HHH-14985 H2Dialect does not work properly with h2 2.0.202 on inserts

[froque]

This should be cherry picked into Hibernate 5.x

[gavinking]

From which version of h2 is this change necessary?

[froque]

works with H2 1.3.176

[gavinking]

What i'm saying is that it should be written so that it checks the version number and adapts to the version of h2.

[vxel]

The change is necessary for all H2 2.0.x versions, i.e. starting at H2 2.0.202
See :
h2database/h2database#3231

[gavinking]

OK, great, then @froque would you please make the change to this PR to reflect that?

Do you understand what I'm asking?

[katzyn]

DEFAULT should be used for all versions of H2 unconditionally, it works with all versions. Even H2 1.0 (2006-12-17) supports it well.

Attempt to insert NULL into column with NOT NULL constraint is wrong by itself. H2 1.X accepted it for identity columns only, but H2 2.X follows the Standard here in default configuration and doesn't allow it any more.

[gavinking]

DEFAULT should be used for all versions of H2 unconditionally

Ah, OK, then that's different.

[katzyn]

Just for information: getIdentitySelectString() isn't compatible with H2 2.0 too and there is nothing to return for 2.0.202, 2.0.204 and later versions. 1.4.200 was the last version where current implementation can be used (with caution, because IDENTITY() isn't a reliable function, for example, it may return value from another table if trigger performed some operations.)

In Regular mode H2 2.0 provides only two normal ways to query what was actually inserted:

1. Standard data change delta tables: SELECT ID FROM FINAL TABLE (INSERT INTO TEST(C1, C2) VALUES (1, 2))
2. Statement.getGeneratedKeys(), if JDBC is used.

Few compatibility modes provide additional legacy functions for identity columns.

It looks like GetGeneratedKeysDelegate can be used for 2.0.202 and newer versions and perhaps it will be better to use it since H2 1.4.197, but it needs to be tested.

In 1.4.196 and older versions getGeneratedKeys() was implemented with SELECT SCOPE_IDENTITY() by itself, it means result set doesn't know real name of the column. But SCOPE_IDENTITY() at least doesn't return unexpected values from triggers.

[beikov]

Just for information: getIdentitySelectString() isn't compatible with H2 2.0

If java.sql.DatabaseMetaData#supportsGetGeneratedKeys returns true, which it does, it will use JDBC getGeneratedKeys, so this should be fine.

Changes look good. IMO we can merge this.

[gavinking]

@beikov but ... perhaps we should do this instead:

#4569

I'm not sure.

[beikov]

I think supportsInsertSelectIdentity should be conditional based on the dialect version as I think the final table syntax is only supported as of 1.4.200. Is that correct @katzyn ?

[gavinking]

I think supportsInsertSelectIdentity should be conditional based on the dialect version as I think the final table syntax is only supported as of 1.4.200. Is that correct @katzyn ?

Right, could be. But it's also unclear if it's actually better than using getGeneratedKeys() or whether they're the same, so I'm really not clear on anything here.

[gavinking]

Also, I mean, the Hibernate test suite doesn't run at all on H2 2. Many test failures. No idea if lots of things are broken or just one big thing.

[katzyn]

as I think the final table syntax is only supported as of 1.4.200

Data change delta tables are supported since H2 1.4.200, but they have some issues in this outdated version. They were resolved in H2 2.0.202.

Statement.getGeneratedKeys() returns values form the same stage as FINAL TABLE, but it is currently optimized a little bit better, because it collects values only from requested columns (data change delta tables collect complete rows).

[katzyn]

No idea if lots of things are broken or just one big thing.

Possibly many. INFORMATION_SCHEMA in H2 2.0 is compliant with the SQL Standard as it should in every DBMS, but it is very different from what H2 1.x has. Some non-standard additional tables were also modified to represent complete correct information.

It looks like Hibernate can't find indexes any more, it needs to use different queries for H2 2.0 and 1.*.

[beikov]

Thanks!