columns_on_demand

https://github.com/willbryant/columns_on_demand

Lazily loads large columns on demand. By default, does this for all TEXT (:text) and BLOB (:binary) columns, but a list of specific columns to load on demand can be given. This is useful to reduce the memory taken by Rails when loading a number of records that have large columns if those particular columns are actually not required most of the time. In this situation it can also greatly reduce the database query time because loading large BLOB/TEXT columns generally means seeking to other database pages since they are not stored wholly in the record's page itself. Although this plugin is mainly used for BLOB and TEXT columns, it will actually work on all types - and is just as useful for large string fields etc.