From 3947da68ba51c6a2579ec90a997caf5fc7bfcc76 Mon Sep 17 00:00:00 2001
From: j <0x006A@0x2620.org>
Date: Wed, 6 Mar 2013 09:52:39 +0000
Subject: [PATCH] slice update to reduce memory usage

---
 pandora/sequence/migrations/0002_optimize1.py | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/pandora/sequence/migrations/0002_optimize1.py b/pandora/sequence/migrations/0002_optimize1.py
index e2d1a8571..9771fab73 100644
--- a/pandora/sequence/migrations/0002_optimize1.py
+++ b/pandora/sequence/migrations/0002_optimize1.py
@@ -29,12 +29,20 @@ class Migration(SchemaMigration):
 
         # Adding unique constraint on 'Sequence', fields ['sort', 'start', 'end', 'mode']
         db.create_unique('sequence_sequence', ['sort_id', 'start', 'end', 'mode'])
-
-
-        for s in orm['sequence.Sequence'].objects.all():
-            s.mode2 = s.mode == 'color' and 1 or 0
-            s.hash2 = int(s.hash, 16) - 9223372036854775808
-            s.save()
+        
+        def nslice(s, n):
+            while len(s) >= n:
+                yield s[:n]
+                s = s[n:]
+            if len(s):
+                yield s
+        
+        ids = [s['id'] for s in orm['sequence.Sequence'].objects.all().values('id')]
+        for i in nslice(ids, 10000):
+            for s in orm['sequence.Sequence'].objects.filter(id__in=i):
+                s.mode2 = s.mode == 'color' and 1 or 0
+                s.hash2 = int(s.hash, 16) - 9223372036854775808
+                s.save()
 
     def backwards(self, orm):
         # Removing unique constraint on 'Sequence', fields ['sort', 'start', 'end', 'mode']