Optimizing EF to populate a table using a DTO?

Question

Upon attempting to populate a grid on the UI layer, the UI asks the BI layer for a list of results, EF returns the list of each result, and they are cast into a DTO that pulls in some additional information, this is converted to a list and returned to the UI layer.

The performance is impossibly slow. EF is creating a new context and hitting the DB for each individual result. This is because the DTO class will create a new dbcontext each time it is initialized if it is no longer open/active. Finalization of the class closes out the context. I believe this is what is killing performance.

Is there any way to batch something like this? In SQL i would performance a JOIN on the tables i need to get the resulting data loaded into a dataset. In EF when i create the DTO i then access the mapped objects relations and access data from other objects as such.

How should I access a large amount of records via EF to be returned to a UI layer grid when i need to access some information that is not stored in that particular entity object? (an example of this would be having a relation between users -> customers via the customer_userID -> userID PK. And wanting to display the User's Name, once i have the Customer object i need to then query the User object for the Users name in relation to that ID.

Anyone have any articles that can point me the correct way?

Answer 1

Functions that were passing a large amount of data to the UI layer were causing the issues. Often because the object from the DB layer had to have some operations performed on it before it could be passed to the UI layer. In essence some of the list generating functions were causing the store to create a new context for each individual request.

Just-in-time paging was one performance boost, so as to request a starting offset and a record count. What is important to note there is we had to create functions to simply return the total counts so the UI grids knew how many records they were dealing with.

The next fix was on the functions that apply BI rules to the objects before they are passed to the UI layer. In these cases we open a new context and pass that into the function, so it uses that context and only closes it out after the results are all completed.