The Kafka Connect OmniSci sink connector allows you to export data from Apache Kafka® topics to OmniSci.
The connector polls data from Kafka to write to OmniSci based on the topics subscription.
Install the OmniSci Connector
You can install this connector by using the instructions or you can
manually download the ZIP file.
Install the connector using Confluent Hub
- Prerequisite
- Confluent Hub Client must be installed. This is installed by default with Confluent Enterprise.
Navigate to your Confluent Platform installation directory and run the following command to install the latest (latest
) connector version. The connector must be installed on every machine where Connect will run.
confluent-hub install confluentinc/kafka-connect-omnisci:latest
You can install a specific version by replacing latest
with a version number. For example:
confluent-hub install confluentinc/kafka-connect-omnisci:1.0.2
Quick Start
In this quickstart, you copy Avro data from a single topic
to a local OmniSci database running on Docker.
This example assumes you are running Kafka and Schema Registry locally on the default ports.
It also assumes your have Docker installed and running.
First, bring up OmniSci database by running the following Docker command:
docker run -d -p 6274:6274 omnisci/core-os-cpu:v4.7.0
This brings up the CPU based community version of OmniSci, and maps it to port 6274 on localhost.
By default, the user name is admin
and the password is HyperInteractive
.
The default database is omnisci
.
Start the Confluent Platform using the Confluent CLI command below.
Tip
The command syntax for the Confluent CLI development commands changed in 5.3.0.
These commands have been moved to confluent local
. For example, the syntax for confluent start
is now
confluent local services start
. For more information, see confluent local.
confluent local services start
Property-based example
Next, create a configuration file for the connector. This configuration is used
typically along with standalone workers. This file is
included with the connector in ./etc/kafka-connect-omnisci/omnisci-sink-connector.properties
and contains the following settings:
name=OmnisciSinkConnector
connector.class=io.confluent.connect.omnisci.OmnisciSinkConnector
tasks.max=1
topics=orders
connection.database=omnisci
connection.port=6274
connection.host=localhost
connection.user=admin
connection.password=HyperInteractive
confluent.topic.bootstrap.servers=localhost:9092
confluent.topic.replication.factor=1
auto.create=true
The first few settings are common settings you specify for all connectors, except for
topics which are specific to sink connectors like this one.
The connection.url
, connection.user
and connection.password
specify the connection URL, username, and password of the local OmniSci
database. Since auto.create
is enabled, the connector creates the table if it is not present.
Run the connector with this configuration.
confluent load OmnisciSinkConnector -d etc/kafka-connect-omnisci/omnisci-sink-connector.properties
REST-based example
This configuration is used typically along with distributed workers.
Write the following json to omnisci-sink-connector.json
, configure all of the required values,
and use the command below to post the configuration to one the distributed connect worker(s).
Check here for more information about the
Kafka Connect REST API
{
"name" : "OmnisciSinkConnector",
"config" : {
"connector.class" : "io.confluent.connect.omnisci.OmnisciSinkConnector",
"tasks.max" : "1",
"topics": "orders",
"connection.database": "omnisci",
"connection.port": "6274",
"connection.host": "localhost",
"connection.user": "admin",
"connection.password": "HyperInteractive",
"confluent.topic.bootstrap.servers": "localhost:9092",
"confluent.topic.replication.factor": "1",
"auto.create": "true"
}
}
Use curl to post the configuration to one of the Kafka Connect workers. Change http://localhost:8083/ the endpoint of
one of your Kafka Connect worker(s).
Run the connector with this configuration.
curl -X POST -d @omnisci-sink-connector.json http://localhost:8083/connectors -H "Content-Type: application/json"
Next, create a record in the orders
topic
bin/kafka-avro-console-producer \
--broker-list localhost:9092 --topic orders \
--property value.schema='{"type":"record","name":"myrecord","fields":[{"name":"id","type":"int"},{"name":"product", "type": "string"}, {"name":"quantity", "type": "int"}, {"name":"price",
"type": "float"}]}'
The console producer is waiting for input. Copy and paste the following record into the terminal:
{"id": 999, "product": "foo", "quantity": 100, "price": 50}
To verify the data in OmniSci, log in to the Docker container using the following command:
docker exec -it <containerid> bash
Tip
To find the container id, you can run the following command
Once you are inside the Docker container, launch omnisql:
When prompted for a password, enter HyperInteractive
.
Finally, run the following SQL query to verify the records:
omnisql> select * from orders;
foo|50.0|100|999
Data mapping
The sink connector requires knowledge of schemas, so you should use a suitable converter
like the Avro converter that comes with Schema Registry or the JSON converter with schemas enabled.
Kafka record keys (if present) can be primitive types or a Connect struct.
The record value must be a Connect struct.
Fields being selected from Connect structs must be primitive types.
If the data in the topic is not of a compatible format,
implementing a custom Converter
may be necessary.
Auto-creation and Auto-evolution
Tip
Make sure the OmniSci user has the appropriate permissions for DDL.
If auto.create
is enabled, the connector can CREATE
the destination table if it is found to be missing.
The creation takes place online with records being consumed from the topic, since the connector uses the
record schema as a basis for the table definition.
Note that OmniSci does not support default values for columns. If your schema has fields
with default values, they are added but the default value is ignored.
If auto.evolve
is enabled, the connector can perform limited auto-evolution by issuing
ALTER
on the destination table when it encounters a record for which
a column is found to be missing.
Since data-type changes and removal of columns can be dangerous, the connector does not attempt to perform such evolutions on the table.
Addition of primary key constraints is also not attempted.
Important
For backward-compatible table schema evolution, new fields in record schemas must be optional.
Mandatory fields, with or without a default value, are NOT supported.
If you need to delete a field, the table schema should be manually altered to drop the corresponding column.
Marking the column nullable does not work. You must drop the corresponding column.