[hibernate-dev] Difference between Comment and Hint in Hibernate query

[Vlad Mihalcea]

I'm asking because the

org.hibernate.annotations.NamedNativeQuery or
org.hibernate.annotations.NamedQuery

define the comment attribute with the following Javadoc:

/**
 * A comment added to the generated SQL query.  Useful when engaging with DBA.
 */
String comment() default "";

So, Hibernate clients could use the comment attribute in order to supply an
Oracle query hint, right?

In this case, should we treat this attribute as a query hint so that the
Oracle/SQL Server hint logic applies to this one as well?

Vlad

On Tue, Aug 1, 2017 at 4:07 PM, Steve Ebersole <steve at hibernate.org> wrote:

> Query hints are hints for the database' s query parser/optimizer.
>
> A comment is a... well a comment :)
>
> On Tue, Aug 1, 2017, 6:37 AM Vlad Mihalcea <mihalcea.vlad at gmail.com>
> wrote:
>
>> Hi,
>>
>> While working on integrating a Pull Request, I realized that the
>> org.hibernate.engine.spi.QueryParameters provides these two attributes:
>>
>> private String comment;
>> private List<String> queryHints;
>>
>> Both these two are to be sent to the database, so why do we have both?
>>
>> I also noticed that only for Query Hints we do take into consideration DB
>> specific query hint syntax:
>>
>> // Keep this here, rather than moving to Select.  Some Dialects may
>> need the hint to be appended to the very
>> // end or beginning of the finalized SQL statement, so wait until
>> everything is processed.
>> if ( parameters.getQueryHints() != null &&
>> parameters.getQueryHints().size() > 0 ) {
>>    sql = dialect.getQueryHintString( sql, parameters.getQueryHints() );
>> }
>>
>> Shouldn't we only have either comment or queryHints? Or what is the
>> difference between these two?
>>
>> Vlad
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>