In some cases its not that simple, for example with Hibernate if you select specific columns then the object you get back won't be put in its L1 cache because its not the full object.
So in some cases its better to select the whole object by primary key because some other method would do that later anyhow and now its in the cache and will skip an extra db call.
So in some cases its better to select the whole object by primary key because some other method would do that later anyhow and now its in the cache and will skip an extra db call.