Add 'state' as an index for the experiments table to take care of some

heavyweight queries in idlemail

sql/database-create.sql

@@ -782,7 +782,8 @@ CREATE TABLE experiments (
   instance_idx int(10) unsigned NOT NULL default '0',
   PRIMARY KEY  (eid,pid),
   KEY idx (idx),
-  KEY batchmode (batchmode)
+  KEY batchmode (batchmode),
+  KEY state (state)
 ) TYPE=MyISAM;
 
 --

sql/database-migrate.txt

@@ -3290,3 +3290,9 @@ last_net_act,last_cpu_act,last_ext_act);
 
       alter table node_types add column pxe_boot_path text \
           after modelnetedge_osid;
+
+4.50: Make 'state' an index in the experiment table to knock down a couple
+      of frequent heavyweight queries.
+
+      alter table experiments add index (state);
+