# ClickHouse

Click House is a column-oriented Database Management System for Online Analytics Processing of Queries (OAPL). 

<figure><img src="https://content.gitbook.com/content/hTnkoJQml0pok9awFDhx/blobs/cT3QYQlxPHclaih3pbHh/Clickhouse.webp" alt=""><figcaption></figcaption></figure>

> The connectivity to Click House is via JDBC driver, which is included in the platform.

The drivers used by the connector are given below:

> **Driver / API:** ClickHouse JDBC driver
>
> **Version:** 1.0 (latest version is 0.31)
>
> **Details:** Is JDBC 0.2.4
>
> <https://mvnrepository.com/artifact/ru.yandex.clickhouse/clickhouse-jdbc/0.2.4>

## Connector Capabilities

The connector capabilities are shown below:

### **Crawling**

Supported objects for Crawling are:

| Supported Object                                                                                        | Supported Data type                                                                      |
| ------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------- |
| Tables, Table Columns, Views, Stored Procedures, Functions, Roles, Users, Permissions, Usage Statistics | LONGBLOB, LONGTEXT, TINYTEXT, TEXT, VARCHAR, MEDIUMBLOB, BLOB, TINYBLOB, CHAR, MEDIUMTEX |

&#x20;Please see this article [Crawling Data](https://support.ovaledge.com/step-by-step-guide-to-setup-ovaledge-crawlers) for more details on crawling.&#x20;

### **Profiling**

| Feature          | Support                                       | Remarks                                           |
| ---------------- | --------------------------------------------- | ------------------------------------------------- |
| Table Profiling  | Row count, Columns count, View sample data    |                                                   |
| View Profiling   | Row count, Columns count, View sample data    | View is treated as a table for profiling purposes |
| Column Profiling | Min, Max, Null count, distinct, top 50 values |                                                   |
| Full Profiling   | Supported                                     |                                                   |
| Sample Profiling | Supported                                     |                                                   |

Please see [Profiling Data](https://support.ovaledge.com/step-by-step-guide-to-setup-ovaledge-profiling) for more details on profiling.

### **Lineage Building**

| Lineage Entities | Details                                         |
| ---------------- | ----------------------------------------------- |
| Table lineage    | Supported                                       |
| Column lineage   | Supported                                       |
| Lineage Sources  | Stored procedures, functions, views, query logs |

### **Querying**

| Operation              | Details                                                    |
| ---------------------- | ---------------------------------------------------------- |
| Select                 | Supported                                                  |
| Insert                 | Supported provided its service account have the permission |
| Update                 | Supported provided its service account have the permission |
| Delete                 | Supported provided its service account have the permission |
| Joins within database  | Supported                                                  |
| Joins outside database | Not supported                                              |
| Aggregations           | Supported                                                  |
| Group By               | Supported                                                  |
| Order By               | Supported                                                  |

> By default the service account provided for the connector will be used for any query operations. If the service account has write privileges, then Insert / Update / Delete queries can be executed.

## **Pre-requisites**

To use the connector, the following need to be available:

* Connection details as specified in the following section should be available.
* A service account with read privileges.
* JDBC driver is provided by default.

### **Connection Details**

The following connection settings should be added for connecting to a ClickHouse:

* **Database Type:** Click House
* **License Type:** Standard
* **Connection Name:** Select a Connection name for the ClickHouse database. The name that you specify is a reference name to easily identify your ClickHouse database connection in OvalEdge. Example: ClickHouse Connection&#x20;
* **Hostname / IP Address:** Database instance URL (on-premises/cloud-based)\
  Example: ip
* **Port number:** 8123 (Default)
* **Sid / Database:** Name of the database to connect to.
* **Username:** Default (based upon your connection)
* **Password:** 0valEdge! (based upon your connection)
* **Driver Name:** JDBC driver name for ClickHouse. Need to add in pom.xml. Need not to download external drivers.\
  Example: <https://mvnrepository.com/artifact/ru.yandex.clickhouse/clickhouse-jdbc/0.2.4>
* **Connection String:** ClickHouse has a connection string. Set the Connection string toggle button to automatic, to get the details automatically from the credentials provided. Alternatively, you can manually enter the string.\
  **Format:** jdbc:clickhouse://3.84.239.121:8123/test

> Once connectivity is established, additional configurations for [Crawling](https://support.ovaledge.com/understanding-crawler-settings) and [Profiling](https://support.ovaledge.com/understanding-profiling-settings) can be specified.

| Property                   | Details                                                                            |
| -------------------------- | ---------------------------------------------------------------------------------- |
| **Crawler configurations** |                                                                                    |
| Tables, Views, Columns     | By default it is selected true                                                     |
| Crawler rules              | Default include tables regex has  regex = (.\*) , which can crawl all the tables   |
| **Profile Settings**       |                                                                                    |
| Tables and columns         | By default it is selected true                                                     |
| Views and columns          | By default it is selected true                                                     |
| Profile Rules              | Default include tables regex has  regex = (.\*) , which can profile all the tables |
| Query Log Setting          |                                                                                    |

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