# How to Handle Long Polling Offset Management in Telego

> Learn how Telego automatically handles long polling offset management ensuring no duplicate updates are received through its internal counter system.

- Repository: [Artem Yadelskyi/telego](https://github.com/mymmrac/telego)
- Tags: how-to-guide
- Published: 2026-03-07

---

**Telego automatically manages the `offset` parameter for Telegram's `getUpdates` method by incrementing the internal counter to `UpdateID + 1` after processing each batch, ensuring no duplicate updates are received.**

The `offset` parameter is critical for long-polling in the Telegram Bot API, telling the server which updates you've already processed. In Telego, the Go library for Telegram bots, this offset management is handled automatically within the `UpdatesViaLongPolling` method, though developers can override this behavior when persisting state across restarts.

## How Telego Manages the Offset Automatically

Telego's long-polling implementation tracks the `offset` parameter internally so you don't have to calculate it manually. The core logic lives in [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go) within the `UpdatesViaLongPolling` and `doLongPolling` functions.

### The UpdatesViaLongPolling Entry Point

When you initiate long polling, `UpdatesViaLongPolling` creates a copy of your `GetUpdatesParams` (or uses defaults if you pass `nil`) and launches `doLongPolling` in a separate goroutine. This design ensures that the offset state is maintained throughout the bot's lifecycle.

```go
// From long_polling.go lines 68-78
updates := &UpdatesViaLongPolling{
    bot:    b,
    params: *params, // Copy of params with offset
    // ... other fields
}
go updates.doLongPolling(ctx)

```

### The Internal doLongPolling Loop

Inside `doLongPolling`, every batch returned by `Bot.GetUpdates` is processed sequentially. For each update whose `UpdateID` is greater than or equal to the current `params.Offset`, the offset is advanced to `UpdateID + 1`. This increment happens immediately after the update is received, ensuring that Telegram never sends that update again.

```go
// From long_polling.go lines 38-40
if upd.UpdateID >= params.Offset {
    params.Offset = upd.UpdateID + 1
}

```

This mechanism works because Telegram's `getUpdates` method only returns updates with an `update_id` strictly greater than the supplied `offset` parameter. By setting `params.Offset` to the last processed ID plus one, Telego guarantees exactly-once delivery semantics for your bot handlers.

## When to Manually Control the Offset

While automatic offset management handles most use cases, there are scenarios where you need to intervene:

- **Standard usage**: Simply call `UpdatesViaLongPolling` with `params` set to `nil` or only specify `Timeout`. Telego updates the offset internally; you do not need to manage it.
- **Persisting progress**: When restarting your bot, you want to avoid re-processing old updates. Store the latest `offset` (e.g., in a file or database) after each update and supply it on the next start via `GetUpdatesParams{Offset: savedOffset}`.
- **Skipping updates**: If you need to ignore a specific range of historical updates, initialize `params.Offset` with the desired starting ID before calling `UpdatesViaLongPolling`. The internal loop will continue from that point.

## Configuration Options for Long Polling

Telego provides several functional options to customize the polling behavior in [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go):

- **`WithLongPollingUpdateInterval`** – Adds a pause between successive `GetUpdates` calls, useful for respecting rate limits or reducing server load.
- **`WithLongPollingRetryTimeout`** – Sets the wait time before retrying after a network or API error.
- **`WithLongPollingBuffer`** – Defines the size of the buffered channel that receives updates, controlling backpressure.

## Practical Code Examples

### Basic Long Polling with Automatic Offset

For most bots, simply start the long poller and let Telego handle the offset:

```go
ctx := context.Background()
bot, err := telego.NewBot("YOUR_BOT_TOKEN", telego.WithDefaultDebugLogger())
if err != nil {
    log.Fatal(err)
}

updates, err := bot.UpdatesViaLongPolling(ctx, nil) // nil uses defaults & auto offset
if err != nil {
    log.Fatal(err)
}

for update := range updates {
    fmt.Printf("Processing update %d from chat %d\n", 
        update.UpdateID, update.Message.Chat.ID)
}

```

Telego automatically increments the offset after each update, ensuring you never receive duplicates.

### Persisting Offset Between Restarts

To avoid processing the same updates after a bot restart, persist the offset to storage:

```go
// Helper functions to implement based on your storage (file, Redis, etc.)
func loadOffsetFromFile() int64 { /* ... */ return 0 }
func saveOffsetToFile(offset int64) { /* ... */ }

func main() {
    ctx := context.Background()
    bot, _ := telego.NewBot("TOKEN")
    
    // Load previous state
    savedOffset := loadOffsetFromFile()
    
    params := &telego.GetUpdatesParams{
        Offset:  savedOffset,
        Timeout: 8,
    }
    
    updates, _ := bot.UpdatesViaLongPolling(ctx, params)
    
    for upd := range updates {
        handleUpdate(upd)
        
        // Persist next expected offset (current ID + 1)
        saveOffsetToFile(upd.UpdateID + 1)
    }
}

```

This pattern ensures that even if the bot crashes, it resumes from the correct position without missing or duplicating messages.

### Custom Polling Intervals and Error Handling

Control the polling behavior to respect rate limits or handle network instability:

```go
updates, err := bot.UpdatesViaLongPolling(
    ctx,
    &telego.GetUpdatesParams{Timeout: 10},
    telego.WithLongPollingUpdateInterval(2*time.Second), // 2s pause between polls
    telego.WithLongPollingRetryTimeout(5*time.Second),   // 5s wait after errors
    telego.WithLongPollingBuffer(100),                   // Buffer 100 updates
)
if err != nil {
    log.Fatal(err)
}

```

These options help prevent hitting Telegram API limits and provide resilience against temporary network failures.

## Key Source Files and Implementation Details

Understanding the source structure helps when debugging or extending Telego's behavior:

| File | Purpose | Link |
|------|---------|------|
| [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go) | Core long-polling logic, offset handling, and configuration options | [Source](https://github.com/mymmrac/telego/blob/main/long_polling.go) |
| [`methods.go`](https://github.com/mymmrac/telego/blob/main/methods.go) | Defines `GetUpdatesParams` struct including the `Offset` field | [Source](https://github.com/mymmrac/telego/blob/main/methods.go) |
| [`examples/updates_long_polling/main.go`](https://github.com/mymmrac/telego/blob/main/examples/updates_long_polling/main.go) | Working example demonstrating automatic offset management | [Source](https://github.com/mymmrac/telego/blob/main/examples/updates_long_polling/main.go) |
| [`bot.go`](https://github.com/mymmrac/telego/blob/main/bot.go) | Contains runner management to prevent concurrent polling/webhook conflicts | [Source](https://github.com/mymmrac/telego/blob/main/bot.go) |

The offset logic specifically resides in the `doLongPolling` method within [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go), where the comparison `if upd.UpdateID >= params.Offset` ensures that only new updates advance the counter.

## Summary

- **Telego handles offsets automatically** through the `UpdatesViaLongPolling` method, incrementing the internal counter to `UpdateID + 1` after each processed update.
- **Manual intervention is only needed** when persisting state across restarts or when intentionally skipping historical updates.
- **Key implementation** resides in [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go), specifically within the `doLongPolling` loop that checks `upd.UpdateID >= params.Offset`.
- **Configuration options** like `WithLongPollingUpdateInterval` and `WithLongPollingRetryTimeout` provide control over polling frequency and error resilience.
- **Persistence pattern** involves storing `update.UpdateID + 1` after each message and supplying it as `GetUpdatesParams.Offset` on the next startup.

## Frequently Asked Questions

### Does Telego require manual offset management?

No. By default, Telego automatically manages the `offset` parameter when you use `UpdatesViaLongPolling`. The library maintains an internal counter in [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go) that advances to `UpdateID + 1` after each update is received, ensuring Telegram never sends duplicates. You only need to manually specify an offset when persisting state across bot restarts or when intentionally skipping historical messages.

### How do I persist the offset across bot restarts?

To avoid re-processing updates after a restart, store the latest offset value after each update and supply it when initializing the bot. Implement a storage mechanism (file, database, or cache) to save `update.UpdateID + 1` after processing each message. On startup, load this value and pass it as `GetUpdatesParams.Offset`. According to the implementation in [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go), Telego will resume from this position and continue automatic management from there.

### What happens if I provide a custom offset?

When you initialize `UpdatesViaLongPolling` with a `GetUpdatesParams` struct containing a specific `Offset` value, Telego starts polling from that update ID. The internal `doLongPolling` loop in [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go) compares each incoming update's `UpdateID` against your provided offset, only processing updates where `UpdateID >= params.Offset`. After processing begins, Telego automatically increments the offset internally, so your manual setting only affects the starting position.

### How does Telego prevent duplicate updates?

Telego implements an exact-once delivery guarantee for updates within a single polling session by strictly adhering to Telegram's offset semantics. In [`long_polling.go`](https://github.com/mymmrac/telego/blob/main/long_polling.go), the `doLongPolling` method checks each update against the current `params.Offset` and immediately advances the offset to `UpdateID + 1` before the update is dispatched to your handler channel. Since Telegram's `getUpdates` method only returns updates with IDs strictly greater than the provided offset, this incremental approach ensures that once an update ID is acknowledged, it will never be fetched again, even if the bot restarts (provided you persist the offset).