Index the value field of index nodes.

mayan/apps/document_indexing/migrations/0008_auto_20150729_1515.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('document_indexing', '0007_auto_20150729_0152'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='indexinstancenode',
+            name='value',
+            field=models.CharField(db_index=True, max_length=128, verbose_name='Value', blank=True),
+            preserve_default=True,
+        ),
+    ]

mayan/apps/document_indexing/models.py

@@ -125,7 +125,7 @@ class IndexInstanceNode(MPTTModel):
         verbose_name=_('Index template node')
     )
     value = models.CharField(
-        blank=True, max_length=128, verbose_name=_('Value')
+        blank=True, db_index=True, max_length=128, verbose_name=_('Value')
     )
     documents = models.ManyToManyField(
         Document, related_name='node_instances', verbose_name=_('Documents')