Add Oracle import

[andredlng]

Summary

Adds datacontract import oracle, which creates a data contract from a live Oracle database:

datacontract import oracle --source localhost --service-name XEPDB1 --schema ADMIN --output datacontract.yaml

The guide previously told users to pull the DDL out of DBMS_METADATA.GET_DDL, import the file with import sql --dialect oracle, and then fill in a servers block of placeholder values.

The length rule is shared, not duplicated. Oracle reports a DATA_LENGTH for every column, but it is only part of the declared type for character and raw types — otherwise a DATE (length 7) would become DATE(7) and a CLOB (length 4000) CLOB(4000), neither of which matches what the test path reads back. That rule already existed inside native_type._map_reconstructed; it is now a named function both paths call.

--schema is upper-cased, since Oracle stores identifiers that way and a lower-case owner matches nothing.

Verified against a real Oracle

Import followed by datacontract test on the unedited file: 16/16 checks passed. The catalog for the seeded table shows why the length rule matters:

ORDER_ID    VARCHAR2      len 36    -> VARCHAR2(36)
ORDER_TOTAL NUMBER        len 22, precision 10, scale 2 -> NUMBER(10,2)
ORDERED_AT  TIMESTAMP(6)  len 11    -> TIMESTAMP(6)
NOTES       CLOB          len 4000  -> CLOB
CREATED_ON  DATE          len 7     -> DATE

A bug only the real run could find: Oracle returns catalog numbers as Decimal, and the first contract came out with

maxLength: !!python/object/apply:decimal.Decimal
- '36'

— a Python-specific YAML tag that no other tool can read and yaml.safe_load rejects. They are coerced to int, and a test asserts no !!python tag appears in the output.

Testing

tests/test_import_oracle.py — 10 tests. The seven that need a database are marked slow, matching test_test_oracle_xe.py, so they run in the dedicated CI job rather than on every invocation; the three argument-validation tests need no container. All ten pass locally against gvenzl/oracle-xe:21-slim-faststart, and the existing Oracle suite still passes.

Docs

New imports/oracle.md; testing/oracle.md gets the one-command step 3 with the DBMS_METADATA recipe reduced to a fallback, and step 2 renamed to "Authenticate" for consistency.

[github-actions]

📖 Docs preview

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Changed pages (most-changed first):

• imports/oracle.md — +27/−0
• testing/oracle.md — +10/−13
• imports/index.md — +5/−1
• commands/import.md — +1/−1
• imports/parquet.md — +1/−1
• imports/postgres.md — +1/−1
• imports/powerbi.md — +1/−1
• imports/protobuf.md — +1/−1
• imports/snowflake.md — +1/−1
• imports/spark.md — +1/−1
• imports/sql.md — +1/−1
• imports/sqlserver.md — +1/−1
• release-notes.md — +1/−0