Suppose I have 7 fields referring from "emp" to other classes like
"department", "address", "boss" etc.
Using this approach I would have to perform 7 merges before the persist...
that is, 7 (potential) additional queries for one insert statement.
Isn't any other way to deal with this issue, except merge?
(ohh, and of course I can always write the "INSERT" statement myself, but
this misses the whole point of JPA...)
Wolfram Rittmeyer-2 wrote:
>
> gufiya wrote:
>> Thanks for the answers.
>> Indeed, merge() sounds better than explicit find() operation.
>> But still, doesn't it mean an additional access to the database?
>> One underlying query for merge() and another for persist()?
>
> Not necessarily. The EntityManager first looks if it already contains a
> managed object of the same type with the same identity. If so the state
> of your detached object is copied to the managed object and persisted at
> the end of the transaction (if no rollback occurs).
>
> --
> Wolfram Rittmeyer
>
>
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