From 5971d240d458dbea23abed803aa3d7bf31c2efce Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 13 May 2015 15:26:49 +0100
Subject: [PATCH] Limit batch size

---
 synapse/storage/_base.py | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index f7b4def9e..f169884d8 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -28,6 +28,7 @@ from twisted.internet import defer
 
 from collections import namedtuple, OrderedDict
 import functools
+import itertools
 import simplejson as json
 import sys
 import time
@@ -875,11 +876,15 @@ class SQLBaseStore(object):
 
     def _get_events_txn(self, txn, event_ids, check_redacted=True,
                         get_prev_content=False):
-        return self._fetch_events_txn(
-            txn, event_ids,
-            check_redacted=check_redacted,
-            get_prev_content=get_prev_content,
-        )
+        N = 50  # Only fetch 100 events at a time.
+        return list(itertools.chain(*[
+            self._fetch_events_txn(
+                txn, event_ids[i*N:(i+1)*N],
+                check_redacted=check_redacted,
+                get_prev_content=get_prev_content,
+            )
+            for i in range(1 + len(event_ids) / N)
+        ]))
 
     def _invalidate_get_event_cache(self, event_id):
         for check_redacted in (False, True):