I have a very large possible data set that I am trying to visualize at once. The set itself consists of hundreds of thousands of segments, each of which is mapped to an id.

I have received a second data source that gives more real-time information for each segment, but the id's do not correspond to the id's I have. 

I have a 1:1 mapping of the data id's (9-character strings) to the current id's (long integers). The problem is that there are a lot of id's, and the data that is coming in is in no specific order.

The solution I came up with is to have a hash-map that maps the strings to the road id's. The problem is that I don't know if the hash-map will be efficient enough to have all 166k data entries.

Does anyone have any suggestions and/or hashing algorithms that I can use for this?