Reading data via Query data bindings

Yandex Data Streams data bindings simplify running recurrent queries on stored data by eliminating the need to specify all operation details.

Query example for reading data via bindings:

SELECT
    JSON_VALUE(CAST(Data AS Json), "$.action") AS action
FROM bindings.`input_stream`
LIMIT 10;

Setting up a data bindingSetting up a data binding

To read Yandex Data Streams data via bindings, complete the following steps:

1. Setting up a data connection.
2. In the Type field, select Data Streams.
3. In the Connection dropdown, select the connection you created in the first step.
4. Specify the data binding name in the Name field.
5. Specify the Yandex Data Streams stream name in the Stream field.
6. Specify the data compression method in the Compression field.
7. Specify the data transfer format in the Format field.
8. Specify data columns and their data types in the Columns fields.
9. To validate the data, click Preview.
10. Click Create to create a data binding.

Data modelData model

Data is transmitted via Yandex Data Streams in binary format and is read via SQL statements.

SELECT
    <expression>
FROM
    <connection>.<stream_name>
WITH
(
    format=raw,
    SCHEMA
    (
        Data String
    )
)
WHERE <filter>;

Where:

• <connection>: Name of the Data Streams data stream connection created in the previous step.
• <stream_name>: Data Streams data stream name.

Data reading exampleData reading example

Query example for reading data from Yandex Data Streams and writing the results to Yandex Data Streams:

$data =
SELECT
    JSON_VALUE(Data, "$.host") AS host,
    JSON_VALUE(Data, "$.count") AS count,
    JSON_VALUE(Data, "$.tag") AS tag,
FROM
(
    SELECT
        CAST(Data AS Json) AS Data
    FROM bindings.`binding_name`
)
WHERE
    JSON_VALUE(Data, "$.tag") = "my_tag";

SELECT
    *
FROM
    $data
LIMIT 10;

Where: