Sink data from RisingWave to OpenSearch

This guide describes how to sink data from RisingWave to OpenSearch using the OpenSearch sink connector in RisingWave.

OpenSearch is the flexible, scalable, open-source way to build solutions for data-intensive applications. For more information about OpenSearch, see OpenSearch official website.

PREMIUM FEATURE

This is a premium feature. For a comprehensive overview of all premium features and their usage, please see RisingWave premium features.

Prerequisites

• Ensure the OpenSearch cluster is accessible from RisingWave.
• If you are running RisingWave locally from binaries, make sure that you have JDK 11 or later versions installed in your environment.

Create an OpenSearch sink

Use the following syntax to create an OpenSearch sink. Once a sink is created, any insert or update to the sink will be streamed to the specified OpenSearch endpoint.

CREATE SINK sink_name
[ FROM sink_from | AS select_query ]
WITH (
  connector = 'opensearch',
  primary_key = '<primary key of the sink_from object>',
  { index = '<your opensearch index>' | index_column = '<your index column>' },
  url = 'http://<opensearch hostname>:<opensearch port>',
  username = '<your opensearch username>',
  password = '<your password>',
  delimiter='<delimiter>'
);

Parameters

Parameter	Description
sink_name	Name of the sink to be created.
sink_from	A clause that specifies the direct source from which data will be output. sink_from can be a materialized view or a table. Either this clause or a SELECT query must be specified.
AS select_query	A SELECT query that specifies the data to be output to the sink. Either this query or a FROM clause must be specified. See SELECT for the syntax and examples of the SELECT command.
primary_key	Optional. The primary keys of the sink. If the primary key has multiple columns, set a delimiter in the delimiter parameter below to join them.
index	Required if index_column is not set. Name of the OpenSearch index that you want to write data to.
index_column	This parameter enables you to create a sink that writes to multiple indexes dynamically. The sink decides which index to write to based on a column. It is mutually exclusive with the parameter index. Only one of them can and must be set. When index is set, the write index of OpenSearch is index. When index_column is set, the index of OpenSearch is the value of this column, which must be the string type. Since OpenSearch sink defaults to the first column as the key, it is not recommended to place this column as the first column.
routing_column	Optional. Allows setting a column as a routing key, so that it can direct writes to specific shards based on its value.
retry_on_conflict	Optional. Number of retry attempts after an optimistic locking conflict occurs.
batch_size_kb	Optional. Maximum size (in kilobytes) for each request batch sent to OpenSearch. If the data exceeds this size，the current batch will be sent.
batch_num_messages	Optional. Maximum number of messages per request batch sent to OpenSearch. If the number of messages exceeds this size，the current batch will be sent.
concurrent_requests	Optional. Maximum number of concurrent threads for sending requests.
url	Required. URL of the OpenSearch REST API endpoint.
username	Optional. opensearch user name for accessing the OpenSearch endpoint. It must be used with password.
password	Optional. Password for accessing the OpenSearch endpoint. It must be used with username.
delimiter	Optional. Delimiter for OpenSearch ID when the sink’s primary key has multiple columns.

Notes about primary keys and OpenSearch IDs

The OpenSearch sink defaults to the upsert sink type. It does not support the append-only sink type.

The OpenSearch sink detects column-level changes during upserts and sends only the modified columns, helping reduce the load on OpenSearch.

To customize your OpenSearch ID, specify it via the primary_key parameter. RisingWave will combine multiple primary key values into a single string with the delimiter set, and use it as the OpenSearch ID.

If you don’t want to customize your OpenSearch ID, RisingWave will use the first column in the sink definition as the OpenSearch ID.

Data type mapping

OpenSearch uses a mechanism called dynamic field mapping to dynamically create fields and determine their types automatically. It treats all integer types as long and all floating-point types as float. To ensure data types in RisingWave are mapped to the data types in OpenSearch correctly, we recommend that you specify the mapping via index templates.

RisingWave Data Type	OpenSearch Field Type
boolean	boolean
smallint	long
integer	long
bigint	long
numeric	text
real	float
double precision	float
character varying	text
bytea	text
date	date
time without time zone	text
timestamp without time zone	text
timestamp with time zone	text
interval	text
struct	object
array	array
JSONB	object (RisingWave’s OpenSearch sink will send JSONB as a JSON string, and OpenSearch will convert it into an object)

OpenSearch doesn’t require users to explicitly CREATE TABLE. Instead, it infers the schema on-the-fly based on the first record ingested. For example, if a record contains a jsonb {v1: 100}, v1 will be inferred as a long type. However, if the next record is {v1: "abc"}, the ingestion will fail because "abc" is inferred as a string and the two types are incompatible.

This behavior may lead to missing records. For monitoring, see Grafana, where there is a panel for all sink write errors.