How Do I Manually Reset a PostgreSQL Sequence to a Specific Value?

Manually Altering Sequence Values in Postgres

When working with sequences in PostgreSQL, you may encounter scenarios where resetting a sequence's current value to a specific number is necessary. However, attempts to manipulate sequences using familiar methods may result in errors.

Setting a Sequence to a Specific Value

To set a sequence to a particular value, the correct syntax is:

SELECT setval('sequence_name', new_value, is_called);

Where:

• 'sequence_name' is the name of the sequence you want to modify.
• 'new_value' is the desired value for the next sequence number.
• 'is_called' is a boolean value indicating whether the sequence will be called after setting the value (true: called, false: not called).

Example:

To set the 'payments_id_seq' sequence to the value 21, use the following command:

SELECT setval('payments_id_seq', 21, true);

Additional Considerations:

• Ensure that the sequence exists in the database before attempting to manipulate it.
• The 'new_value' must be greater than or equal to the current value of the sequence.
• If 'is_called' is set to true, the sequence will be called, incrementing the sequence value by one when it is used.

Alternative Syntax:

Alternatively, you can use the ALTER SEQUENCE command to modify sequence values:

ALTER SEQUENCE sequence_name RESTART WITH new_value;

However, it's important to note that ALTER SEQUENCE does not allow specifying whether the sequence will be called after the change.

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