diff --git a/warcprox/stats.py b/warcprox/stats.py
index 9be1b54..660d4c7 100644
--- a/warcprox/stats.py
+++ b/warcprox/stats.py
@@ -120,7 +120,10 @@ class RethinkStatsDb:
         self.replicas = replicas or min(3, len(r.servers))
         self._ensure_db_table()
         self.options = options
-        self._executor = concurrent.futures.ThreadPoolExecutor(max_workers=10)
+
+        # only one worker thread to ensure consistency, see
+        # https://rethinkdb.com/docs/consistency/
+        self._executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
 
     def _ensure_db_table(self):
         dbs = self.r.db_list().run()
@@ -156,7 +159,7 @@ class RethinkStatsDb:
 
     def _tally(self, buckets, size, is_revisit):
         try:
-            self.logger.info("starting task self._tally(%s)", (buckets, size, is_revisit))
+            self.logger.debug("starting task self._tally(%s)", (buckets, size, is_revisit))
             for bucket in buckets:
                 bucket_stats = self.value(bucket) or _empty_bucket(bucket)
 
@@ -175,7 +178,7 @@ class RethinkStatsDb:
                 if sorted(result.values()) != [0,0,0,0,0,1] or [result["deleted"],result["skipped"],result["errors"]] != [0,0,0]:
                     raise Exception("unexpected result %s saving %s", result, record)
 
-            self.logger.info("finished task self._tally(%s)", (buckets, size, is_revisit))
+            self.logger.debug("finished task self._tally(%s)", (buckets, size, is_revisit))
         except:
             self.logger.error("unexpected problem tallying stats", exc_info=True)
 
@@ -198,6 +201,6 @@ class RethinkStatsDb:
 
     def notify(self, recorded_url, records):
         args = self._extract_stats_info(recorded_url, records)
-        self.logger.info("submitting task self._tally(%s)", args)
+        self.logger.debug("submitting task self._tally(%s)", args)
         self._executor.submit(self._tally, *args)