Allow the use of checkpoint to be optional

A new parameter use_checkpoints which defaults to be true can be either used in the replicator section of
ini files and/or used in the replication command or doc added to the replicator db. When this option is set
to false no checkpoints are taken. It should be used with caution and only for small dbs.

BugzID:14327

2 files changed, 14 insertions, 3 deletions

diff --git a/src/couch_replicator/src/couch_replicator.erl b/src/couch_replicator/src/couch_replicator.erl
index 1ce2cf545..b00efec70 100644
--- a/src/couch_replicator/src/couch_replicator.erl
+++ b/src/couch_replicator/src/couch_replicator.erl
@@ -68,7 +68,8 @@
     target_db_compaction_notifier = nil,
     source_monitor = nil,
     target_monitor = nil,
-    source_seq = nil
+    source_seq = nil,
+    use_checkpoints = true
 }).
 
 
@@ -455,6 +456,8 @@ handle_cast({report_seq, Seq},
     {noreply, State#rep_state{seqs_in_progress = NewSeqsInProgress}}.
 
 
+code_change(_OldVsn, OldState, _Extra) when tuple_size(OldState) =:= 30 ->
+    {ok, erlang:append_element(OldState, true)};
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
@@ -563,7 +566,8 @@ init_state(Rep) ->
             start_db_compaction_notifier(Target, self()),
         source_monitor = db_monitor(Source),
         target_monitor = db_monitor(Target),
-        source_seq = get_value(<<"update_seq">>, SourceInfo, ?LOWEST_SEQ)
+        source_seq = get_value(<<"update_seq">>, SourceInfo, ?LOWEST_SEQ),
+        use_checkpoints = get_value(use_checkpoints, Options, true)
     },
     State#rep_state{timer = start_timer(State)}.
 
@@ -672,6 +676,9 @@ changes_manager_loop_open(Parent, ChangesQueue, BatchSize, Ts) ->
 checkpoint_interval(_State) ->
     5000.
 
+do_checkpoint(#rep_state{use_checkpoints=false} = State) ->
+    NewState = State#rep_state{checkpoint_history = {[{<<"use_checkpoints">>, false}]} },
+    {ok, NewState};
 do_checkpoint(#rep_state{current_through_seq=Seq, committed_seq=Seq} = State) ->
     SourceCurSeq = source_cur_seq(State),
     NewState = State#rep_state{source_seq = SourceCurSeq},
diff --git a/src/couch_replicator/src/couch_replicator_utils.erl b/src/couch_replicator/src/couch_replicator_utils.erl
index d7778db87..1646c691d 100644
--- a/src/couch_replicator/src/couch_replicator_utils.erl
+++ b/src/couch_replicator/src/couch_replicator_utils.erl
@@ -228,6 +228,7 @@ make_options(Props) ->
     DefConns = couch_config:get("replicator", "http_connections", "20"),
     DefTimeout = couch_config:get("replicator", "connection_timeout", "30000"),
     DefRetries = couch_config:get("replicator", "retries_per_request", "10"),
+    UseCheckpoints = couch_config:get("replicator", "use_checkpoints", "true"),
     {ok, DefSocketOptions} = couch_util:parse_term(
         couch_config:get("replicator", "socket_options",
             "[{keepalive, true}, {nodelay, false}]")),
@@ -237,7 +238,8 @@ make_options(Props) ->
         {http_connections, list_to_integer(DefConns)},
         {socket_options, DefSocketOptions},
         {worker_batch_size, list_to_integer(DefBatchSize)},
-        {worker_processes, list_to_integer(DefWorkers)}
+        {worker_processes, list_to_integer(DefWorkers)},
+        {use_checkpoints, list_to_existing_atom(UseCheckpoints)}
     ])).
 
 
@@ -279,6 +281,8 @@ convert_options([{<<"socket_options">>, V} | R]) ->
     [{socket_options, SocketOptions} | convert_options(R)];
 convert_options([{<<"since_seq">>, V} | R]) ->
     [{since_seq, V} | convert_options(R)];
+convert_options([{<<"use_checkpoints">>, V} | R]) ->
+    [{use_checkpoints, V} | convert_options(R)];
 convert_options([_ | R]) -> % skip unknown option
     convert_options(R).