How to Manually Alter PostgreSQL Sequences and Troubleshoot Common Errors?

Altering Sequences in PostgreSQL Manually

When attempting to set a sequence to a specific value, users may encounter errors. This article addresses common issues and provides solutions for manually altering sequences in PostgreSQL.

Error: Function setval(unknown) does not exist

This error occurs when the parentheses in the setval statement are incorrectly placed. The correct syntax is:

SELECT setval('sequence_name', value [, is_called]);

Where:

• 'sequence_name' is the name of the sequence to be altered.
• 'value' is the new starting value for the sequence.
• 'is_called' is an optional boolean parameter that specifies whether the sequence is currently being used.

Error: ALTER SEQUENCE not working

The ALTER SEQUENCE statement is used to modify the properties of a sequence, including the last value. However, this statement should be used with caution, as it can cause conflicts if the sequence is being used concurrently.

To avoid errors, it is recommended to use the setval function instead of ALTER SEQUENCE. The setval function sets the next value of the sequence to the specified value and ensures that the sequence is not being used by another session.

Example

To set the next value of the 'payments_id_seq' sequence to 22, execute the following statement:

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

This statement will set the next value of the sequence to 22, and the following value obtained from the sequence will be 23.

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