在JPA中优化数百个选择查询

Question

I am using JPA and Facebook login for my app. After the user has logged in the server checks if each user is in our database by Facebook id. I created a for loop which execute a select query each time. This approach is slow. Is there some better way to make it faster?

The code is

for (User friend : friends) {
      User current = userManager.find(friend.facebookId);
If (null != current) { friend.setId(current.getId);}}

Answer 1

You could execute a single query with an IN instead. However with caching enabled, querying by id may be the fastest method if the friends are likely to be in the cache.

Select f from Friend f where f.id in :ids