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 foreach row (id,hid,instance,etc...) in table1
   lookup row in table2 that contains id,hid
   lookup a row in table3 that contains id,hid,instance

 load all of table2 into a hash, keyed by "id,hid"
 load all of table3 into a hash, keyed by "id,hid,instance"
...
 foreach row (id,hid,instance,etc...) in table1
   do something with row data, $table2{"id,hid"} and $table3{"id,hid,i
+nstance"}