Inserting into Sequence/Serial Table Causes "duplicate key violates unique constraint" Error

Last edited: 1/16/2025

If you are receiving the below error for an auto-incremented table:

ERROR: duplicate key violates unique constraint

it likely means that the table's sequence has somehow become out of sync, likely because of a mass import process (or something along those lines).

Call it a "bug by design", but it seems that you have to manually reset the a primary key index after restoring from a dump file.

You can run the following commands on your instance to see if your sequence is out-of-sync:


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SELECT MAX(<sequenced_column>) FROM <table_name>;
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SELECT nextval(pg_get_serial_sequence('<public.table_name>', '<sequenced_column_name>'));

If the values are off by more than 1, you need to resynchronize your sequence.

Back up your PG database by restarting in the General Settings (just in case). When you restore your database, you will have a backup saved. Alternatively, you can also just download your properties table instead as a backup.

Then you can run this:


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SELECT SETVAL('public.<table_name>_<column_nam>_seq', (SELECT MAX(<column_name>) FROM <table_name>)+1);

That will set the sequence to the next available value that's higher than any existing primary key in the sequence.