[hibernate-dev] Various "row value construct" alike syntax and Dialect class

Steve Ebersole steve at hibernate.org
Tue May 29 10:48:24 EDT 2012

On Sun 27 May 2012 02:52:23 AM CDT, Łukasz Antoniak wrote:
> The initial question here is how to distinguish dialects that support
> statements like:
> update ParentEntity_AUD set REVEND=? where (id, REV) IN (select id,
> REV from HT_ChildEntity_AUD)

Ok.  And this form comes about because of the multi-table HQL splitting 
to use temp tables right?

As an alternative suggestion, why don't we just have envers directly 
perform an SQL UPDATE?  Its really just the ParentEntity_AUD table you 
want to update right?  And this is really just to lock the table right?

> > I am not understanding the need for
> > supportsRowValueConstructorSyntaxInSelectList. What exactly is the
> > purpose of grouping the values together in a select list? And in fact
> > you are not even using tuple (row value constructor) syntax in any of
> > the selects.
> I can see that people name this type of SQL queries ("where (a1, b1)
> IN (select c1, d1 from another_table)") as row value constructor, for
> example here:
> http://connect.microsoft.com/SQLServer/feedback/details/299231/add-support-for-ansi-standard-row-value-constructors.
> Maybe the name "supportsRowValueConstructorSyntaxInSubquery" would be
> more accurate.

Ok, then the issue is naming.  See the issue is not the subquery.  The 
subquery does not even have a row value constructor; "select c1, d1" is 
just a simple select list.  The problem is that the dialect does not 
support the use of a subquery as the predicate of a logical expression 
where the other predicate is a tuple.  Basically they are doing too 
simplistic of type checking on the 2 predicates.  So maybe 

I assume it is the same problem with all forms of logical expressions 
(=, !=, >, etc), not just IN?  Could you verify that?

We might want to consider consolidating these together as well into a 
composite class that reports the dialects level of tuple support.  That 
unfortunately would have to wait for the next major rev.

> > Why would the third query fall into
> > supportsRowValueConstructorSyntaxInInList?
> Taken into consideration the grow of Dialect class and based on the
> table posted here:
> http://lists.jboss.org/pipermail/hibernate-dev/2012-May/008511.html.

My point is just that the third query does not involve an IN 
expression.  So why would it fall under 

steve at hibernate.org

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