#3665 fix(targets): reuse SQLAlchemy inspector reflection cache Pull request opened by akashmalbari Closes #3478. Summary This updates

SQLConnector

to reuse a cached SQLAlchemy

Inspector

instance for repeated reflection calls instead of creating a new

sa.inspect(self._engine)

for each call. The affected methods now share the connector-level Inspector: •

table_exists()

•

schema_exists()

•

get_table_columns()

This preserves SQLAlchemy's

Inspector.info_cache

across reflection calls, allowing dialect-level reflection caching optimizations to work as intended. Cache invalidation Because the Inspector now persists across calls, this also adds a reflection cache clearing helper and clears the cache after connector-managed DDL operations such as: • creating schemas • creating tables • adding columns • renaming columns • altering column types This avoids stale reflection after the SDK itself changes the target schema. Tests Added regression coverage for: • reusing a single Inspector across repeated SQLConnector reflection calls • clearing the cached Inspector reflection cache • avoiding stale reflection state after connector-managed DDL Validation •

uv run pytest tests/sql/test_connector.py -q

•

uv run pytest tests/sql -q

•

uv sync --all-groups --all-extras --all-packages

•

uv run pytest tests -q

•

uvx nox -t typing

•

uvx pre-commit run --all-files

Summary by Sourcery Cache and reuse a SQLAlchemy Inspector within SQLConnector to enable reflection caching and invalidate it after connector-managed schema changes. Bug Fixes: • Ensure SQLConnector reuses a single SQLAlchemy Inspector instance for reflection so dialect-level reflection caches are preserved across calls. • Clear the Inspector reflection cache after connector-managed DDL operations (schema/table creation, column add/rename/type change, table recreation) to avoid stale metadata. Documentation: • Add AGENTS.md with contributor-facing guidance on development setup, commands, code style, exceptions, deprecation policy, architecture, testing, and project structure. Tests: • Add regression tests covering Inspector reuse across reflection methods, reflection cache clearing behavior, and cache invalidation after DDL operations. meltano/sdk