Remove duplicates in the user_ips table and add an index

.travis.yml

@@ -12,6 +12,9 @@ cache:
     #
     - $HOME/.cache/pip/wheels
 
+addons:
+  postgresql: "9.4"
+
 # don't clone the whole repo history, one commit will do
 git:
   depth: 1

changelog.d/4370.misc

@@ -0,0 +1 @@
+Apply a unique index to the user_ips table, preventing duplicates.

synapse/storage/client_ips.py

@@ -65,7 +65,27 @@ def __init__(self, db_conn, hs):
             columns=["last_seen"],
         )
 
-        # (user_id, access_token, ip) -> (user_agent, device_id, last_seen)
+        self.register_background_update_handler(
+            "user_ips_remove_dupes",
+            self._remove_user_ip_dupes,
+        )
+
+        # Register a unique index
+        self.register_background_index_update(
+            "user_ips_device_unique_index",
+            index_name="user_ips_user_token_ip_unique_index",
+            table="user_ips",
+            columns=["user_id", "access_token", "ip"],
+            unique=True,
+        )
+
+        # Drop the old non-unique index
+        self.register_background_update_handler(
+            "user_ips_drop_nonunique_index",
+            self._remove_user_ip_nonunique,
+        )
+
+        # (user_id, access_token, ip,) -> (user_agent, device_id, last_seen)
         self._batch_row_update = {}
 
         self._client_ip_looper = self._clock.looping_call(
@@ -75,6 +95,106 @@ def __init__(self, db_conn, hs):
             "before", "shutdown", self._update_client_ips_batch
         )
 
+    @defer.inlineCallbacks
+    def _remove_user_ip_nonunique(self, progress, batch_size):
+        def f(conn):
+            txn = conn.cursor()
+            txn.execute(
+                "DROP INDEX IF EXISTS user_ips_user_ip"
+            )
+            txn.close()
+
+        yield self.runWithConnection(f)
+        yield self._end_background_update("user_ips_drop_nonunique_index")
+        defer.returnValue(1)
+
+    @defer.inlineCallbacks
+    def _remove_user_ip_dupes(self, progress, batch_size):
+
+        last_seen_progress = progress.get("last_seen", 0)
+
+        def get_last_seen(txn):
+            txn.execute(
+                """
+                SELECT last_seen FROM user_ips
+                WHERE last_seen > ?
+                ORDER BY last_seen
+                LIMIT 1
+                OFFSET ?
+                """,
+                (last_seen_progress, batch_size)
+            )
+            results = txn.fetchone()
+            return results
+
+        # Get a last seen that's sufficiently far away enough from the last one
+        last_seen = yield self.runInteraction(
+            "user_ips_dups_get_last_seen", get_last_seen
+        )
+
+        if not last_seen:
+            yield self._end_background_update("user_ips_remove_dupes")
+            defer.returnValue(0)
+
+        last_seen = last_seen[0]
+
+        def remove(txn, last_seen_progress, last_seen):
+            # This works by looking at all entries in the given time span, and
+            # then for each (user_id, access_token, ip) tuple in that range
+            # checking for any duplicates in the rest of the table (via a join).
+            # It then only returns entries which have duplicates, and the max
+            # last_seen across all duplicates, which can the be used to delete
+            # all other duplicates.
+            # It is efficient due to the existence of (user_id, access_token,
+            # ip) and (last_seen) indices.
+            txn.execute(
+                """
+                SELECT user_id, access_token, ip,
+                       MAX(device_id), MAX(user_agent), MAX(last_seen)
+                FROM (
+                    SELECT user_id, access_token, ip
+                    FROM user_ips
+                    WHERE ? <= last_seen AND last_seen < ?
+                    ORDER BY last_seen
+                ) c
+                INNER JOIN user_ips USING (user_id, access_token, ip)
+                GROUP BY user_id, access_token, ip;
+                HAVING count(*) > 1""",
+                (last_seen_progress, last_seen)
+            )
+            res = txn.fetchall()
+
+            # We've got some duplicates
+            for i in res:
+                user_id, access_token, ip, device_id, user_agent, last_seen = i
+
+                # Drop all the duplicates
+                txn.execute(
+                    """
+                    DELETE FROM user_ips
+                    WHERE user_id = ? AND access_token = ? AND ip = ?
+                    """,
+                    (user_id, access_token, ip)
+                )
+
+                # Add in one to be the last_seen
+                txn.execute(
+                    """
+                    INSERT INTO user_ips
+                    (user_id, access_token, ip, device_id, user_agent, last_seen)
+                    VALUES (?, ?, ?, ?, ?, ?)
+                    """,
+                    (user_id, access_token, ip, device_id, user_agent, last_seen)
+                )
+
+            self._background_update_progress_txn(txn, {"last_seen": last_seen})
+
+        yield self.runInteraction(
+            "user_ips_dups_remove", remove, last_seen_progress, last_seen
+        )
+
+        defer.returnValue(batch_size)
+
     @defer.inlineCallbacks
     def insert_client_ip(self, user_id, access_token, ip, user_agent, device_id,
                          now=None):
@@ -127,10 +247,10 @@ def _update_client_ips_batch_txn(self, txn, to_update):
                         "user_id": user_id,
                         "access_token": access_token,
                         "ip": ip,
-                        "user_agent": user_agent,
-                        "device_id": device_id,
                     },
                     values={
+                        "user_agent": user_agent,
+                        "device_id": device_id,
                         "last_seen": last_seen,
                     },
                     lock=False,
@@ -227,7 +347,7 @@ def get_user_ip_and_agents(self, user):
         results = {}
 
         for key in self._batch_row_update:
-            uid, access_token, ip = key
+            uid, access_token, ip, = key
             if uid == user_id:
                 user_agent, _, last_seen = self._batch_row_update[key]
                 results[(access_token, ip)] = (user_agent, last_seen)

synapse/storage/schema/delta/53/user_ips_index.sql

@@ -0,0 +1,26 @@
+/* Copyright 2018 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- delete duplicates
+INSERT INTO background_updates (update_name, progress_json) VALUES
+  ('user_ips_remove_dupes', '{}');
+
+-- add a new unique index to user_ips table
+INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+  ('user_ips_device_unique_index', '{}', 'user_ips_remove_dupes');
+
+-- drop the old original index
+INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+  ('user_ips_drop_nonunique_index', '{}', 'user_ips_device_unique_index');