ORM performance cost

Question

Does anyone have any experience that indicates what kind of performance hit a developer could expect by choosing to use an ORM (in Django, RoR, SQLAlechemy, etc) over SQL an

Answer 1

Performance has always been an after thought in most DAL Layer development / architecture. I think its about time we start questioning the performance of these ORM tools, for the so-called ease of development they promise:

The 2 biggest areas of performance issues in ORMs are:

1. Inability to write Optimum SQL. You have to use an Object Query Language which is interpreted into SQL by the framework. Mostly it is good SQL, but often enough it is not the most efficient SQL.

2. Reflection. Most ORM frameworks use Reflection to populate objects with Data from the database. Reflection operations are costly, and with increasing number of load and data, the performance degradation becomes obvious.

Other performance issues that arise are because of inefficient Database Design or Entity Model design due to the tight coupling of Entity objects to Tables.