Block Until Done Tool - How to get Input to run first?

[hike44]

Part of my flow requires that a join be done with an external file (it has previous week's values).  After that join is done, that file will be overwritten with new values (current week).

However I need to make sure that the Input runs first to bring in these values, before the output (overwrite) happens.  I tried using the Block Until Done tool, but it doesn't seem to be working.  The Output tool runs first and overwrites the file before Input tool runs.  

How do I correctly set this up?

[jrsheppard]

The block until done is only holding the records from processing from the top join until all records have finished processing from that join.  It doesn't mean that it will stop the flow of records from the bottom input.  Since Input / Output aren't directly connected, it won't work as intended.  You can try to use a throttle tool on the output - but that just slows down the processing of records.

The easiest way to fix the issue is to write to a different source.

[hike44 · Accepted solution]

I used a work around that solved for my specific use case but may not work for everyone else.

I added a Select tool after my final Join to specify the fields I needed and then did the Output.  This seems to have done the trick for my flow but I can definitely see other scenarios where this might not work and a true Block Until Done solution would be needed.