On 09/06/14 17:47, David G Johnston wrote:
Ian Barwick wrote

The JDBC API provides the getGeneratedKeys() method as a way of retrieving
primary key values without the need to explicitly specify the primary key
column(s). This is a widely-used feature, however the implementation has
performance drawbacks.

Currently this feature is implemented in the JDBC driver by appending
"RETURNING *" to the supplied statement. However this means all columns of
affected rows will be returned to the client, which causes significant
performance problems, particularly on wide tables. To mitigate this, it
be desirable to enable the JDBC driver to request only the primary key
Seems like a good idea.

      ERROR:  Relation does not have any primary key(s)
"Relation does not have a primary key."
"Relation has no primary key." (preferred)

By definition it cannot have more than one so it must have none.

It could have multiple unique constraints but I do not believe they are
considered if not tagged as primary.

David J.

View this message in context: 
Sent from the PostgreSQL - hackers mailing list archive at Nabble.com.

From memory all unique keys can be considered 'candidate primary keys', but only one can be designated 'the PRIMARY KEY'.

I also like your preferred error message, and to the full extent of my decidedly Non-Authority, I hereby authorise it! :-)


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