Postgres and Open Source Experts

In PostgreSQL, the ALTER TABLE statement is executed with the “ADD GENERATED AS IDENTITY” option to add an IDENTITY column to a pre-existing table.

In PostgreSQL, the “lastval of the sequence is not yet defined” error occurs when the LASTVAL() function is invoked/called prior to the NEXTVAL() function.

The “column can only be updated to DEFAULT” error arises when a user tries to update the value of an IDENTITY column that is created using the "GENERATED ALWAYS" option.

To drop or delete an IDENTITY column from a table, execute the ALTER TABLE statement with the DROP IDENTITY option.

The "step size can't equal zero" error in PostgreSQL occurs when a user uses a wrong step size of 0 while generating a series using the generate_series() function.

In PostgreSQL, altering a regular column to an IDENTITY column requires the targeted column to be defined as NOT NULL.

The “can't insert a non-default value into column id” error arises when a user tries to insert the value to an IDENTITY column that is created using the "GENERATED ALWAYS" option.

To alter the “max_connections” parameter in Postgres, the “ALTER SYSTEM SET max_connections = num_of_connections;” command is used.

In PostgreSQL, “LASTVAL()” is a built-in function that retrieves the most recently generated sequence value of the current session.

In PostgreSQL, the ALTER TABLE statement is used with ADD IDENTITY or DROP IDENTITY to add or remove an IDENTITY column to a Postgres table.