apache-pulsar.md

description
This guide shows you how to ingest a stream of records from an Apache Pulsar topic into a Pinot table.

Import from Apache Pulsar

Pinot supports consuming data from Apache Pulsar via the pinot-pulsar plugin. You need to enable this plugin so that Pulsar specific libraries are present in the classpath.

Enable the Pulsar plugin with the following config at the time of Pinot setup: -Dplugins.include=pinot-pulsar

{% hint style="info" %} The pinot-pulsar plugin is not part of official 0.10.0 binary. You can download the plugin from our external repository and add it to the libs or plugins directory in pinot. {% endhint %}

Set up Pulsar table

Here is a sample Pulsar stream config. You can use the streamConfigs section from this sample and make changes for your corresponding table.

{
  "tableName": "pulsarTable",
  "tableType": "REALTIME",
  "segmentsConfig": {
    "timeColumnName": "timestamp",
    "replicasPerPartition": "1"
  },
  "tenants": {},
  "tableIndexConfig": {
    "loadMode": "MMAP",
    "streamConfigs": {
      "streamType": "pulsar",
      "stream.pulsar.topic.name": "<your pulsar topic name>",
      "stream.pulsar.bootstrap.servers": "pulsar://localhost:6650,pulsar://localhost:6651",
      "stream.pulsar.consumer.prop.auto.offset.reset" : "smallest",
      "stream.pulsar.consumer.type": "lowlevel",
      "stream.pulsar.fetch.timeout.millis": "30000",
      "stream.pulsar.decoder.class.name": "org.apache.pinot.plugin.inputformat.json.JSONMessageDecoder",
      "stream.pulsar.consumer.factory.class.name": "org.apache.pinot.plugin.stream.pulsar.PulsarConsumerFactory",
      "realtime.segment.flush.threshold.rows": "1000000",
      "realtime.segment.flush.threshold.time": "6h"
    }
  },
  "metadata": {
    "customConfigs": {}
  }
}

Pulsar configuration options

You can change the following Pulsar specifc configurations for your tables

Property	Description
streamType	This should be set to "pulsar"
stream.pulsar.topic.name	Your pulsar topic name
stream.pulsar.bootstrap.servers	Comma-separated broker list for Apache Pulsar
stream.pulsar.metadata.populate	set to true to populate metadata
stream.pulsar.metadata.fields	set to comma separated list of metadata fields

Authentication

The Pinot-Pulsar connector supports authentication using security tokens. To generate a token, follow the instructions in Pulsar documentation. Once generated, add the following property to streamConfigs to add an authentication token for each request:

"stream.pulsar.authenticationToken":"your-auth-token"

OAuth2 Authentication

The Pinot-Pulsar connector supports authentication using OAuth2, for example, if connecting to a StreamNative Pulsar cluster. For more information, see how to Configure OAuth2 authentication in Pulsar clients. Once configured, you can add the following properties to streamConfigs:

"stream.pulsar.issuerUrl": "https://auth.streamnative.cloud"
"stream.pulsar.credsFilePath": "file:///path/to/private_creds_file
"stream.pulsar.audience": "urn:sn:pulsar:test:test-cluster"

TLS support

The Pinot-pulsar connector also supports TLS for encrypted connections. You can follow the official pulsar documentation to enable TLS on your pulsar cluster. Once done, you can enable TLS in pulsar connector by providing the trust certificate file location generated in the previous step.

"stream.pulsar.tlsTrustCertsFilePath": "/path/to/ca.cert.pem"

Also, make sure to change the brokers url from pulsar://localhost:6650 to pulsar+ssl://localhost:6650 so that secure connections are used.

For other table and stream configurations, you can headover to Table configuration Reference

Supported Pulsar versions

Pinot currently relies on Pulsar client version 2.7.2. Make sure the Pulsar broker is compatible with the this client version.

Extract record headers as Pinot table columns

Pinot's Pulsar connector supports automatically extracting record headers and metadata into the Pinot table columns. Pulsar supports a large amount of per-record metadata. Reference the official Pulsar documentation for the meaning of the metadata fields.

The following table shows the mapping for record header/metadata to Pinot table column names:

Pulsar Message	Pinot table Column	Comments	Available By Default
key : String	__key : String		Yes
properties : Map<String, String>	Each header key is listed as a separate column: __header$HeaderKeyName : String		Yes
publishTime : Long	__metadata$publishTime : String	publish time as determined by the producer	Yes
brokerPublishTime: Optional	__metadata$brokerPublishTime : String	publish time as determined by the broker	Yes
eventTime : Long	__metadata$eventTime : String		Yes
messageId : MessageId -> String	__metadata$messageId : String	String representation of the MessagId field. The format is ledgerId:entryId:partitionIndex
messageId : MessageId -> bytes	__metadata$messageBytes : String	Base64 encoded version of the bytes returned from calling MessageId.toByteArray()
producerName : String	__metadata$producerName : String
schemaVersion : byte[]	__metadata$schemaVersion : String	Base64 encoded value
sequenceId : Long	__metadata$sequenceId : String
orderingKey : byte[]	__metadata$orderingKey : String	Base64 encoded value
size : Integer	__metadata$size : String
topicName : String	__metadata$topicName : String
index : String	__metadata$index : String
redeliveryCount : Integer	__metadata$redeliveryCount : String

In order to enable the metadata extraction in a Pulsar table, set the stream config metadata.populate to true. The fields eventTime, publishTime, brokerPublishTime, and key are populated by default. If you would like to extract additional fields from the Pulsar Message, populate the metadataFields config with a comma separated list of fields to populate. The fields are referenced by the field name in the Pulsar Message. For example, setting:

"streamConfigs": {
  ...
        "stream.pulsar.metadata.populate": "true",
        "stream.pulsar.metadata.fields": "messageId,messageIdBytes,eventTime,topicName",
  ...
}

Will make the __metadata$messageId, __metadata$messageBytes, __metadata$eventTime, and __metadata$topicName, fields available for mapping to columns in the Pinot schema.

In addition to this, if you want to use any of these columns in your table, you have to list them explicitly in your table's schema.

For example, if you want to add only the offset and key as dimension columns in your Pinot table, it can listed in the schema as follows:

  "dimensionFieldSpecs": [
    {
      "name": "__key",
      "dataType": "STRING"
    },
    {
      "name": "__metadata$messageId",
      "dataType": "STRING"
    },
    ...
  ],

Once the schema is updated, these columns are similar to any other pinot column. You can apply ingestion transforms and / or define indexes on them.

{% hint style="info" %} Remember to follow the schema evolution guidelines when updating schema of an existing table! {% endhint %}