If you get this message when trying to insert data into a PostgreSQL database:
That likely means that the primary key sequence in the table you're working with 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.
At any rate, to see if your values are out of sync, run these two commands:
ERROR: duplicate key violates unique constraint
If the first value is higher than the second value, your sequence is out of sync. Back up your PG database (just in case), then run thisL
SELECT MAX(the_primary_key) FROM the_table;
That will set the sequence to the next available value that's higher than any existing primary key in the sequence.
SELECT setval('the_primary_key_sequence', (SELECT MAX(the_primary_key) FROM the_table)+1);
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