DISTINCT over Linked Server

Recently faced an issue where the destination table in a DB2 database had unique index and out insert from SQL Server using a linked server was failing. 

Even after using DISTINCT we received the same error:

OLE DB provider "MSDASQL" for linked server "SBLLS" returned message "[IBM][CLI Driver][DB2/XXXXX] SQL0803N  One or more values in the INSERT statement, UPDATE statement, or foreign key update caused by a DELETE statement are not valid because the primary key, unique constraint or unique index identified by "46" constrains table "MYDB.S_DESTINATION_UPDATE" from having duplicate values for the index key.  SQLSTATE=23505

Then realized that DISTINCT clause hass no effect when inserting data over a linked server. Immediately we switched our approach to insert DISTINCT data into a temporary table and then execute the insert into DB2 from SQL Server.

Learned something new....