Database.SQL_SERVER should set more recent Hibernate dialect with Spring 4.3.x [SPR-15255]

[spring-projects-issues]

Stéphane Nicoll opened SPR-15255 and commented

See this spring boot issue

When the Database is set to SQL_SERVER, HibernateJpaVendorAdapter#determineDatabaseDialectClass sets the dialect to org.hibernate.dialect.SQLServerDialect. However there are multiple flavours of that dialect:

Microsoft SQL Server 2000	org.hibernate.dialect.SQLServerDialect
Microsoft SQL Server 2005	org.hibernate.dialect.SQLServer2005Dialect
Microsoft SQL Server 2008	org.hibernate.dialect.SQLServer2008Dialect

Ironically enough, if we don't see the dialect, Hibernate manages to detect the right one (in this particular case at least).

Should we consider stopping providing a dialect for SQL Server since we can't know which database is in use?

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Affects: 4.3.6

Issue Links:

• Default connection release mode inconsistent with Hibernate 5.1.1 [SPR-14548] #19116 Default connection release mode inconsistent with Hibernate 5.1.1
• Support for read-only transactions with Oracle 12c JDBC driver [SPR-15210] #19774 Support for read-only transactions with Oracle 12c JDBC driver
• Remove native support for Hibernate 3.6 and 4.x [SPR-13827] #18400 Remove native support for Hibernate 3.6 and 4.x

Referenced from: commits 7ed4884

[spring-projects-issues]

Juergen Hoeller commented

We generally intend to set the latest dialect for each particular database there, and we updated them for 5.0 already as part of #19116 / #18400. We can consider updating the dialect choices for 4.3.7 as well, depending on availability in the particular Hibernate version that we run against (since we're still supporting Hibernate 3.6+ there).

That said, since almost all databases have several dialects in place, the mechanism is arguably somewhat flawed in general. Could Boot simply not set the Database to begin with, leaving it entirely up to Hibernate?

[spring-projects-issues]

Juergen Hoeller commented

I see two candidates worth updating in 4.3.x: SQLServer2008Dialect and MySQL5Dialect, with their predecessors horribly outdated in the meantime, and with both available in Hibernate 3.6.10 already.

Since it's easy enough to do a custom override to older versions there, I see no need to be super-conversative here. Also, most classic Spring Framework applications probably set their own specific dialect anyway (i.e. don't use our JPA Database enum to begin with), in particular when talking to a specific outdated enterprise database...