Error: Database errors occurred: server closed the connection unexpectedly

we are getting error mentioned below while loading data from oracle to vertica using informatica 9.5 in Unix server .After loading 2.5 million records (instead of 6 million records) getting error. But same we ran in informatica 8.6(Windows server), it loaded 6 millon records. Error: WRT_8229 : Database errors occurred: FnName: Execute -- server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request. FnName: Execute -- 523 158