Tanstack Db

by tanstack-skills6f5521ecbdfbNo license35 starsListed Oct 8, 2026Updated Oct 8, 2026Repository updated 8 months ago

Reactive client-first store for your API with collections, live queries, and optimistic mutations.

Instructions onlySoftware Development

AI-generated overview

Reference guide for TanStack DB, a client-side reactive store with collections, live queries and optimistic mutations.

What it does: This skill is a documentation-style reference for TanStack DB, a client-side embedded database layer built on differential dataflow. It explains collections, sync modes, live queries with a SQL-like builder, joins, filter operators, optimistic mutations and query-driven sync, with TypeScript code examples throughout. It also lists performance figures, supported collection types, best practices and common pitfalls.
When to use it: Use it when working with TanStack DB in a frontend project and needing guidance on setting up collections, writing live queries or handling optimistic mutations. It is also useful for choosing a sync mode or mapping query predicates to API parameters.
Requirements: No scripts are shipped; it is instructions only. Applying the examples assumes a JavaScript/TypeScript project with the @tanstack/react-db, @tanstack/query-db-collection and @tanstack/db packages installed, plus an API or data source to sync with.

Overview

TanStack DB is a client-side embedded database layer built on differential dataflow. It maintains normalized collections, uses incremental computation for live queries, provides automatic optimistic mutations, and integrates with TanStack Query for data fetching. Sub-millisecond updates even with 100k+ rows.

Package: @tanstack/react-db Query Integration: @tanstack/query-db-collection Status: Beta (v0.5)

Installation

Core Concepts

Collections: Normalized data stores wrapping data sources (TanStack Query, Electric, etc.)
Live Queries: Reactive subscriptions with SQL-like query builder
Optimistic Mutations: Automatic instant UI updates with rollback on failure
Differential Dataflow: Only recomputes affected query results on changes

Collections

Creating a Collection

typescript

import { createCollection } from '@tanstack/react-db'import { queryCollectionOptions } from '@tanstack/query-db-collection'
const todoCollection = createCollection(  queryCollectionOptions({    queryKey: ['todos'],    queryFn: async () => api.todos.getAll(),    getKey: (item) => item.id,    schema: todoSchema,    onInsert: async ({ transaction }) => {      await Promise.all(        transaction.mutations.map((mutation) =>          api.todos.create(mutation.modified)        )      )    },    onUpdate: async ({ transaction }) => {      await Promise.all(        transaction.mutations.map((mutation) =>          api.todos.update(mutation.modified)        )      )    },    onDelete: async ({ transaction }) => {      await Promise.all(        transaction.mutations.map((mutation) =>          api.todos.delete(mutation.original.id)        )      )    },  }))

import { createCollection } from '@tanstack/react-db'import { queryCollectionOptions } from '@tanstack/query-db-collection'
const todoCollection = createCollection(  queryCollectionOptions({    queryKey: ['todos'],    queryFn: async () => api.todos.getAll(),    getKey: (item) => item.id,    schema: todoSchema,    onInsert: async ({ transaction }) => {      await Promise.all(        transaction.mutations.map((mutation) =>          api.todos.create(mutation.modified)        )      )    },    onUpdate: async ({ transaction }) => {      await Promise.all(        transaction.mutations.map((mutation) =>          api.todos.update(mutation.modified)        )      )    },    onDelete: async ({ transaction }) => {      await Promise.all(        transaction.mutations.map((mutation) =>          api.todos.delete(mutation.original.id)        )      )    },  }))

Sync Modes

typescript

// Eager (default): Load entire collection upfront. Best for <10k rows.const smallCollection = createCollection(  queryCollectionOptions({ syncMode: 'eager', /* ... */ }))
// On-Demand: Load only what queries request. Best for >50k rows, search.const largeCollection = createCollection(  queryCollectionOptions({    syncMode: 'on-demand',    queryFn: async (ctx) => {      const params = parseLoadSubsetOptions(ctx.meta?.loadSubsetOptions)      return api.getProducts(params)    },  }))
// Progressive: Load query subset immediately, full sync in background.const collaborativeCollection = createCollection(  queryCollectionOptions({ syncMode: 'progressive', /* ... */ }))

// Eager (default): Load entire collection upfront. Best for <10k rows.const smallCollection = createCollection(  queryCollectionOptions({ syncMode: 'eager', /* ... */ }))
// On-Demand: Load only what queries request. Best for >50k rows, search.const largeCollection = createCollection(  queryCollectionOptions({    syncMode: 'on-demand',    queryFn: async (ctx) => {      const params = parseLoadSubsetOptions(ctx.meta?.loadSubsetOptions)      return api.getProducts(params)    },  }))
// Progressive: Load query subset immediately, full sync in background.const collaborativeCollection = createCollection(  queryCollectionOptions({ syncMode: 'progressive', /* ... */ }))

Live Queries

Basic Query

typescript

import { useLiveQuery } from '@tanstack/react-db'import { eq } from '@tanstack/db'
function TodoList() {  const { data: todos } = useLiveQuery((query) =>    query      .from({ todos: todoCollection })      .where(({ todos }) => eq(todos.completed, false))  )
  return <ul>{todos.map(todo => <li key={todo.id}>{todo.text}</li>)}</ul>}

import { useLiveQuery } from '@tanstack/react-db'import { eq } from '@tanstack/db'
function TodoList() {  const { data: todos } = useLiveQuery((query) =>    query      .from({ todos: todoCollection })      .where(({ todos }) => eq(todos.completed, false))  )
  return <ul>{todos.map(todo => <li key={todo.id}>{todo.text}</li>)}</ul>}

Query Builder API

typescript

const { data } = useLiveQuery((q) =>  q    .from({ t: todoCollection })    .where(({ t }) => eq(t.status, 'active'))    .orderBy(({ t }) => t.createdAt, 'desc')    .limit(10))

const { data } = useLiveQuery((q) =>  q    .from({ t: todoCollection })    .where(({ t }) => eq(t.status, 'active'))    .orderBy(({ t }) => t.createdAt, 'desc')    .limit(10))

Joins

typescript

const { data } = useLiveQuery((q) =>  q    .from({ t: todoCollection })    .innerJoin(      { u: userCollection },      ({ t, u }) => eq(t.userId, u.id)    )    .innerJoin(      { p: projectCollection },      ({ u, p }) => eq(u.projectId, p.id)    )    .where(({ p }) => eq(p.id, currentProject.id)))

const { data } = useLiveQuery((q) =>  q    .from({ t: todoCollection })    .innerJoin(      { u: userCollection },      ({ t, u }) => eq(t.userId, u.id)    )    .innerJoin(      { p: projectCollection },      ({ u, p }) => eq(u.projectId, p.id)    )    .where(({ p }) => eq(p.id, currentProject.id)))

Filter Operators

typescript

import { eq, lt, and } from '@tanstack/db'
// Equalityeq(field, value)
// Less thanlt(field, value)
// ANDand(eq(product.category, 'electronics'), lt(product.price, 100))

import { eq, lt, and } from '@tanstack/db'
// Equalityeq(field, value)
// Less thanlt(field, value)
// ANDand(eq(product.category, 'electronics'), lt(product.price, 100))

With Ordering and Limits

typescript

const { data } = useLiveQuery((q) =>  q    .from({ product: productsCollection })    .where(({ product }) =>      and(eq(product.category, 'electronics'), lt(product.price, 100))    )    .orderBy(({ product }) => product.price, 'asc')    .limit(10))

const { data } = useLiveQuery((q) =>  q    .from({ product: productsCollection })    .where(({ product }) =>      and(eq(product.category, 'electronics'), lt(product.price, 100))    )    .orderBy(({ product }) => product.price, 'asc')    .limit(10))

Optimistic Mutations

Insert

typescript

todoCollection.insert({  id: uuid(),  text: 'New todo',  completed: false,})// Immediately: updates all live queries referencing this collection// Background: calls onInsert handler to sync with server// On failure: automatic rollback

todoCollection.insert({  id: uuid(),  text: 'New todo',  completed: false,})// Immediately: updates all live queries referencing this collection// Background: calls onInsert handler to sync with server// On failure: automatic rollback

No Manual Boilerplate

Query-Driven Sync (On-Demand)

Live queries automatically generate optimized network requests:

typescript

// This live query...useLiveQuery((q) =>  q.from({ product: productsCollection })    .where(({ product }) => and(eq(product.category, 'electronics'), lt(product.price, 100)))    .orderBy(({ product }) => product.price, 'asc')    .limit(10))
// ...automatically generates:// GET /api/products?category=electronics&price_lt=100&sort=price:asc&limit=10

// This live query...useLiveQuery((q) =>  q.from({ product: productsCollection })    .where(({ product }) => and(eq(product.category, 'electronics'), lt(product.price, 100)))    .orderBy(({ product }) => product.price, 'asc')    .limit(10))
// ...automatically generates:// GET /api/products?category=electronics&price_lt=100&sort=price:asc&limit=10

Predicate Mapping

typescript

queryFn: async (ctx) => {  const { filters, sorts, limit } = parseLoadSubsetOptions(ctx.meta?.loadSubsetOptions)
  const params = new URLSearchParams()  filters.forEach(({ field, operator, value }) => {    if (operator === 'eq') params.set(field.join('.'), String(value))    else if (operator === 'lt') params.set(`${field.join('.')}_lt`, String(value))  })  if (limit) params.set('limit', String(limit))
  return fetch(`/api/products?${params}`).then(r => r.json())}

queryFn: async (ctx) => {  const { filters, sorts, limit } = parseLoadSubsetOptions(ctx.meta?.loadSubsetOptions)
  const params = new URLSearchParams()  filters.forEach(({ field, operator, value }) => {    if (operator === 'eq') params.set(field.join('.'), String(value))    else if (operator === 'lt') params.set(`${field.join('.')}_lt`, String(value))  })  if (limit) params.set('limit', String(limit))
  return fetch(`/api/products?${params}`).then(r => r.json())}

Performance

Supported Collection Types

Query Collection - TanStack Query integration
Electric Collection - Electric SQL real-time sync
TrailBase Collection - TrailBase backend
RxDB Collection - RxDB integration
PowerSync Collection - PowerSync sync
LocalStorage Collection - Browser persistence
LocalOnly Collection - In-memory only

API Summary

typescript

import { createCollection, useLiveQuery } from '@tanstack/react-db'import { queryCollectionOptions } from '@tanstack/query-db-collection'import { eq, lt, and, parseLoadSubsetOptions } from '@tanstack/db'

import { createCollection, useLiveQuery } from '@tanstack/react-db'import { queryCollectionOptions } from '@tanstack/query-db-collection'import { eq, lt, and, parseLoadSubsetOptions } from '@tanstack/db'

Best Practices

Define collections at module level - they're singletons
Choose the right sync mode: eager (<10k), on-demand (>50k), progressive (collaborative)
Use joins instead of view-specific APIs - load normalized collections once
Let TanStack Query handle fetching - DB augments Query, doesn't replace it
Use parseLoadSubsetOptions to map live query predicates to API params
Rely on automatic optimistic updates - don't manually manage optimistic state
Use schemas for runtime validation and TypeScript inference
Leverage incremental computation - let the engine handle filtering vs manual .filter()

Common Pitfalls

Creating collections inside components (should be module-level)
Trying to replace TanStack Query entirely (DB builds on top of it)
Using manual .filter() in render instead of live query where clauses
Not providing getKey for proper normalization
Forgetting mutation handlers (onInsert, onUpdate, onDelete) for server sync

Source and attribution

Source:tanstack-skills/tanstack-skillsinplugins/tanstack-db/skills/tanstack-dbat commit6f5521e

License: No license

Content belongs to its original authors. SourceWeft indexes it from a public repository.

Report or request removal

Before (TanStack Query only)	After (TanStack DB)
Manual `onMutate` for optimistic state	Automatic
Manual `onError` rollback logic	Automatic
Per-mutation cache invalidation	All live queries update automatically

Operation	Latency
Single row update (100k sorted collection)	~0.7 ms
Subsequent queries (after sync)	<1 ms
Join across collections	Sub-millisecond

Tanstack Db

Overview

Installation

Core Concepts

Collections

Creating a Collection

Sync Modes

Live Queries

Basic Query

Query Builder API

Joins

Filter Operators

With Ordering and Limits

Optimistic Mutations

Insert

No Manual Boilerplate

Query-Driven Sync (On-Demand)

Predicate Mapping

Performance

Supported Collection Types

API Summary

Best Practices

Common Pitfalls

Source and attribution

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