Add DynamoDB connector support (define_dynamodb_connection + dynamodb datasource block)

[gnzjgo]

Summary

The Tinybird DynamoDB connector is generally available through the Tinybird CLI (tb connection create dynamodb, TYPE dynamodb in .connection files, IMPORT_TABLE_ARN / IMPORT_EXPORT_BUCKET in .datasource files), but the Python SDK currently only exposes helpers for Kafka, S3, and GCS.

This forces SDK users to keep a mixed project (Python definitions + raw .connection / .datasource files) just for DynamoDB.

Docs page: https://www.tinybird.co/docs/forward/ingest-data/connectors/dynamodb

Proposal

Add a define_dynamodb_connection helper and a dynamodb block on define_datasource, mirroring the Kafka / S3 / GCS shape.

Connection

from tinybird_sdk import define_dynamodb_connection, secret

my_ddb = define_dynamodb_connection("my_ddb", {
    "arn": secret("dynamodb_role_arn_my_ddb"),  # DYNAMODB_ARN
    "region": "us-east-1",                       # DYNAMODB_REGION
})

Datasource

from tinybird_sdk import define_datasource, engine, t
from .connections import my_ddb

orders = define_datasource("orders", {
    "schema": {
        "pk": t.string(),
        "sk": t.string(),
        "_record": t.string(),
        "_old_record": t.string().nullable(),
        "_timestamp": t.date_time64(3),
        "_event_name": t.string().low_cardinality(),
        "_is_deleted": t.uint8(),
    },
    "engine": engine.replacing_merge_tree({
        "sorting_key": ["pk", "sk"],
        "ver": "_timestamp",
        "is_deleted": "_is_deleted",
    }),
    "dynamodb": {
        "connection": my_ddb,
        "table_arn": "arn:aws:dynamodb:us-east-1:123456789012:table/orders",  # IMPORT_TABLE_ARN
        "export_bucket": "my-orders-exports",                                  # IMPORT_EXPORT_BUCKET
    },
})

Notes:

• The DynamoDB datasource must use ReplacingMergeTree; consider validating this in the SDK.
• The columns _record, _old_record, _timestamp, _event_name, _is_deleted are mandatory system columns. Consider exposing them as a helper / preset so users don't have to redeclare them every time.
• Once engine.replacing_merge_tree and the dynamodb block exist, the docs at https://www.tinybird.co/docs/forward/ingest-data/connectors/dynamodb can add Python SDK tabs alongside the Tinybird CLI ones.

Mirror of the matching request on the TypeScript SDK: tinybirdco/tinybird-sdk-typescript#164

Why

Today docs need an explicit callout that the DynamoDB connector is CLI-datafile-only, which breaks the "define everything in Python" workflow the SDK is built around.