diff --git a/warcprox/dedup.py b/warcprox/dedup.py
index 289b252..d257c58 100644
--- a/warcprox/dedup.py
+++ b/warcprox/dedup.py
@@ -67,7 +67,6 @@ class LimitRevisitsMixin(object):
     """
     def __init__(self, options=warcprox.Options()):
         self.revisits = collections.defaultdict(set)
-        # TODO: define logger?
 
     def limit_revisits(self, recorded_url, hash=None, revisit_key=None):
         if not hash:
@@ -84,12 +83,65 @@ class LimitRevisitsMixin(object):
 
         hash_plus_url = b''.join((hash, recorded_url.url))
         if hash_plus_url in self.revisits[revisit_key]:
-            logging.info("skipping revisit for url %s and hash %s", recorded_url.url, hash)
+            logger.info("skipping revisit for url %s and hash %s", recorded_url.url, hash)
             return True
         else:
             self.revisits[revisit_key].add(hash_plus_url)
         return False
 
+class LimitRevisitsPGMixin(object):
+    """
+    Limit revisits recorded to one per revisit_key
+    """
+    def __init__(self, datasource, options=warcprox.Options()):
+        import psycopg2
+        from psycopg2 import extras # needed
+        self.datasource = datasource # "postgresql://user@db_host/db_name"
+        self.datatable  = datatable  # postgres table in db_name
+        # TODO here or elsewhere? verify partition table exists
+
+    def limit_revisits(self, recorded_url, hash=None, revisit_key=None):
+        if not hash:
+            hash = warcprox.digest_str(recorded_url.payload_digest, self.options.base32)
+        if not revisit_key:
+            # use ait-job-id if available
+            if (
+                recorded_url.warcprox_meta
+                and "metadata" in recorded_url.warcprox_meta
+                and "ait-job-id" in recorded_url.warcprox_meta["metadata"]
+            ):
+                revisit_key = recorded_url.warcprox_meta["metadata"]["ait-job-id"]
+            else:
+                revisit_key = 'all'
+        hash_plus_url = b''.join((hash, recorded_url.url))
+
+        query = f"SELECT exists(SELECT 1 FROM {revisit_key} WHERE hash_plus_url = {hash_plus_url} LIMIT 1;"
+
+        try:
+            conn = psycopg2.connect(self.datasource)
+        except Exception as e:
+            self.logger.warning("db connection failure: %s", e)
+            return False
+        cur = conn.cursor()
+        try:
+            cur.execute(query)
+        except Exception as e:
+            self.logger.warning("exception querying for %s in %s: %s", hash_plus_url, revisit_key, e)
+            return False
+        result = cur.fetchone()
+
+        if result[0]:
+            logging.info("skipping revisit for url %s and hash %s", recorded_url.url, hash)
+            return True
+        else:
+            query = "INSERT INTO {revisit_key} VALUES(revisit_key, hash_plus_url);"
+            try:
+                cur.execute(query)
+            except Exception as e:
+                self.logger.warning("exception inserting %s in %s: %s", hash_plus_url, revisit_key, e)
+
+        return False
+
 class DedupLoader(warcprox.BaseStandardPostfetchProcessor, DedupableMixin):
     def __init__(self, dedup_db, options=warcprox.Options()):
         warcprox.BaseStandardPostfetchProcessor.__init__(self, options=options)
@@ -427,11 +479,13 @@ class BatchTroughStorer(warcprox.BaseBatchPostfetchProcessor):
                 logging.warning(
                     'timed out saving dedup info to trough', exc_info=True)
 
-class BatchTroughLoader(warcprox.BaseBatchPostfetchProcessor, LimitRevisitsMixin):
+class BatchTroughLoader(warcprox.BaseBatchPostfetchProcessor, LimitRevisitsPGMixin):
     logger = logging.getLogger("warcprox.dedup.BatchTroughLoader")
 
     def __init__(self, trough_dedup_db, options=warcprox.Options()):
         warcprox.BaseBatchPostfetchProcessor.__init__(self, options)
+        LimitRevisitsPGMixin.__init__(self, datasource="", options)
+        # TODO: get datasource
         self.trough_dedup_db = trough_dedup_db
 
     def _startup(self):