Could any one please tell me why my system is waiting to get lock for an INSERT statement?
2014-05-21 07:52:49.965 PDT [9-1]LOG: process 31407 acquired ExclusiveLock on extension of relation 429298276 of database 21497 after 3219.963 ms
"on extension of relation" means that it needs to add 8KB to the end of the table. That it takes so long to obtain that locks suggests you have a some serious IO congestion.