Recursive / Nested Function Calls

Edge Functions can call other Edge Functions using fetch(). This enables powerful patterns like function chaining, fan-out/fan-in workflows, and recursive processing. To protect platform stability and prevent runaway amplification, Supabase rate limits these internal function-to-function calls.

What gets rate limited#

Rate limiting applies to outbound fetch() calls made by your Edge Functions to other Edge Functions within your project. This includes:

• Direct recursion: A function calling itself
• Function chaining: Function A calling Function B
• Circular calls: Function A calling Function B, which calls Function A
• Fan-out patterns: A function calling multiple other functions concurrently

Rate limit budget#

Each request chain has a budget of at least 5,000 requests per minute. In busier regions, this budget may be higher. All function-to-function calls within the same request chain share this budget.

For example, if Function A calls Function B, and Function B calls Function C, all three calls count toward the same budget pool.

Handling rate limit errors#

When the rate limit is exceeded, calling another Edge Function throws a RateLimitError. This error includes a retryAfterMs property indicating how long to wait (in milliseconds) before retrying. You should catch this error and handle it gracefully:

1
import { createClient } from 'jsr:@supabase/supabase-js@2'
2
3
const SUPABASE_PUBLISHABLE_KEYS = JSON.parse(Deno.env.get('SUPABASE_PUBLISHABLE_KEYS')!)
4
5
const supabase = createClient(
6
  Deno.env.get('SUPABASE_URL')!,
7
  // If you want to use a different api key, change 'default' to your preferred key name
8
  SUPABASE_PUBLISHABLE_KEYS['default']
9
)
10
11
Deno.serve(async (req) => {
12
  try {
13
    const { data, error } = await supabase.functions.invoke('other-function', {
14
      body: { foo: 'bar' },
15
    })
16
17
    if (error) throw error
18
19
    return new Response(JSON.stringify(data), {
20
      headers: { 'Content-Type': 'application/json' },
21
    })
22
  } catch (err) {
23
    if (err instanceof Deno.errors.RateLimitError) {
24
      // Use retryAfterMs to tell the client when to retry
25
      const retryAfterSeconds = Math.ceil(err.retryAfterMs / 1000)
26
      return new Response(
27
        JSON.stringify({ error: 'Service temporarily unavailable. Please retry later.' }),
28
        {
29
          status: 429,
30
          headers: {
31
            'Content-Type': 'application/json',
32
            'Retry-After': retryAfterSeconds.toString(),
33
          },
34
        }
35
      )
36
    }
37
    throw err
38
  }
39
})

You can also use retryAfterMs to implement automatic retries within your function:

1
import { createClient } from 'jsr:@supabase/supabase-js@2'
2
3
const SUPABASE_PUBLISHABLE_KEYS = JSON.parse(Deno.env.get('SUPABASE_PUBLISHABLE_KEYS')!)
4
5
const supabase = createClient(
6
  Deno.env.get('SUPABASE_URL')!,
7
  // If you want to use a different api key, change 'default' to your preferred key name
8
  SUPABASE_PUBLISHABLE_KEYS['default']
9
)
10
11
async function invokeWithRetry(functionName: string, payload: object, maxRetries = 3) {
12
  for (let attempt = 0; attempt < maxRetries; attempt++) {
13
    try {
14
      const { data, error } = await supabase.functions.invoke(functionName, {
15
        body: payload,
16
      })
17
      if (error) throw error
18
      return data
19
    } catch (err) {
20
      if (err instanceof Deno.errors.RateLimitError && attempt < maxRetries - 1) {
21
        // Wait for the recommended duration before retrying
22
        await new Promise((resolve) => setTimeout(resolve, err.retryAfterMs))
23
        continue
24
      }
25
      throw err
26
    }
27
  }
28
}

Tips for avoiding rate limits#

1. Batch operations instead of individual calls#

Instead of calling a function once per item, batch multiple items into a single call:

1
// ❌ Avoid: One call per item
2
for (const item of items) {
3
  await supabase.functions.invoke('process-item', { body: item })
4
}
5
6
// ✅ Better: Batch items into one call
7
await supabase.functions.invoke('process-items', { body: { items } })

2. Limit recursion depth#

If your function is recursive, set a maximum depth to prevent unbounded call chains:

1
Deno.serve(async (req) => {
2
  const { depth = 0, data } = await req.json()
3
4
  if (depth >= 5) {
5
    // Stop recursion at max depth
6
    return new Response(JSON.stringify({ result: data }))
7
  }
8
9
  // Process and recurse with incremented depth
10
  const processed = processData(data)
11
  const { data: result } = await supabase.functions.invoke('my-function', {
12
    body: { depth: depth + 1, data: processed },
13
  })
14
15
  return new Response(JSON.stringify(result))
16
})

3. Use queues for large workloads#

For processing large datasets, consider using Supabase Queues instead of recursive function calls. Queues handle backpressure automatically and are better suited for high-volume workloads.

4. Use shared libraries instead of separate functions#

Instead of creating separate Edge Functions that call each other, create a shared library of functions and import them directly. This avoids HTTP overhead and rate limits entirely:

1
// supabase/functions/_shared/transform.ts
2
export function validate(data: any) {
3
  // validation logic
4
}
5
6
export function transform(data: any) {
7
  // transformation logic
8
}
9
10
export async function save(data: any) {
11
  // save logic
12
}

1
// supabase/functions/process-data/index.ts
2
import { save, transform, validate } from '../_shared/transform.ts'
3
4
Deno.serve(async (req) => {
5
  const data = await req.json()
6
  const validated = validate(data)
7
  const transformed = transform(validated)
8
  const result = await save(transformed)
9
  return new Response(JSON.stringify(result))
10
})

5. Add delays for non-urgent processing#

If immediate processing isn't required, add delays between calls to spread the load:

1
async function processWithDelay(items: any[]) {
2
  for (const item of items) {
3
    await supabase.functions.invoke('process-item', { body: item })
4
    await new Promise((resolve) => setTimeout(resolve, 100)) // 100ms delay
5
  }
6
}

Common patterns and their impact#

Increasing rate limits#

Currently, all plans have the same rate limit budget. We are working on introducing custom limits for different use cases.

If you need a higher rate limit for your project, contact support with details about your use case.