zhengxiang378928908-code opened a new pull request, #11689:
URL: https://github.com/apache/seatunnel/pull/11689
### Purpose of this pull request
Fixes #11688.
`DmdbTypeConverter` has cases for `CHAR`, `CHARACTER`, `VARCHAR`, `VARCHAR2`
and `NVARCHAR`, but no case for `NCHAR`. Reading a Dameng table containing
`NCHAR` columns falls through to the `default` branch and fails:
```
ErrorCode:[COMMON-17], ErrorDescription:['Dameng' unsupported convert type
'nchar' of 'test' to SeaTunnel data type.]
```
In a multi-table job the catalog aggregates these into `COMMON-21` and the
whole job fails before any data is read.
`NCHAR` is the fixed-length national character type and the counterpart of
the already supported variable-length `NVARCHAR`. Supporting one but not the
other looks like an oversight rather than an intentional restriction.
**Length rule.** Every character type in this converter — `CHAR`,
`CHARACTER`, `VARCHAR`, `VARCHAR2` and `NVARCHAR` — uses `charTo4ByteLength`.
`NCHAR` follows the same rule, so the change introduces no new length behaviour
and needs no assumption about how Dameng reports lengths. That matters here
because Dameng's `LENGTH_IN_CHAR` parameter makes byte-vs-character length a
database-level setting, so I deliberately avoided reasoning that depends on it.
**Source type.** `NCHAR` gets its own case rather than joining the
`CHAR`/`CHARACTER` branch, because that branch rewrites `sourceType` to the
`CHAR` constant. Sharing it would report `NCHAR` columns as `CHAR(n)` and lose
the national character type name.
### Does this PR introduce _any_ user-facing change?
Yes, in the sense that a previously failing configuration now works: Dameng
tables containing `NCHAR` columns can now be read by the JDBC source, and those
columns map to SeaTunnel `STRING`.
No config option, default value, or existing type mapping changes. The added
case is purely additive, so this is backward compatible.
### How was this patch tested?
**Unit test.** Added `DmdbTypeConverterTest#testNchar`, mirroring the
existing `testNvarchar`, asserting the mapped data type, column length and
source type.
```
./mvnw test -pl seatunnel-connectors-v2/connector-jdbc
-Dtest=DmdbTypeConverterTest
Tests run: 35, Failures: 0, Errors: 0, Skipped: 0
```
Reverting only the `DmdbTypeConverter` change makes it fail with the
reported error, confirming it is a genuine regression test:
```
[ERROR] testNchar Time elapsed: 0.09 s <<< ERROR!
org.apache.seatunnel.common.exception.SeaTunnelRuntimeException:
ErrorCode:[COMMON-17],
ErrorDescription:['Dameng' unsupported convert type 'nchar' of 'test' to
SeaTunnel data type.]
```
**E2E test.** Added a `DM_NCHAR NCHAR(50)` column to `JdbcDmIT`, together
with the matching `fieldNames` entry, row value and the explicit insert column
list in `jdbc_dm_source_and_sink.conf`. The column is populated with multi-byte
content so the national character path is exercised end to end. `JdbcDmUpsetIT`
declares its own table and is unaffected.
I could not run this suite locally — Docker is unavailable in my environment
— so the `laglangyue/dmdb8` container path is validated by CI rather than by
me. `./mvnw test-compile` on `connector-jdbc-e2e-part-5` passes, and the
`CREATE_SQL` columns, `fieldNames`, row array, insert column list and
placeholder count are all consistent at 34 entries.
`./mvnw spotless:apply` was run over both modules.
### Note on overlap with #11684
#11684 adds `NVARCHAR2` support and also touches `JdbcDmIT` and
`jdbc_dm_source_and_sink.conf`. The converter changes sit in different branches
of the switch and do not overlap, but the two PRs both extend the same E2E
table, so whichever merges second will need a trivial rebase. I'm happy to
rebase this one whenever #11684 lands — or to combine them if a maintainer
would prefer a single PR covering the whole national character family.
### Check list
* [x] If any new Jar binary package adding in your PR, please add License
Notice according
[New License
Guide](https://github.com/apache/seatunnel/blob/dev/docs/en/developer/new-license.md)
— no new dependency
* [x] If necessary, please update the documentation to describe the new
feature. https://github.com/apache/seatunnel/tree/dev/docs — not applicable, no
option or documented behaviour changed
* [x] If necessary, please update `incompatible-changes.md` to describe the
incompatibility caused by this PR — not applicable, change is backward
compatible
* [x] If you are contributing the connector code, please check that the
following files are updated — not applicable, no new connector; E2E coverage
added to the existing `JdbcDmIT`
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