Supported databases

DataKlin connects to PostgreSQL, MySQL and MariaDB, SQLite and Apache Cassandra. Each has its own connector in the New Connection dialog. Getting started shows the ways to open the dialog and walks through a PostgreSQL connection.

Every connection has the same Details tab: a Name, and optionally a color, an Environment tag and the Read-only checkbox. PostgreSQL and MySQL connections also have a Security tab for TLS and the authentication method. The sections below cover each connector’s General tab and its limits.

Before you connect

TLS. PostgreSQL, MySQL and MariaDB connections can use TLS, which you set on the Security tab. A new connection to a remote host uses Full verification; one to localhost isn’t encrypted. See TLS and certificates. Cassandra connections aren’t encrypted in this release, so use them only on trusted networks. SSH tunnels are planned for a later release.
Read-only is enforced. On a read-only connection, DataKlin refuses writes and schema changes before they reach the database, and asks before destructive statements on any connection. See Read-only and production safety.
Amazon Aurora and Amazon RDS connect through the PostgreSQL and MySQL connectors, with AWS IAM authentication or AWS Secrets Manager. See Amazon Aurora and RDS.
Passwords are kept as you choose next to the password field: Save, Until DataKlin quits or Ask every time. See Secret storage.

PostgreSQL

DataKlin connects to PostgreSQL 14 and later.

Choose PostgreSQL, then fill in:

Host, Port (5432 by default) and Database (postgres by default).
User and Password.
Application name, which the server shows for DataKlin’s sessions (DataKlin by default), and Connect timeout (seconds) (10 by default).
Allow md5 password authentication: tick it if your server uses md5 password authentication instead of SCRAM.

On the Security tab, choose the authentication method (Password, AWS IAM or AWS Secrets Manager) and the TLS settings.

MySQL

The MySQL / MariaDB connector connects to MySQL 8.0, 8.4 and 9.7, and to MariaDB 10.11 and 11.8.

Choose MySQL / MariaDB, then fill in:

Host and Port (3306 by default).
User and Password.
Database, the default database for names you don’t qualify. Leave it empty to choose none.
Connect timeout (seconds) (10 by default).
Allow public key retrieval (off by default). See below.

On the Security tab, choose the authentication method (Password, AWS IAM or AWS Secrets Manager) and the TLS settings.

Connections are hardened by default:

LOCAL INFILE and multi-statement queries are off. The cleartext password plugin is off too, except for AWS IAM over verified TLS (Verify CA or Full verification).
DataKlin doesn’t fetch the server’s RSA public key over an unencrypted connection unless you tick Allow public key retrieval for that connection. A caching_sha2_password or sha256_password login can need that key to send the password without TLS, but anyone who can intercept the connection could answer with their own key. Turn it on only on a trusted network.

Long queries can be cancelled, and a cancel never reaches the next statement.

SQLite

DataKlin opens SQLite database files on your computer. SQLite is built in, so there’s nothing else to install.

Choose SQLite, then fill in:

Database file: type the full path, or click Browse… to pick the file. To start a new database, click Create new… and choose where to save it; this ticks Create the file if it doesn’t exist.
Open file read-only: opens the file so that nothing, not even SQLite itself, can write to it. Writes fail with an error. It can’t be combined with Create the file if it doesn’t exist.
Busy timeout (ms) (5000 by default): how long to wait for another program’s lock on the file before giving up.
Attached databases: click Add Attached database to open up to 10 more files with this one. Give each an Alias and a File, then query its tables by the alias, such as aux.notes. The Database Explorer lists each attached database.

You can also drag a .db, .sqlite, .sqlite3 or .db3 file onto the DataKlin window: the New Connection dialog opens with the file filled in.

Limits in this release:

Cancel. Long queries can be cancelled. A statement that runs as a single step stops from your point of view, but it keeps using one CPU core in the background until that step finishes.
Large text. Very large TEXT values show as a capped “unsupported” cell.

Cassandra

DataKlin connects to Apache Cassandra 4.1 and 5.0 with a user name and password. You can browse keyspaces, tables and other objects in the Database Explorer, open their definitions (DESCRIBE), and run CQL with results fetched page by page.

Choose Apache Cassandra, then fill in:

Contact points: one or more nodes to connect to first, separated by commas. Write each as host or host:port, with IPv6 addresses in brackets, such as [::1]:9042.
Port (9042 by default), for contact points that don’t name one.
Local data centre: the data center whose nodes DataKlin talks to, such as datacenter1. If the test fails, its message lists the cluster’s data centers.
Contact points only: see below.
Default keyspace (optional), the keyspace that names you don’t qualify refer to.
User and Password. Leave them empty if the cluster doesn’t require authentication.
Connect timeout (seconds) (10 by default), Read timeout (seconds) (30 by default) and Page size (rows) (500 by default).

Limits in this release:

Plaintext only. With peer discovery on, which is the default, your credentials are sent to every node in the local data center unless you tick Contact points only, which keeps DataKlin connected to the hosts you list.
Cancel is client-side. DataKlin stops waiting for the result, but the server may finish the query.