FLUSHDB

The FLUSHDB command is used to remove all keys from the currently selected database in a DiceDB instance. This command is useful when you need to clear all the data in a specific database without affecting other databases in the same DiceDB instance.

Syntax

FLUSHDB

Parameters

The FLUSHDB command does not take any parameters.

Return Values

Condition	Return Value
Command is successful	OK
Authentication required	Error: NOAUTH Authentication required
Permission denied	Error: NOPERM this user has no permissions to run the 'flushdb' command
Read-only mode	Error: READONLY You can't write against a read-only replica

Behaviour

When the FLUSHDB command is executed, the following actions occur:

1. Immediate Deletion: All keys in the currently selected database are immediately removed.
2. Database Isolation: Only the keys in the currently selected database are affected. Other databases in the same DiceDB instance remain unchanged.
3. Persistence: If DiceDB persistence is enabled (e.g., RDB snapshots or AOF), the deletion of keys will be reflected in the next persistence operation.

Errors

The FLUSHDB command is straightforward and does not typically raise errors under normal circumstances. However, there are a few scenarios where issues might arise:

1. Authentication Issues:

   • Error Message: (error) NOAUTH Authentication required
   • Occurs when authentication is required but not provided

2. Permission Issues:

   • Error Message: (error) NOPERM this user has no permissions to run the 'flushdb' command
   • Occurs when the user lacks necessary permissions to execute the command

3. Read-Only Mode:

   • Error Message: (error) READONLY You can't write against a read-only replica
   • Occurs when attempting to execute on a read-only instance

Example Usage

Basic Usage

127.0.0.1:7379> FLUSHDB
OK

Verifying Empty Database

127.0.0.1:7379> FLUSHDB
OK
127.0.0.1:7379> DBSIZE
(integer) 0

Example with SELECT Command

While the following example shows the traditional syntax for working with multiple databases, please note that in the current version, all operations occur on a single database space:

127.0.0.1:7379> SELECT 1
OK
127.0.0.1:7379> FLUSHDB
OK
127.0.0.1:7379> DBSIZE
(integer) 0

Best Practices

• Always verify that you’re operating on the intended database before executing FLUSHDB
• Consider using backup mechanisms before executing FLUSHDB in production environments
• Use appropriate access controls to restrict FLUSHDB usage to authorized users only

Notes

• The current version of DiceDB operates on a single database space. While the SELECT command is available as a placeholder, switching databases will not affect the operation of the FLUSHDB command, and it will always clear the keys from the single available database space.

• The command is particularly powerful and should be used with caution as it results in immediate, irreversible data loss for all keys in the database.