SSIS Data Lookup Question

Hi, I'm transferring lots of rows (each row is a problem) from an oltp database to a datawarehouse. These problems (rows) are transferred to the fact table. And a problem has attributes like status and logdate and solved_date (default null) and a sequence number. I also check every day for new problems in the source. Now the thing is ... I can write an SQL query to incrementally add new rows by using the sequence number as parameter. This is to lower querying time (BECAUSe the problem table has about 2.000.000 rows)

The Actual Question: I also need to write a query to update the tables in the Datawarehouse. For example when a status of a problem changes. When status changes from "unsolved" to "solved" it gets a date in the solved_date attribute. Now ... How can I write a query that goes fast through those 2000000 rows? Now I can't use the sequence_number because its not known when the problem gets solved. There is the fact that I run a query every day, so maybe I need to look at problems where a solved date is added on that day? Im just a novice in sql so maybe you guys know ways to do fast lookups in many rows? Or are there Data Flow tasks I can use? I was thinking about the slowly changing dimension but thats for dimensions right? :) So maybe any other tasks that are possible? I just need to put back on track because I cant find a good way to do this.