[paomian]

• Updated documentation to clarify backend usage and import paths.
• Removed automatic backend selection; users must explicitly import the desired backend.
• Simplified error handling by consolidating GreptimeError into a single implementation.
• Enhanced type handling in the gRPC and PostgreSQL modules to ensure compatibility with shared schema.
• Removed legacy native module and associated imports.
• Added tests to verify that both backends correctly utilize the shared schema and handle errors appropriately.
• Ensured that the public schema is consistent across both backends.

[Copilot]

🟢 Approval recommended

No active review issues are reported for the refactor separating explicit backend selection from shared schema and error types.

No open issues 🎉

What changed in this PR

This PR separates backend selection from the SDK’s shared schema. Callers explicitly import the gRPC or PostgreSQL client, while both backends use the same public column types and GreptimeError.

Changes:

• Remove automatic backend selection and the legacy native import shim.
• Adapt PostgreSQL and Rust bindings to consume shared Python schema and error types.
• Update tests, examples, and documentation for explicit backend imports.

File	Description
tests/​test_types.py	Require public Column objects in PostgreSQL validation.
tests/​test_shared_schema.py	Add shared schema and error checks for both backends.
tests/​test_postgres.py	Update validation calls and strengthen import isolation checks.
tests/​test_postgres_schema_compat.py	Remove obsolete native-schema compatibility tests.
tests/​test_integration.py	Update imports and check bulk writer column types.
tests/​test_convert.py	Use explicit gRPC and native plugin imports.
tests/​test_backends.py	Verify root exports and backend import isolation.
README.zh-CN.md	Document explicit imports and refresh reference links.
README.md	Mirror backend import guidance and reference updates.
python/​greptimedb_ingester/​postgres.py	Use shared columns with explicit SQL type mappings.
python/​greptimedb_ingester/​grpc.py	Limit exports to backend-specific APIs.
python/​greptimedb_ingester/​_types.py	Clarify shared schema ownership and simplify error creation.
python/​greptimedb_ingester/​_native.py	Remove the legacy native import shim.
python/​greptimedb_ingester/​_errors.py	Define one backend-independent GreptimeError.
python/​greptimedb_ingester/​__init__.py	Remove automatic client selection and backend exports.
packages/​grpc/​src/​types.rs	Convert between shared Python columns and internal Rust types.
packages/​grpc/​src/​lib.rs	Stop registering native schema and error classes.
packages/​grpc/​src/​error.rs	Construct the shared Python error from Rust.
packages/​grpc/​src/​bulk.rs	Return public Python columns from the writer getter.
examples/​insert_example.py	Import Client explicitly from gRPC.
examples/​bulk_example.py	Import Client and WriteOptions from gRPC.
examples/​bench_write.py	Separate shared schema and gRPC imports.
docs/​usage.md	Update examples and backend selection guidance.
AGENTS.md	Document explicit imports and prohibit legacy shims.

_{Review effort: Balanced}