diff --git a/services/track-changes/app/coffee/HttpController.coffee b/services/track-changes/app/coffee/HttpController.coffee
index 0b59a6e1ec..9ede86f3ee 100644
--- a/services/track-changes/app/coffee/HttpController.coffee
+++ b/services/track-changes/app/coffee/HttpController.coffee
@@ -23,16 +23,20 @@ module.exports = HttpController =
 			res.send 204
 
 	flushAll: (req, res, next = (error) ->) ->
-		logger.log "flushing all projects"
-		UpdatesManager.flushAll (error, result) ->
+		# limit on projects to flush or -1 for all (default)
+		limit = if req.query.limit? then parseInt(req.query.limit, 10) else -1
+		logger.log {limit: limit}, "flushing all projects"
+		UpdatesManager.flushAll limit, (error, result) ->
 			return next(error) if error?
-			{failed, succeeded} = result
+			{failed, succeeded, all} = result
 			status = "#{succeeded.length} succeeded, #{failed.length} failed"
-			if failed.length > 0
+			if limit == 0
+				res.status(200).send "#{status}\nwould flush:\n#{all.join('\n')}\n"
+			else if failed.length > 0
 				logger.log {failed: failed, succeeded: succeeded}, "error flushing projects"
 				res.status(500).send "#{status}\nfailed to flush:\n#{failed.join('\n')}\n"
 			else
-				res.status(200).send "#{status}\nflushed all #{succeeded.length} projects\n"
+				res.status(200).send "#{status}\nflushed #{succeeded.length} projects of #{all.length}\n"
 
 	checkDanglingUpdates: (req, res, next = (error) ->) ->
 		logger.log "checking dangling updates"
diff --git a/services/track-changes/app/coffee/UpdatesManager.coffee b/services/track-changes/app/coffee/UpdatesManager.coffee
index ca79d26d59..f3571dc16d 100644
--- a/services/track-changes/app/coffee/UpdatesManager.coffee
+++ b/services/track-changes/app/coffee/UpdatesManager.coffee
@@ -145,12 +145,13 @@ module.exports = UpdatesManager =
 				async.parallelLimit jobs, 5, callback
 
 	# flush all outstanding changes
-	flushAll: (callback = (error, result) ->) ->
+	flushAll: (limit, callback = (error, result) ->) ->
 		RedisManager.getProjectIdsWithHistoryOps (error, project_ids) ->
 			return callback(error) if error?
 			logger.log {count: project_ids?.length, project_ids: project_ids}, "found projects"
 			jobs = []
-			for project_id in project_ids
+			selectedProjects = if limit < 0 then project_ids else project_ids[0...limit]
+			for project_id in selectedProjects
 				do (project_id) ->
 					jobs.push (cb) ->
 						UpdatesManager.processUncompressedUpdatesForProject project_id, (err) ->
@@ -159,8 +160,7 @@ module.exports = UpdatesManager =
 				return callback(error) if error?
 				failedProjects = (x.project_id for x in result when x.failed)
 				succeededProjects = (x.project_id for x in result when not x.failed)
-				RedisManager.getAllDocIdsWithHistoryOps (error, doc_ids) ->
-				callback(null, {failed: failedProjects, succeeded: succeededProjects})
+				callback(null, {failed: failedProjects, succeeded: succeededProjects, all: project_ids})
 
 	getDanglingUpdates: (callback = (error, doc_ids) ->) ->
 		RedisManager.getAllDocIdsWithHistoryOps (error, all_doc_ids) ->