# ksqlDB

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## Overview

ksqlDB is a powerful, SQL-like streaming engine for Apache Kafka that enables real-time data processing and transformation. Integrating ksqlDB with Condense will enable users to perform complex data transformations and aggregations on Kafka topics directly from the platform.

## **Key Features** <a href="#id-2.-key-features" id="id-2.-key-features"></a>

### **Real-Time Data Processing**

1. Execute SQL-like queries on streaming data for immediate insights.
2. Supports filtering, joins, and aggregations in real time.

### **Stream and Table Management**

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* Create, update, and delete streams and tables from Kafka topics.
* Streams for unbounded event sequences
* Tables for stateful data

### **Transient Queries**

* Run queries that process data on the fly without storing results.
* Ideal for real-time monitoring and alerting

### **User-Friendly Interface**

* Integrated directly into the Condense UI for seamless query execution.
* Visualise query results in real time.

### **Role-Based Access Control**

* **Admin/Developer**: Full access to create and manage queries.
* **Viewer**: Read-only access (no KSQL permissions)

## **How to Use KSQL** <a href="#id-3.-how-to-use-ksql" id="id-3.-how-to-use-ksql"></a>

### **Prerequisites**

* Admin or Developer role in Condense
* Access to Kafka topics with read/write permissions
* Basic knowledge of SQL syntax

### **Step 1: Access KSQL Interface**

1. Log in to Condense with your credentials
2. Navigate to **KSQL** from the main menu
3. Select **New Query** to open the editor

### **Step 2: Create a Stream**

1. For processing real-time event data, in the query editor, enter your query
2. Click **Execute** to create the stream

### **Step 3: Create a Table**

1. For stateful data, in the query editor, enter your query
2. Click **Execute** to create the table

### **Step 4: Run queries**

1. Execute transient queries for real-time analysis
2. Click **Execute** to execute and view real-time results

### **Step 5: Monitor & Troubleshoot**

Review **Error Logs**:

1. Access logs below the query editor
2. Common issues: topic permissions, schema mismatches

## Frequently Asked Questions (FAQs)

#### **Q1: What is RBAC in KSQL?**

RBAC (Role-Based Access Control) restricts access based on predefined user roles:

* **Admin**: Full create/edit/delete permissions
* **Developer**: Create/edit permissions
* **Viewer**: Read-only access (no KSQL access in initial release)

{% hint style="info" %}
This information may be updated or revised in the future
{% endhint %}

#### **Q2: Can we allow KSQL to read from some topics but not others?**

1. Grant the user "Developer" or "Admin" role in RBAC
2. Ensure ACLs allow topic creation permissions

#### **Q3: How to allow KSQL to create new streams and tables?**

Yes, ACLs can be configured at the topic level to grant or restrict access to specific topics.