feat: add Hive2Namespace implementation for Python

[jackye1995]

Summary

• Implements a Hive2 namespace adapter for lance-namespace Python client
• Adds integration with Apache Hive Metastore via Thrift protocol
• Enables Lance table management through Hive Metastore

Changes

Core Implementation

• python/lance_namespace/src/lance_namespace/hive.py: Complete Hive2Namespace implementation with:
  • HiveMetastoreClient helper class for Thrift connection management
  • Full namespace operations (list, create, drop, describe)
  • Complete table operations (register, create, drop, deregister, describe, list)
  • Schema conversion between PyArrow and Hive formats
  • Support for optional UGI authentication

Dependencies

• python/lance_namespace/pyproject.toml: Added optional hive2 extra with:
  • thrift>=0.13.0
  • hive-metastore-client>=1.0.9
  • Install with: pip install 'lance-namespace[hive2]'

Tests

• python/lance_namespace/tests/test_hive.py: Comprehensive test suite covering:
  • Initialization with and without dependencies
  • All namespace and table operations
  • Error handling and edge cases
  • Schema conversion utilities

Documentation

• docs/src/impls/hive.md: Added Python-specific documentation with usage examples
• python/lance_namespace/README.md: Updated with Hive2 backend instructions

Registration

• python/lance_namespace/src/lance_namespace/namespace.py: Registered hive2 implementation

Usage Example

from lance_namespace import connect

# Connect to Hive Metastore
namespace = connect("hive2", {
    "uri": "thrift://localhost:9083",
    "warehouse": "/user/hive/warehouse",
    "ugi": "user:group1,group2"  # Optional
})

# List databases
from lance_namespace import ListNamespacesRequest
response = namespace.list_namespaces(ListNamespacesRequest())

# Create a Lance table
import pyarrow as pa
import io

data = pa.table({"col1": [1, 2, 3], "col2": ["a", "b", "c"]})
buf = io.BytesIO()
with pa.ipc.new_stream(buf, data.schema) as writer:
    writer.write_table(data)

from lance_namespace import CreateTableRequest
request = CreateTableRequest(
    id=["database", "table_name"],
    mode="create"
)
response = namespace.create_table(request, buf.getvalue())

Test Plan

• Unit tests for all Hive2Namespace operations
• Mock-based testing for Hive client interactions
• Integration tests with actual Hive Metastore (requires HMS setup)

🤖 Generated with Claude Code

[jackye1995]

looks good to me