GraphQL pagination with cursor-based and offset-based approaches

Pagination in GraphQL: Cursor-Based and Offset

GraphQL has two main pagination strategies: offset (LIMIT/OFFSET) and cursor-based (Relay Connection). Cursor-based works correctly when data changes between page requests, offset is simpler to implement and supports arbitrary page jumps.

Offset Pagination

Suitable for admin tables and lists with rare updates:

type Query {
  posts(limit: Int = 20, offset: Int = 0): PostList!
}

type PostList {
  items: [Post!]!
  total: Int!
  limit: Int!
  offset: Int!
  hasNextPage: Boolean!
}

const resolvers = {
  Query: {
    posts: async (parent, { limit = 20, offset = 0 }, context) => {
      // Limit maximum request size
      const safeLimit = Math.min(limit, 100)

      const [items, total] = await Promise.all([
        context.db.query(
          'SELECT * FROM posts ORDER BY created_at DESC LIMIT $1 OFFSET $2',
          [safeLimit, offset]
        ),
        context.db.queryOne('SELECT COUNT(*) as total FROM posts')
      ])

      return {
        items,
        total: parseInt(total.total),
        limit: safeLimit,
        offset,
        hasNextPage: offset + safeLimit < parseInt(total.total)
      }
    }
  }
}

Cursor-Based Pagination (Relay Connection)

Relay standard—the right choice for infinite scroll and frequently changing data:

type Query {
  posts(
    first: Int
    after: String
    last: Int
    before: String
    filter: PostFilter
  ): PostConnection!
}

type PostConnection {
  edges: [PostEdge!]!
  pageInfo: PageInfo!
  totalCount: Int!
}

type PostEdge {
  node: Post!
  cursor: String!
}

type PageInfo {
  hasNextPage: Boolean!
  hasPreviousPage: Boolean!
  startCursor: String
  endCursor: String
}

// Cursor is base64-encoded ID or timestamp
function encodeCursor(id) {
  return Buffer.from(`cursor:${id}`).toString('base64')
}

function decodeCursor(cursor) {
  const decoded = Buffer.from(cursor, 'base64').toString('utf8')
  const match = decoded.match(/^cursor:(.+)$/)
  return match ? match[1] : null
}

const resolvers = {
  Query: {
    posts: async (parent, { first = 20, after, last, before, filter }, context) => {
      const limit = Math.min(first || last || 20, 100)

      let query = 'SELECT * FROM posts'
      const params = []
      const conditions = []

      // Apply filters
      if (filter?.authorId) {
        params.push(filter.authorId)
        conditions.push(`author_id = $${params.length}`)
      }

      // Cursor condition
      if (after) {
        const afterId = decodeCursor(after)
        params.push(afterId)
        conditions.push(`id < $${params.length}`)  // for DESC order
      }

      if (before) {
        const beforeId = decodeCursor(before)
        params.push(beforeId)
        conditions.push(`id > $${params.length}`)
      }

      if (conditions.length) {
        query += ' WHERE ' + conditions.join(' AND ')
      }

      query += ' ORDER BY id DESC'

      // Request one extra to determine hasNextPage
      params.push(limit + 1)
      query += ` LIMIT $${params.length}`

      const rows = await context.db.query(query, params)
      const hasMore = rows.length > limit
      const items = hasMore ? rows.slice(0, limit) : rows

      const edges = items.map(row => ({
        node: row,
        cursor: encodeCursor(row.id)
      }))

      // Count total (only if requested—expensive operation)
      const totalCount = await context.db.queryOne(
        'SELECT COUNT(*) FROM posts'
      ).then(r => parseInt(r.count))

      return {
        edges,
        totalCount,
        pageInfo: {
          hasNextPage: after ? hasMore : false,
          hasPreviousPage: before ? hasMore : false,
          startCursor: edges[0]?.cursor ?? null,
          endCursor: edges[edges.length - 1]?.cursor ?? null
        }
      }
    }
  }
}

Cursor by Timestamp for Time Series

For data with non-unique order, use composite cursor:

// Cursor encodes (created_at, id)—two fields for unambiguous pagination
function encodeTimeCursor(createdAt, id) {
  return Buffer.from(JSON.stringify({ t: createdAt, id })).toString('base64')
}

function decodeTimeCursor(cursor) {
  try {
    return JSON.parse(Buffer.from(cursor, 'base64').toString())
  } catch {
    return null
  }
}

// SQL condition for composite cursor
// Exclude records with same timestamp but larger ID
const cursorCondition = after
  ? `(created_at < $1 OR (created_at = $1 AND id < $2))`
  : null

Client Usage (Apollo Client)

// Infinite scroll with fetchMore
const { data, fetchMore, loading } = useQuery(GET_POSTS, {
  variables: { first: 20 }
})

const loadMore = () => {
  const endCursor = data.posts.pageInfo.endCursor
  if (!endCursor || !data.posts.pageInfo.hasNextPage) return

  fetchMore({
    variables: { first: 20, after: endCursor },
    updateQuery: (prev, { fetchMoreResult }) => {
      if (!fetchMoreResult) return prev

      return {
        posts: {
          ...fetchMoreResult.posts,
          edges: [
            ...prev.posts.edges,
            ...fetchMoreResult.posts.edges
          ]
        }
      }
    }
  })
}

// With Apollo Client 3—InMemoryCache field policies
const cache = new InMemoryCache({
  typePolicies: {
    Query: {
      fields: {
        posts: relayStylePagination(['filter'])
      }
    }
  }
})

Strategy Comparison

Timelines

Implementing pagination (offset + cursor Relay Connection) for GraphQL API—1–2 working days.