# Change Data Capture

Change Data Capture (CDC) is a technology and methodology used to capture and track changes made to data in a database, allowing you to keep track of what has been added, updated, or deleted in your database. Using an integration between Debezium, Kafka, the Semi-Structured Transformer and the Graph Writer it is possible to use this CDC data to update any graph that is based on data from the source database. In this way the source database and graph database can be kept constantly in sync. The steps of the process are as follows

* A change is made in the **SQL DB** (create, update, or delete)
* **Debezium (**connect**)** creates a payload with information of this change and writes it to **Kafka**
* The **Semi Structured Transformer** (as this payload is represented as JSON) takes the data from the Kafka topic and transformers it into **RDF** (or CSV of LPG)
* The graph data is stored as a file, the URL of which is pushed to a **Kafka** topic
* The **Graph Writer** takes the graph data and writes it to the specified Knowledge Graph

Examples of how to set up a development stack to test CDC for various database are included.

* [Debezium Setup v2.4 for MySQL](/EGeX4aTAJLlpg9Hh8kfl/change-data-capture/debezium-setup-v2.4-for-mysql.md) ->
* [Debezium Setup v2.4 for MongoDB](/EGeX4aTAJLlpg9Hh8kfl/change-data-capture/debezium-setup-v2.4-for-mongodb.md) ->
* [Debezium Setup v2.4 for Postgres](/EGeX4aTAJLlpg9Hh8kfl/change-data-capture/debezium-setup-v2.4-for-postgres.md) ->

<br>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.graph.build/EGeX4aTAJLlpg9Hh8kfl/change-data-capture.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.