Downloading Batch Export Files

---
name: downloading-batch-export-files
description: >
  Export PostHog events, persons, sessions, or the results of a HogQL query on demand and download the resulting
  files. Use when the user asks to download/export raw PostHog data, export HogQL query results, create a one-off
  file export, fetch a Parquet or JSONLines export, or use the file_download_batch_exports API.
  Covers starting the export with MCP, polling completion, and downloading via the existing REST redirect endpoint.
---

# Downloading batch export files

Use this skill when a user wants a one-off downloadable export of PostHog data.
The export is started and monitored through MCP, but the final file download uses the existing REST endpoint directly.

## Available MCP tools

| Tool                                           | Purpose                                                  |
| ---------------------------------------------- | -------------------------------------------------------- |
| `posthog:file-download-batch-exports-create`   | Start an on-demand export and return the run ID          |
| `posthog:file-download-batch-exports-retrieve` | Poll the run status and return file IDs after completion |

Do not rely on a generated MCP tool for the `/download/` endpoint.
That endpoint is a redirecting file download endpoint, so raw HTTP/download handling is the right interface until MCP has explicit redirect support.

## Workflow

### 1. Choose the export shape

Ask a short clarifying question if the user did not specify the required inputs:

- `model`: one of `events`, `persons`, `sessions`, or `hogql`
- `data_interval_start` and `data_interval_end`: ISO 8601 datetimes. Any supplied bound may not be in the future. When both bounds are supplied, they must be ordered and at most one week apart
  Required for `events`, `persons`, and `sessions`.
  For `hogql`, required only for the placeholders the query references. If only one placeholder is referenced, the other bound may be omitted and the one-week limit does not apply.
- `file.format`: `Parquet` or `JSONLines`; prefer `Parquet` for compact analytics exports and `JSONLines` for line-oriented text processing
- `file.compression`: optional, one of `zstd`, `gzip`, `brotli`, `lz4`, or `snappy`. If `JSONLines` was chosen as format, only `gzip` and `brotli` are supported.
- `file.max_size_mb`: part size in MiB, 1024 by default. A part can go a little over this size.
  Lower it when the user wants smaller parts, raise it for fewer and bigger ones, or set it to `null` to write a single file of any size.

For `events`, `include` and `exclude` are optional event-name filters.
Use them only when the user asks for specific events or wants to omit specific events.

For `hogql`, pass the query as `hogql_query` and leave out `include` and `exclude`.
You may prompt the user to export a slice of data by including a WHERE clause in the HogQL query, for example limiting results from the `events` table by bounding `timestamp`.
Always prefer limiting the data exported to the minimum necessary to solve the user's request.
Every column in the SELECT clause must be a field or have an alias.
This model is in closed beta and is enabled per team.

A `hogql` query can reference the `{data_interval_start}` and `{data_interval_end}` placeholders.
The export replaces them with the `data_interval_start` and `data_interval_end` values, so one query can export any interval.
Supply a bound for every placeholder the query references; a missing bound fails the request.
The bounds only replace placeholders and do not filter anything themselves, so a query without placeholders runs unchanged even when bounds are supplied.
Prefer placeholders over literal dates when the user wants a time range, or several consecutive ranges from the same query.
Compare with `>= {data_interval_start}` and `< {data_interval_end}`, so consecutive ranges do not export the same row twice.

### 2. Start the export

Call `posthog:file-download-batch-exports-create` with the selected shape.
The response contains an `id` for the export run.

Example request:

```json
{
  "model": "events",
  "file": {
    "format": "JSONLines",
    "compression": "gzip"
  },
  "include": ["$pageview"],
  "data_interval_start": "2026-05-25T00:00:00Z",
  "data_interval_end": "2026-05-26T00:00:00Z"
}
```

Example request for the `hogql` model:

```json
{
  "model": "hogql",
  "file": {
    "format": "Parquet"
  },
  "hogql_query": "SELECT event, timestamp, properties.$current_url AS url FROM events WHERE timestamp >= {data_interval_start} AND timestamp < {data_interval_end}",
  "data_interval_start": "2026-05-25T00:00:00Z",
  "data_interval_end": "2026-05-26T00:00:00Z"
}
```

### 3. Poll until completion

Call `posthog:file-download-batch-exports-retrieve` with the returned `id`.

Status handling:

| Status                                                                    | Action                                        |
| ------------------------------------------------------------------------- | --------------------------------------------- |
| `Starting` or `Running`                                                   | Wait briefly and poll again                   |
| `Completed`                                                               | Read the `files` array and download each file |
| `Cancelled`                                                               | Stop and report that the run was cancelled    |
| `Failed`, `FailedRetryable`, `FailedBilling`, `Terminated`, or `TimedOut` | Stop and report the `error` field             |

When `Completed`, the `files` array contains file UUIDs.
For single-file exports it usually contains one UUID.
For split exports, download every UUID unless the user asked for a specific part.

A `Completed` response also carries `records_completed`, the number of rows the run exported.
Report it to the user, because the count is otherwise only visible by opening every file.

### 4. Optionally, cancel a running export

If required by the user, a running export can be cancelled by calling `posthog:file-download-batch-exports-cancel-create` with the returned `id`.

An export that has already finished or has already failed may not be cancelled.

After cancelling an export, the `id` may not be used anymore and the export must start again from the beginning. However, you may still use the `id` to retrieve the export status (which will always be `Cancelled`).

### 5. Download files through REST

Use a direct authenticated HTTP request to the existing endpoint:

```text
GET /api/projects/{project_id}/file_download_batch_exports/{run_id}/download/{part}/
```

`part` can be either:

- a file UUID from the `files` array returned by `file-download-batch-exports-retrieve`
- a zero-based file index, ordered by key

If there is only one file, this also works without `part`:

```text
GET /api/projects/{project_id}/file_download_batch_exports/{run_id}/download/
```

Let the HTTP client follow the redirect, or inspect the `Location` header if you need the temporary signed URL.
Use the same PostHog authentication context as other API calls.

### 6. Save, do not print, file contents

Treat the result as a file download, not a chat response.
Parquet is binary and must be written as bytes.
JSONLines may still be large; save it to a file rather than pasting the contents unless the user explicitly asks for a tiny sample.

Use a filename that includes the model, run ID, and part identifier when possible, for example:

```text
posthog-events-<run_id>-<part>.jsonl.gz
posthog-persons-<run_id>-<part>.parquet
```

## Important notes

- The maximum export interval is one week. Split longer user requests into separate export runs or ask which week to export.
- The `hogql` model is in closed beta and is enabled per team. A permission error that says HogQL batch exports are not enabled means the team does not have the beta. Report that instead of retrying with a different query, and tell the user they can contact PostHog support to request access.
- The `hogql` model runs under stricter resource limits than the other models, because user queries are less predictable. If an export fails on memory, execution time, or bytes read, suggest narrowing the query with a WHERE clause instead of retrying it unchanged.
- The `hogql` model accepts an optional `hogql_modifiers` object. Each modifier in it overrides the project HogQL modifier with the same name for this export only, and the project modifiers apply to all others. By default, `timestamp` columns come out in the project timezone, so pass `{"convertToProjectTimezone": false}` when the user wants UTC timestamps. Pass the same `hogql_modifiers` to `posthog:file-download-batch-exports-count-rows-create`, so that the count matches the export.
- A run can briefly report `Running` after completion while file records are being created. Poll again instead of failing immediately.
- Download URLs are temporary. If a URL expires, call the REST download endpoint again for a fresh redirect.
- Do not send the signed URL to unrelated services unless the user explicitly asks; it grants temporary access to the exported file.
- If the user wants all parts of a split export, iterate over every UUID in `files`; do not assume part `0` is enough.
- Large batch exports may take a few minutes or even longer to complete. Suggest to the user that they can speed-up their download by including only certain events or narrowing the date range.