Cache & State Interview Questions

Cache normalization flattens nested data using unique identifiers. Implements automatic ID generation, reference handling. Features: customizable key fields, type policies. Essential for consistent data representation and updates.

Type policies define how types are stored and retrieved from cache. Configure key fields, field behaviors. Features: custom merge functions, field read/write functions. Controls cache behavior per GraphQL type.

Local state through reactive variables, local-only fields. Implement client-side resolvers, type extensions. Features: @client directive, local mutations. Manages UI state alongside server data.

Field policies customize individual field behavior. Define read/write functions, merge strategies. Features: computed fields, custom caching logic. Handles complex field requirements.

Cache updates through update functions, refetchQueries. Implement optimistic updates, cache modifications. Features: automatic updates, manual cache writes. Ensures cache consistency after mutations.

Cache persistence stores cache data locally. Uses apollo3-cache-persist. Features: automatic persistence, custom storage. Enables offline support, faster initial loads.

Cache eviction through evict method, garbage collection. Implement cache cleanup, reference management. Features: automatic garbage collection, manual eviction. Manages cache size and memory usage.

Cache redirects customize cache data access. Define field reading behavior, data relationships. Features: custom resolvers, field policies. Handles complex data relationships and queries.

Optimistic responses update UI before server response. Implement temporary cache updates, rollback handling. Features: immediate feedback, error recovery. Improves perceived performance.

Cache initialization sets up initial cache state. Configure type policies, initial data. Features: preloaded state, type configuration. Essential for proper cache setup and behavior.

Pagination through field policies, merge functions. Implement cursor-based/offset pagination. Features: automatic merging, custom merge strategies. Manages paginated data in cache.

Reactive variables manage local state. Independent of GraphQL operations. Features: direct reads/writes, automatic updates. Simplifies local state management.

Cache invalidation through evict, modify methods. Implement selective updates, refetching. Features: field-level invalidation, type-level eviction. Ensures data freshness.

Cache policies control data reading/writing. Types: cache-first, network-only, etc. Features: customizable per query, default settings. Balances performance and data freshness.

Cache conflicts through merge functions, conflict resolution. Implement custom merging logic, update priorities. Features: deterministic merging, conflict detection. Maintains cache consistency.

Cache extraction retrieves current cache state. Used for SSR, persistence. Features: serialization, state transfer. Important for server rendering, cache backup.

Cache debugging through Apollo DevTools, logging. Inspect cache state, watch updates. Features: cache explorer, update tracking. Essential for development and troubleshooting.

Custom resolvers handle field computation, data transformation. Implement local-only fields, computed values. Features: field-level resolution, cache integration. Extends cache capabilities.

Real-time updates through subscriptions, cache updates. Implement automatic merging, optimistic UI. Features: subscription integration, cache consistency. Maintains real-time data state.

Cache pruning removes unused data. Implements automatic cleanup, reference tracking. Features: memory optimization, cache size management. Prevents cache bloat.

List updates through field policies, merge functions. Implement array operations, item updates. Features: automatic merging, custom ordering. Manages list-based data.

Cache hints provide caching instructions. Configure max-age, scope. Features: field-level control, cache behavior. Optimizes cache performance and freshness.

Cache preloading through initial state, prefetching. Implement data warming, startup data. Features: performance optimization, initial load. Improves application startup.

Cache manipulation through writeQuery, writeFragment. Implement direct updates, data modifications. Features: programmatic updates, cache control. Enables manual cache management.

Cache fragmentation through proper normalization, cleanup. Implement reference management, garbage collection. Features: performance optimization, memory management. Maintains cache efficiency.

Cache redirects customize data access paths. Implement field policies, custom resolvers. Features: data relationship handling, query optimization. Manages complex data access patterns.

Persistence strategies through storage options, update policies. Implement persistence plugins, recovery logic. Features: offline support, state preservation. Ensures data availability.

Nested object policies through type policies, merge functions. Implement relationship handling, nested updates. Features: complex data structures, reference management. Handles nested data effectively.

Cache warming through prefetching, initial data. Implement strategic loading, data preparation. Features: performance optimization, user experience. Improves application responsiveness.

Best practices include proper normalization, type policies, field policies. Implement efficient updates, proper cleanup. Features: performance optimization, maintainability. Ensures robust cache implementation.