fskorgen opened a new issue, #8223:
URL: https://github.com/apache/hop/issues/8223
### Apache Hop version?
2.19
### Java version?
21
### Operating system
Windows
### What happened?
**Affected:** 2.19.0 and earlier.
`Database.getQueryFieldsFromDatabaseMetaData` is the fallback used when a
database reports
`isSupportsPreparedStatementMetadataRetrieval() == false` — Oracle, H2,
Exasol4, Gupta, SybaseIQ.
The method cannot consume a standard `DatabaseMetaData.getColumns()` result:
- The **column name pattern is `""`**. Per the JDBC contract an empty
pattern matches nothing, so
the result set is empty whatever else is right. Verified on H2:
`getColumns("", "", "T", "")`
returns 0 rows, while `getColumns(null, null, "T", "%")` returns the 2
real columns.
- With no SQL passed in it also uses `databaseMeta.getName()` — the
**connection name** — as the
table-name pattern.
- It switches on `columns.getString("SOURCE_DATA_TYPE")` as though that
column held Hop type names
(`"Integer"`, `"BigDecimal"`, `"Internet Address"`). In JDBC,
`SOURCE_DATA_TYPE` is a `short`
holding the base type of a DISTINCT/REF column, and it is NULL for
ordinary columns. Verified on
H2: the value is null for both columns, and `switch` on a null String
throws
`NullPointerException`.
- It reads `SOURCE_MASK`, `SOURCE_DECIMAL_SYMBOL`, `SOURCE_GROUPING_SYMBOL`
and
`SOURCE_CURRENCY_SYMBOL`, none of which exist in
`DatabaseMetaData.getColumns()`. Verified on H2:
`Column "SOURCE_MASK" not found [42122-240]`.
- The returned `ResultSet` is not closed.
Any one of the metadata-contract errors is enough to stop the method. In
practice it only ever
"works" by throwing `Error in Database.getQueryFields()`, being caught, and
falling through to
`getQueryFieldsFallback` — which is why nobody has noticed.
### Steps to reproduce
Open a connection to an in-memory H2
(`isSupportsPreparedStatementMetadataRetrieval()` is false),
create `create table t (a int, b varchar(10))` and call
`getQueryFieldsFromDatabaseMetaData("select
* from t")`. The call fails rather than returning the two fields; each of
the metadata-contract
errors above can be observed on its own by calling
`DatabaseMetaData.getColumns` with the same
arguments the method uses.
### Suggested fix
Either restrict the method to the data-service connections whose result set
actually carries those
columns, or delete it and go straight to the fallback for these databases.
### Issue Priority
Priority: 3
### Issue Component
Component: Database
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