rzo1 commented on code in PR #144:
URL: https://github.com/apache/openjpa/pull/144#discussion_r3588337324
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openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/jpql/functions/TestEJBQLFunction.java:
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Review Comment:
Thanks for the report — I could reproduce this and tracked it down.
I debugged it with a small standalone `main()` against a fresh in-memory
HSQLDB (`jdbc:hsqldb:mem:x`), just dumping `DatabaseMetaData.getTables` /
`getColumns` output. On a completely empty database:
```
getTables(null, null, "TRANSLATIONS", null)
-> CAT=PUBLIC SCHEM=INFORMATION_SCHEMA NAME=TRANSLATIONS TYPE=SYSTEM TABLE
getColumns(null, null, "TRANSLATIONS", null)
-> 12 rows, all TABLE_SCHEM=INFORMATION_SCHEMA
getColumns(null, "PUBLIC", "TRANSLATIONS", null)
-> (no rows)
```
So the SQL standard defines an information-schema view named `TRANSLATIONS`,
and HSQLDB implements it. Since the test entity maps to
`@Table(name="TRANSLATIONS")` without a schema, OpenJPA's schema reflection
calls `getColumns` with a null schema pattern, gets back the columns of
`INFORMATION_SCHEMA.TRANSLATIONS`, and concludes the table already exists but
is missing the entity columns — hence the `ALTER TABLE TRANSLATIONS ADD COLUMN
id BIGINT` against `PUBLIC`, where no such table exists.
The generic code already has a filter for exactly this
(`DBDictionary.isSystemTable` / `systemSchemaSet`, consulted in
`SchemaGenerator.generateTables`), and the Oracle/Postgres dictionaries use it
— the HSQL dictionary just never registers its system schemas. Maybe something
like this works (in the `HSQLDictionary` constructor):
```java
// HSQLDB reports the tables and views of its system schemas (e.g.
// INFORMATION_SCHEMA.TRANSLATIONS) via DatabaseMetaData when no
// schema is specified; filter them out so they are not mistaken
// for user tables during schema reflection (OPENJPA-2940).
systemSchemaSet.addAll(Arrays.asList(
"INFORMATION_SCHEMA", "SYSTEM_LOBS"
));
```
With that change, `TestTablePerClassInheritanceWithAbstractRoot` (the test
owning the `TRANSLATIONS` entity) passes on `-Ptest-hsqldb`, and the
sequence/generator tests still pass. I also checked the rest of the test suite
for other collisions with HSQLDB's information-schema names — `TRANSLATIONS` is
the only one.
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