diff --git a/tests/test_warcprox.py b/tests/test_warcprox.py
index 5587d8f..e8c140b 100755
--- a/tests/test_warcprox.py
+++ b/tests/test_warcprox.py
@@ -1721,6 +1721,24 @@ def test_payload_digest(warcprox_, http_daemon):
     req, prox_rec_res = mitm.do_GET()
     assert warcprox.digest_str(prox_rec_res.payload_digest) == GZIP_GZIP_SHA1
 
+def test_trough_segment_promotion(warcprox_):
+    if not warcprox_.options.rethinkdb_trough_db_url:
+        return
+    cli = warcprox.trough.TroughClient(
+            warcprox_.options.rethinkdb_trough_db_url, 3)
+    promoted = []
+    def mock(segment_id):
+        promoted.append(segment_id)
+    cli.promote = mock
+    cli.register_schema('default', 'create table foo (bar varchar(100))')
+    cli.write('my_seg', 'insert into foo (bar) values ("boof")')
+    assert promoted == []
+    time.sleep(3)
+    assert promoted == ['my_seg']
+    promoted = []
+    time.sleep(3)
+    assert promoted == []
+
 if __name__ == '__main__':
     pytest.main()
 
diff --git a/warcprox/dedup.py b/warcprox/dedup.py
index 2364d41..d1e456d 100644
--- a/warcprox/dedup.py
+++ b/warcprox/dedup.py
@@ -262,7 +262,7 @@ class TroughDedupDb(object):
     def __init__(self, options=warcprox.Options()):
         self.options = options
         self._trough_cli = warcprox.trough.TroughClient(
-                options.rethinkdb_trough_db_url)
+                options.rethinkdb_trough_db_url, promotion_interval=60*60)
 
     def start(self):
         self._trough_cli.register_schema(self.SCHEMA_ID, self.SCHEMA_SQL)
diff --git a/warcprox/trough.py b/warcprox/trough.py
index ec3a032..6cbe1dd 100644
--- a/warcprox/trough.py
+++ b/warcprox/trough.py
@@ -1,7 +1,7 @@
 '''
 warcprox/trough.py - trough client code
 
-Copyright (C) 2013-2017 Internet Archive
+Copyright (C) 2017 Internet Archive
 
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
@@ -28,17 +28,69 @@ import requests
 import doublethink
 import rethinkdb as r
 import datetime
+import threading
+import time
 
 class TroughClient(object):
     logger = logging.getLogger("warcprox.trough.TroughClient")
 
-    def __init__(self, rethinkdb_trough_db_url):
+    def __init__(self, rethinkdb_trough_db_url, promotion_interval=None):
+        '''
+        TroughClient constructor
+
+        Args:
+            rethinkdb_trough_db_url: url with schema rethinkdb:// pointing to
+                trough configuration database
+            promotion_interval: if specified, `TroughClient` will spawn a
+                thread that "promotes" (pushed to hdfs) "dirty" trough segments
+                (segments that have received writes) periodically, sleeping for
+                `promotion_interval` seconds between cycles (default None)
+        '''
         parsed = doublethink.parse_rethinkdb_url(rethinkdb_trough_db_url)
         self.rr = doublethink.Rethinker(
                 servers=parsed.hosts, db=parsed.database)
         self.svcreg = doublethink.ServiceRegistry(self.rr)
         self._write_url_cache = {}
         self._read_url_cache = {}
+        self._dirty_segments = set()
+        self._dirty_segments_lock = threading.RLock()
+
+        self.promotion_interval = promotion_interval
+        self._promoter_thread = None
+        if promotion_interval:
+            self._promoter_thread = threading.Thread(
+                    target=self._promotrix, name='TroughClient-promoter',
+                    daemon=True)
+            self._promoter_thread.start()
+
+    def _promotrix(self):
+        while True:
+            time.sleep(self.promotion_interval)
+            try:
+                with self._dirty_segments_lock:
+                    dirty_segments = list(self._dirty_segments)
+                    self._dirty_segments.clear()
+                logging.info('promoting %s trough segments')
+                for segment in dirty_segments:
+                    try:
+                        self.promote(segment)
+                    except:
+                        logging.error(
+                                'problem promoting segment %s', exc_info=True)
+            except:
+                logging.error(
+                        'caught exception doing segment promotion',
+                        exc_info=True)
+
+    def promote(self, segment_id):
+        url = os.path.join(self.segment_manager_url(), 'promote')
+        payload_dict = {'segment': segment_id}
+        response = requests.post(url, json=payload_dict)
+        if response.status_code != 200:
+            raise Exception(
+                    'Received %s: %r in response to POST %s with data %s' % (
+                        response.status_code, response.text, url,
+                        json.dumps(payload_dict)))
 
     @staticmethod
     def sql_value(x):
@@ -116,12 +168,15 @@ class TroughClient(object):
                     self._read_url_cache[segment_id])
         return self._read_url_cache[segment_id]
 
-    def write(self, segment_id, sql_tmpl, values, schema_id='default'):
+    def write(self, segment_id, sql_tmpl, values=(), schema_id='default'):
         write_url = self.write_url(segment_id, schema_id)
         sql = sql_tmpl % tuple(self.sql_value(v) for v in values)
 
         try:
             response = requests.post(write_url, sql)
+            if segment_id not in self._dirty_segments:
+                with self._dirty_segments_lock:
+                    self._dirty_segments.add(segment_id)
         except:
             del self._write_url_cache[segment_id]
             self.logger.error(
@@ -137,7 +192,7 @@ class TroughClient(object):
             return
         self.logger.debug('posted %r to %s', sql, write_url)
 
-    def read(self, segment_id, sql_tmpl, values):
+    def read(self, segment_id, sql_tmpl, values=()):
         read_url = self.read_url(segment_id)
         if not read_url:
             return None
@@ -173,7 +228,8 @@ class TroughClient(object):
             response.raise_for_status()
 
     def register_schema(self, schema_id, sql):
-        url = '%s/schema/%s/sql' % (self.segment_manager_url(), schema_id)
+        url = os.path.join(
+                self.segment_manager_url(), 'schema', schema_id, 'sql')
         response = requests.put(url, sql)
         if response.status_code not in (201, 204):
             raise Exception(