Add index(idx) to experiment_stats table.

sql/database-create.sql

@@ -203,6 +203,7 @@ CREATE TABLE experiment_stats (
   maxlinks tinyint(3) unsigned default '0',
   batch tinyint(3) unsigned default '0',
   PRIMARY KEY  (eid,pid,idx)
+  KEY idx (idx)
 ) TYPE=MyISAM;
 
 --

sql/database-migrate.txt

@@ -401,3 +401,9 @@ last_net_act,last_cpu_act,last_ext_act);
 	  PRIMARY KEY  (node_id,veth_id),
 	  KEY IP (IP)
 	) TYPE=MyISAM;
+
+1.140: Add index to experiment_stats table to speed up big joins by
+       several orders of magnitude!
+
+       alter table experiment_stats add index(idx);
+