# datasets-conditional-loading Specification

## Purpose
Implement conditional loading for dataset-specific functionality to ensure dataset modules work without all optional dependencies while providing enhanced features when dependencies are available.

## ADDED Requirements

### Requirement: Dataset module conditional imports
Dataset modules SHALL conditionally import optional dependencies based on availability, allowing basic functionality without all dependencies.

#### Scenario: Dataset module imports with minimal dependencies
- **WHEN** importing fsspeckit.datasets with only base dependencies
- **AND** optional dependencies like duckdb are not installed
- **THEN** module imports successfully
- **AND** functions requiring missing dependencies raise clear errors when called

#### Scenario: Dataset modules detect available dependencies
- **WHEN** optional dependencies are installed
- **AND** dataset module is imported
- **THEN** enhanced functionality is available
- **AND** functions use available dependencies optimally

### MODIFIED Requirement: PyArrow dataset conditional loading
The pyarrow dataset module SHALL conditionally import polars and other dependencies while maintaining core PyArrow functionality.

#### Scenario: PyArrow dataset works without polars
- **WHEN** using fsspeckit.datasets.pyarrow
- **AND** polars is not installed
- **THEN** core PyArrow functionality works
- **AND** polars-specific features raise clear errors

#### Scenario: PyArrow dataset enhanced with polars
- **WHEN** polars is available
- **AND** using pyarrow dataset functions
- **THEN** polars integration features work
- **AND** performance optimizations are available

### MODIFIED Requirement: DuckDB dataset conditional loading
The DuckDB dataset module SHALL conditionally import duckdb and pyarrow dependencies.

#### Scenario: DuckDB dataset handles missing dependencies
- **WHEN** importing fsspeckit.datasets.duckdb
- **AND** duckdb is not installed
- **THEN** import succeeds without errors
- **AND** functions raise ImportError when called
- **AND** error message suggests installing fsspeckit[sql] or fsspeckit[datasets]

#### Scenario: DuckDB dataset with all dependencies
- **WHEN** duckdb and pyarrow are installed
- **AND** using duckdb dataset functions
- **THEN** full functionality is available
- **AND** performance optimizations work

### Requirement: Dataset function dependency validation
Dataset functions SHALL validate required dependencies before execution and provide helpful error messages.

#### Scenario: Function validates dependencies before processing
- **WHEN** calling a dataset function requiring specific dependencies
- **AND** those dependencies are missing
- **THEN** function raises ImportError immediately
- **AND** error message specifies required packages
- **AND** installation instructions are provided

#### Scenario: Function proceeds with available dependencies
- **WHEN** calling a dataset function with optional enhancements
- **AND** base dependencies are available
- **THEN** function executes with base functionality
- **AND** optional features are gracefully disabled

### Requirement: Dataset module feature detection
Dataset modules SHALL provide feature detection capabilities to query available functionality.

#### Scenario: Feature detection for available capabilities
- **WHEN** code queries dataset module capabilities
- **AND** some optional dependencies are missing
- **THEN** feature detection returns accurate availability
- **AND** code can adapt to available features

#### Scenario: Dynamic feature-based execution
- **WHEN** dataset code has multiple execution paths
- **AND** dependencies vary across environments
- **THEN** code selects optimal path based on available features
- **AND** falls back gracefully when features are missing

### MODIFIED Requirement: Dataset module imports structure
Dataset module __init__.py SHALL conditionally import submodules based on dependency availability.

#### Scenario: Dataset module imports work with minimal setup
- **WHEN** importing fsspeckit.datasets
- **AND** only base dependencies are installed
- **THEN** import succeeds
- **AND** available submodules are imported
- **AND** missing submodules are gracefully skipped

#### Scenario: Dataset module imports with full dependencies
- **WHEN** all optional dependencies are installed
- **AND** importing fsspeckit.datasets
- **THEN** all submodules are available
- **AND** full functionality is accessible