On Thu, 2017-08-10 at 19:05 -0300, marcelo wrote: > In some table, I have a bigint column which at the app level can be > null. Call it "DocumentNumber", and of course is not the PK. > In most cases, the applications give some value to the column. > > But sometimes, the value remains null, expecting the backend or > someone > assign it a unique value. > > Could I use a sequence only when the field arrives to the backend as > null? How? Using a triger? > > Alternatively: > > How could I get the max value for the column and increment it by > one, > but with concurrency warranty? Something as a table lock? > > TIA > > > > >
Hello Marcelo, I haven't tested this but if you define the column thus:- document_number bigint default nextval('my_document_number_sequence'::regclass) then on insert, if that column is not in the values list, then the next available number from the sequence will be used. Remember, that if a rollback occurs, the sequence number is lost forever. HTH, Robert -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general