How Can I Correctly Set the Current Value of a PostgreSQL Sequence?

Manually Altering PostgreSQL Sequences

In PostgreSQL, sequences are crucial for generating unique ID values for table rows. Occasionally, it becomes necessary to set the current value of a sequence to a specific number. However, some developers encounter challenges while attempting this task.

One common issue is the incorrect usage of the setval() function. The following code snippet demonstrates an incorrect approach:

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

This query results in an error because the setval() function expects two or three arguments, not just one. The corrected syntax is:

SELECT setval('payments_id_seq', 21, true);  -- next value will be 22

The second issue involves attempting to alter a sequence using the ALTER SEQUENCE command. While this command can modify sequence properties, it cannot be used to set the current value.

To successfully set the current value of a sequence to a specific number, use the following syntax:

SELECT setval('sequence_name', new_value);

Ensure that the sequence_name parameter matches the name of the sequence you intend to modify.

For example, to set the current value of the payments_id_seq sequence to 22, use the following query:

SELECT setval('payments_id_seq', 22);

Remember, the setval() function can be called both with or without the SELECT statement. However, the former approach returns the new value of the sequence, while the latter does not.

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