# Transformer Pub/Sub configuration reference > Configure Transformer Pub/Sub with stream settings, GCS output, windowing, and monitoring for GCP real-time transformation. > Source: https://docs.snowplow.io/docs/api-reference/loaders-storage-targets/snowplow-rdb-loader/transforming-enriched-data/stream-transformer/transformer-pubsub/configuration-reference/ > Documentation index: https://docs.snowplow.io/llms.txt The configuration reference in this page is written for Transformer Pubsub `6.10.0` An example of the minimal required config for the Transformer Pubsub can be found [here](https://github.com/snowplow/snowplow-rdb-loader/tree/master/config/transformer/gcp/transformer.pubsub.config.minimal.hocon) and a more detailed one [here](https://github.com/snowplow/snowplow-rdb-loader/tree/master/config/transformer/gcp/transformer.pubsub.config.reference.hocon). ## License Since version 6.0.0, RDB Loader is released under the [Snowplow Limited Use License](/limited-use-license-1.0/) ([FAQ](/docs/licensing/limited-use-license-faq/)). To accept the terms of license and run RDB Loader, set the `ACCEPT_LIMITED_USE_LICENSE=yes` environment variable. Alternatively, you can configure the `license.accept` option, like this: ```hocon license: { accept: true } ``` | Parameter | Description | | ---------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `input.subscription` | Name of the Pubsub subscription with the enriched events | | `input.parallelPullCount` | Optional. Default value 1. Number of threads used internally by permutive library to handle incoming messages. These threads do very little "work" apart from writing the message to a concurrent Queue. | | `input.bufferSize` | Optional. Default value 500. The max size of the buffer queue used between fs2-pubsub and java-pubsub libraries. | | `input.maxAckExtensionPeriod` | Optional. Default value '1 hour'. The maximum period a message ack deadline will be extended. | | `output.path` | Required. GCS URI of the transformed output. It needs to have `gs://` URI scheme | | `output.compression` | Optional. One of `NONE` or `GZIP`. The default is `GZIP`. | | `output.bufferSize` | Optional. Default value 4096. During the window period, processed items are stored in a buffer. This value determines the size of this buffer. When its limit is reached, buffer content is flushed to blob storage. | | `output.maxRecordsPerFile` (since 5.4.0) | Optional. Default = 10000. Max number of events per parquet partition. | | `output.bad.type` (since 5.4.0) | Optional. Either `pubsub` or `file`, default value `file`. Type of bad output sink. When `file`, failed events are written as files under URI configured in `output.path`. | | `output.bad.topic` (since 5.4.0) | Required if output type is `pubsub`. Name of the PubSub topic that will receive the bad data. | | `output.bad.batchSize` (since 5.4.0) | Optional. Default = 1000, max = 1000. Maximum number of messages sent to PubSub within a batch. When the buffer reaches this number of messages they are sent. | | `output.bad.requestByteThreshold` (since 5.4.0) | Optional. Default = 8000000, max = 10MB. Maximum number of bytes sent to PubSub within a batch. When the buffer reaches this size messages are sent. | | `output.bad.delayThreshold` (since 5.4.0) | Optional. Default = 200 milliseconds. Delay threshold to use for PubSub batching. After this amount of time has elapsed, before `batchSize` and `requestByteThreshold` have been reached, messages from the buffer will be sent. | | `queue.topic` | Name of the Pubsub topic used to communicate with Loader | | `formats.fileFormat` | Optional. The default option at the moment is `JSON`. Either `JSON` or `PARQUET`. | | `windowing` | Optional. Frequency to emit shredding complete message. The default is `5 minutes`. Note that there is a problem with acking messages when window period is greater than 10 minute in transformer-pubsub. Therefore, it is advisable to make window period equal or less than 10 minutes. | | `monitoring.metrics.*` | Send metrics to a StatsD server or stdout. | | `monitoring.metrics.statsd.*` | Optional. For sending metrics (good and bad event counts) to a StatsD server. | | `monitoring.metrics.statsd.hostname` | Required if `monitoring.metrics.statsd` section is configured. The host name of the StatsD server. | | `monitoring.metrics.statsd.port` | Required if `monitoring.metrics.statsd` section is configured. Port of the StatsD server. | | `monitoring.metrics.statsd.tags` | Optional. Tags which are used to annotate the StatsD metric with any contextual information. | | `monitoring.metrics.statsd.prefix` | Optional. Configures the prefix of StatsD metric names. The default is `snoplow.transformer`. | | `monitoring.metrics.stdout.*` | Optional. For sending metrics to stdout. | | `monitoring.metrics.stdout.prefix` | Optional. Overrides the default metric prefix. | | `telemetry.disable` | Optional. Set to `true` to disable [telemetry](/docs/get-started/self-hosted/telemetry/). | | `telemetry.userProvidedId` | Optional. See [here](/docs/get-started/self-hosted/telemetry/#how-can-i-help) for more information. | | `monitoring.sentry.dsn` | Optional. For tracking runtime exceptions. | | `featureFlags.enableMaxRecordsPerFile` (since 5.4.0) | Optional, default = true. When enabled, `output.maxRecordsPerFile` configuration parameter is going to be used. | | `validations.*` | Optional. Criteria to validate events against | | `validations.minimumTimestamp` | This is currently the only validation criterion. It checks that all timestamps in the event are older than a specific point in time, eg `2021-11-18T11:00:00.00Z`. | | `featureFlags.*` | Optional. Enable features that are still in beta, or which aim to enable smoother upgrades. | | `featureFlags.legacyMessageFormat` | This currently the only feature flag. Setting this to `true` allows you to use a new version of the transformer with an older version of the loader. | | `featureFlags.truncateAtomicFields` (since 5.4.0) | Optional, default `false`. When enabled, event's atomic fields are truncated (based on the length limits from the atomic JSON schema) before transformation. |