What I'm trying to do is traverse a known path in a given direction for a given distance.

What I have done so far is build a temp table of the path in the order I want to travel and it looks like:
| edge_id | source | target | cost | geom |
|---------|---------|---------|------|------- |
|   208346 | 167398 | 50564  |  148.55814507696616 | "" |
|   118186 | 167397 | 167398 |  18.917451445786348 | "" |
|   118185 | 167397 | 97888  |  5.577629837679091 | "" |
|   58802  | 97888  | 97889  |  87.04193787193802 | "" |
|   118187 | 97889  | 167399 |  95.53741276977404 | "" |

now I believe I should add a ```dir``` and ```reverse_cost``` columns and set value to something.

I'm assuming I can set the values of ```dir``` and ```reverse_cost``` based on the ```source``` and ```target``` columns, do I also need to change the value of ```cost``` maybe invert?

I can not figure out how to wright an update query to add the correct info into the table to then be able to run ```pgr_withPointsDD```