MySQL query performance of Date sorted data I found some articles and questions on this issue but not sure if I got the answer. very new to db modeling so please bear with me 
My use case is:


Save user activities: I'm doing this by creating a one table and saving all user activities. The table has a ID, user_id(foreign key), time(Datetime), type(varchar), description 
Query the table for activities for a user for a time frame and potentially for a activity type.


My concern is the performance when the table has a large number of rows. My steps that I think will help improve is 


index the user_id
index the time


Then I can query for "user_is = 'abc' and time > somedate" or "user_is = 'abc' and time > somedate and type = xyz"

should I index type too? will having too many index have performance issues (when inserting new row or querying)?
What else can I do. Any advise will be greatly appreciated. 
Thanks in advance
Your query is presumably something like:

select a.*
from activities a
where user_is = 'abc' and time &gt; somedate


or

where user_is = 'abc' and time &gt; somedate and type = xyz


The best index for the first query is activities(user_is, time) and for the second activities(user_id, type, time).