TanStack/db @tanstack/db@0.4.19

on GitHub

Patch Changes

• Significantly improve localStorage collection performance during rapid mutations (#760)

  Optimizes localStorage collections to eliminate redundant storage reads, providing dramatic performance improvements for use cases with rapid mutations (e.g., text input with live query rendering).

  Performance Improvements:

  • 67% reduction in localStorage I/O operations - from 3 reads + 1 write per mutation down to just 1 write
  • Eliminated 2 JSON parse operations per mutation
  • Eliminated 1 full collection diff operation per mutation
  • Leverages in-memory cache (lastKnownData) instead of reading from storage on every mutation

  What Changed:

  1. Mutation handlers now use in-memory cache instead of loading from storage before mutations
  2. Post-mutation sync eliminated - no longer triggers redundant storage reads after local mutations
  3. Manual transactions (acceptMutations) optimized to use in-memory cache

  Before: Each mutation performed 3 I/O operations:

  • loadFromStorage() - read + JSON parse
  • Modify data
  • saveToStorage() - JSON stringify + write
  • processStorageChanges() - another read + parse + diff

  After: Each mutation performs 1 I/O operation:

  • Modify in-memory data ✨ No I/O!
  • saveToStorage() - JSON stringify + write

  Safety:

  • Cross-tab synchronization still works correctly via storage event listeners
  • All 50 tests pass including 8 new tests specifically for rapid mutations and edge cases
  • 92.3% code coverage on local-storage.ts
  • lastKnownData cache kept in sync with storage through initial load, mutations, and cross-tab events

  This optimization is particularly impactful for applications with:

  • Real-time text input with live query rendering
  • Frequent mutations to localStorage-backed collections
  • Multiple rapid sequential mutations