From: | David G Johnston <david(dot)g(dot)johnston(at)gmail(dot)com> |
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To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: "RETURNING PRIMARY KEY" syntax extension |
Date: | 2014-06-09 05:47:02 |
Message-ID: | 1402292822318-5806463.post@n5.nabble.com |
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Lists: | pgsql-hackers |
Ian Barwick wrote
> Hi,
>
> 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
> significant
> 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
> would
> be desirable to enable the JDBC driver to request only the primary key
> value(s).
Seems like a good idea.
> ERROR: Relation does not have any primary key(s)
"Relation does not have a primary key."
or
"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.
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