#driver_state.tab_config,
+    HistoryId = DS#driver_state.history_id,
+    Delta = trunc(Random * 1999998) - 999999, % -999999 <= Delta <= +999999
+
+    Branches = DS#driver_state.local_branches,
+    NB = DS#driver_state.n_local_branches,
+    NT = TC#tab_config.n_tellers_per_branch,
+    NA = TC#tab_config.n_accounts_per_branch,
+    Tmp = trunc(Random * NB * NT),
+    BranchPos = (Tmp div NT) + 1,
+    BranchId =
+	case TC#tab_config.n_fragments of
+	    0 -> BranchPos - 1;
+	    _ -> lists:nth(BranchPos, Branches)
+	end,
+    RelativeTellerId = Tmp div NT,
+    TellerId = (BranchId * NT) + RelativeTellerId,
+    {AccountBranchId, AccountId} =
+	if
+	    Random >= 0.85, NB > 1 ->
+		%% Pick from a remote account
+                TmpAccountId= trunc(Random * (NB - 1) * NA),
+		TmpAccountBranchId = TmpAccountId div NA,
+		if
+		    TmpAccountBranchId =:= BranchId ->
+			{TmpAccountBranchId + 1, TmpAccountId + NA};
+		    true ->
+			{TmpAccountBranchId, TmpAccountId}
+		end;
+	    true ->
+		%% Pick from a local account
+		RelativeAccountId = trunc(Random * NA),
+		TmpAccountId = (BranchId * NA) + RelativeAccountId,
+		{BranchId, TmpAccountId}
+	end,
+    
+    {BranchId, [DriverId, BranchId, TellerId, AccountBranchId, AccountId, HistoryId, Delta]}.
+
+real_trans(RC, BranchId, Fun, Args, Mod) ->
+    Type = RC#run_config.activity_type,
+    case RC#run_config.spawn_near_branch of
+	false ->
+	    mnesia:activity(Type, Fun, Args, Mod);
+	true ->
+	    Node = table_info({branch, BranchId}, where_to_read),
+	    case rpc:call(Node, mnesia, activity, [Type, Fun, Args, Mod]) of
+		{badrpc, Reason} -> exit(Reason);
+		Other -> Other
+	    end
+    end.
+
+trans_type(TC, RC) ->
+    if
+	TC#tab_config.n_fragments =:= 0,
+	RC#run_config.use_sticky_locks =:= false ->
+	    {fun add_delta/7, mnesia};
+	TC#tab_config.n_fragments =:= 0,
+	RC#run_config.use_sticky_locks =:= true ->
+	    {fun sticky_add_delta/7, mnesia};
+	TC#tab_config.n_fragments > 0,
+	RC#run_config.use_sticky_locks =:= false ->
+	    {fun frag_add_delta/7, mnesia_frag}
+    end.
+
+%%
+%% Runs the TPC-B defined transaction and returns NewAccountBalance
+%%
+
+add_delta(DriverId, BranchId, TellerId, _AccountBranchId, AccountId, HistoryId, Delta) ->
+    %% Grab write lock already when the record is read 
+    
+    %% Add delta to branch balance
+    [B]  = mnesia:read(branch, BranchId, write),
+    NewB = B#branch{balance = B#branch.balance + Delta},
+    ok = mnesia:write(branch, NewB, write),
+
+    %% Add delta to teller balance
+    [T]  = mnesia:read(teller, TellerId, write),
+    NewT = T#teller{balance = T#teller.balance + Delta},
+    ok = mnesia:write(teller, NewT, write),
+
+    %% Add delta to account balance
+    [A]  = mnesia:read(account, AccountId, write),
+    NewA = A#account{balance = A#account.balance + Delta},
+    ok = mnesia:write(account, NewA, write),
+
+    %% Append to history log
+    History = #history{history_id   = {DriverId, HistoryId},
+		       account_id   = AccountId,
+		       teller_id    = TellerId,
+		       branch_id    = BranchId,
+		       amount       = Delta
+		      },
+    ok = mnesia:write(history, History, write),
+
+    %% Return account balance
+    NewA#account.balance.
+
+sticky_add_delta(DriverId, BranchId, TellerId, _AccountBranchId, AccountId, HistoryId, Delta) ->
+    %% Grab orinary read lock when the record is read
+    %% Grab sticky write lock when the record is written
+    %% This transaction would benefit of an early  stick_write lock at read
+
+    %% Add delta to branch balance
+    [B]  = mnesia:read(branch, BranchId, read),
+    NewB = B#branch{balance = B#branch.balance + Delta},
+    ok = mnesia:write(branch, NewB, sticky_write),
+
+    %% Add delta to teller balance
+    [T]  = mnesia:read(teller, TellerId, read),
+    NewT = T#teller{balance = T#teller.balance + Delta},
+    ok = mnesia:write(teller, NewT, sticky_write),
+
+    %% Add delta to account balance
+    [A]  = mnesia:read(account, AccountId, read),
+    NewA = A#account{balance = A#account.balance + Delta},
+    ok = mnesia:write(account, NewA, sticky_write),
+
+    %% Append to history log
+    History = #history{history_id   = {DriverId, HistoryId},
+		       account_id   = AccountId,
+		       teller_id    = TellerId,
+		       branch_id    = BranchId,
+		       amount       = Delta
+		      },
+    ok = mnesia:write(history, History, sticky_write),
+
+    %% Return account balance
+    NewA#account.balance.
+
+frag_add_delta(DriverId, BranchId, TellerId, AccountBranchId, AccountId, HistoryId, Delta) ->
+    %% Access fragmented table
+    %% Grab write lock already when the record is read 
+
+    %% Add delta to branch balance
+    [B] = mnesia:read(branch, BranchId, write),
+    NewB = B#branch{balance = B#branch.balance + Delta},
+    ok = mnesia:write(NewB),
+
+    %% Add delta to teller balance
+    [T] = mnesia:read({teller, BranchId}, TellerId, write),
+    NewT = T#teller{balance = T#teller.balance + Delta},
+    ok = mnesia:write(NewT),
+
+    %% Add delta to account balance
+    %%io:format("frag_add_delta(~p): ~p\n", [node(), {account, BranchId, AccountId}]),
+    [A] = mnesia:read({account, AccountBranchId}, AccountId, write),
+    NewA = A#account{balance = A#account.balance + Delta},
+    ok = mnesia:write(NewA),
+
+    %% Append to history log
+    History = #history{history_id   = {DriverId, HistoryId},
+		       account_id   = AccountId,
+		       teller_id    = TellerId,
+		       branch_id    = BranchId,
+		       amount       = Delta
+		      },
+    ok = mnesia:write(History),
+
+    %% Return account balance
+    NewA#account.balance.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Verify table consistency
+
+verify_tabs() ->
+    Nodes = mnesia:system_info(running_db_nodes),
+    case lists:member(node(), Nodes) of
+	true ->
+	    Tabs = [branch, teller, account, history],
+	    io:format("TPC-B: Verifying tables: ~w~n", [Tabs]),
+	    rpc:multicall(Nodes, mnesia, wait_for_tables, [Tabs, infinity]),
+	    
+	    Fun = fun() ->
+			  mnesia:write_lock_table(branch),
+			  mnesia:write_lock_table(teller),
+			  mnesia:write_lock_table(account),
+			  mnesia:write_lock_table(history),
+			  {Res, BadNodes} =
+			      rpc:multicall(Nodes, ?MODULE, count_balance, []),
+			  check_balance(Res, BadNodes)
+		  end,
+	    case mnesia:transaction(Fun) of
+		{atomic, Res} -> Res;
+		{aborted, Reason} -> {error, Reason}
+	    end;
+	false ->
+	    {error, "Must be initiated from a running db_node"}
+    end.
+
+%% Returns a list of {Table, Node, Balance} tuples
+%% Assumes that no updates are performed
+
+-record(summary, {table, node, balance, size}).
+
+count_balance() ->
+    [count_balance(branch, #branch.balance),
+     count_balance(teller, #teller.balance),
+     count_balance(account, #account.balance)].
+
+count_balance(Tab, BalPos) ->
+    Frags = table_info(Tab, frag_names),
+    count_balance(Tab, Frags, 0, 0, BalPos).
+
+count_balance(Tab, [Frag | Frags], Bal, Size, BalPos) ->
+    First = mnesia:dirty_first(Frag),
+    {Bal2, Size2} = count_frag_balance(Frag, First, Bal, Size, BalPos),
+    count_balance(Tab, Frags, Bal2, Size2, BalPos);
+count_balance(Tab, [], Bal, Size, _BalPos) ->
+    #summary{table = Tab, node = node(), balance = Bal, size = Size}.
+
+count_frag_balance(_Frag, '$end_of_table', Bal, Size, _BalPos) ->
+    {Bal, Size};
+count_frag_balance(Frag, Key, Bal, Size, BalPos) ->
+    [Record] = mnesia:dirty_read({Frag, Key}),
+    Bal2 = Bal + element(BalPos, Record),
+    Next = mnesia:dirty_next(Frag, Key),
+    count_frag_balance(Frag, Next, Bal2, Size + 1, BalPos).
+
+check_balance([], []) ->
+    mnesia:abort({"No balance"});
+check_balance(Summaries, []) ->
+    [One | Rest] = lists:flatten(Summaries),
+    Balance = One#summary.balance,
+    %% Size = One#summary.size,
+    case [S ||  S <- Rest, S#summary.balance =/= Balance] of
+	[] ->
+	    ok;
+	BadSummaries ->
+	    mnesia:abort({"Bad balance", One, BadSummaries})
+    end;
+check_balance(_, BadNodes) ->
+    mnesia:abort({"Bad nodes", BadNodes}).