temp DB advice - Using Temporary tables

I am working a report, where in the result is combination of multiple #temp tables. Structure is as below

1. Stored procedure 1 which has a temp table which gives a 0.5 million rows

2. Stored procedure 2 which has a temp table which give 0.1 million rows

Finally i need to combine the result set of above 2 SP , again use a temp table and make one final result set for report. Now i am worried about the performance, later if data increases, will it effect temp db. We usually stage the data monthly , in a month it Database may contain about 1 million rows. How much is the maximum capacity temp db accommodates. Will it effect with above approach.

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Link to original article：https://stackoverflow.com/questions/30771549/temp-db-advice-using-temporary-tables