How to reset postgres' primary key sequence when it falls out of sync?

// Login to psql and run the following
// What is the result?
SELECT MAX(id) FROM your_table;

// Then run...
// This should be higher than the last result.
SELECT nextval('your_table_id_seq');

// If it's not higher... run this to try and fix it. (run a quick pg_dump first...)
SELECT setval('your_table_id_seq', (SELECT MAX(id) FROM your_table)+1);

CREATE OR REPLACE FUNCTION "reset_sequence" (tablename text, columnname text, sequence_name text) RETURNS "pg_catalog"."void" AS

    $body$
      DECLARE
      BEGIN

      EXECUTE 'SELECT setval( ''' || sequence_name  || ''', ' || '(SELECT MAX(' || columnname || ') FROM ' || tablename || ')' || '+1)';



      END;

    $body$  LANGUAGE 'plpgsql';


    select table_name || '_' || column_name || '_seq', reset_sequence(table_name, column_name, table_name || '_' || column_name || '_seq') from information_schema.columns where column_default like 'nextval%';

SELECT pg_catalog.setval(pg_get_serial_sequence('table_name', 'id'), (SELECT MAX(id) FROM table_name)+1);

CREATE OR REPLACE FUNCTION sequence_max_value(oid) RETURNS bigint
VOLATILE STRICT LANGUAGE plpgsql AS  $$
DECLARE
 tabrelid oid;
 colname name;
 r record;
 newmax bigint;
BEGIN
 FOR tabrelid, colname IN SELECT attrelid, attname
               FROM pg_attribute
              WHERE (attrelid, attnum) IN (
                      SELECT adrelid::regclass,adnum
                        FROM pg_attrdef
                       WHERE oid IN (SELECT objid
                                       FROM pg_depend
                                      WHERE refobjid = $1
                                            AND classid = 'pg_attrdef'::regclass
                                    )
          ) LOOP
      FOR r IN EXECUTE 'SELECT max(' || quote_ident(colname) || ') FROM ' || tabrelid::regclass LOOP
          IF newmax IS NULL OR r.max > newmax THEN
              newmax := r.max;
          END IF;
      END LOOP;
  END LOOP;
  RETURN newmax;
END; $$ ;

select relname, setval(oid, sequence_max_value(oid))
   from pg_class
  where relkind = 'S';

select relname, setval(pg_class.oid, sequence_max_value(pg_class.oid))
  from pg_class, pg_namespace
 where pg_class.relnamespace = pg_namespace.oid and
       nspname = 'public' and
       relkind = 'S';

alvherre=# d baz
                     Tabla «public.baz»
 Columna |  Tipo   |                 Modificadores
---------+---------+------------------------------------------------
 a       | integer | default nextval(('foo_a_seq'::text)::regclass)

alvherre=# alter table baz alter a set default nextval('foo_a_seq');
ALTER TABLE

alvherre=# d baz
                     Tabla «public.baz»
 Columna |  Tipo   |             Modificadores
---------+---------+----------------------------------------
 a       | integer | default nextval('foo_a_seq'::regclass)

CREATE OR REPLACE FUNCTION "reset_sequence" (tablename text) RETURNS "pg_catalog"."void" AS
$body$
  DECLARE
  BEGIN
  EXECUTE 'SELECT setval( '''
  || tablename
  || '_id_seq'', '
  || '(SELECT id + 1 FROM "'
  || tablename
  || '" ORDER BY id DESC LIMIT 1), false)';
  END;
$body$  LANGUAGE 'plpgsql';

select sequence_name, reset_sequence(split_part(sequence_name, '_id_seq',1)) from information_schema.sequences
        where sequence_schema='public';

CREATE OR REPLACE FUNCTION  rebuilt_sequence() RETURNS integer as ''
DECLARE
sequencedefs RECORD;
c integer ;
BEGIN
FOR sequencedefs IN Select
constraint_column_usage.table_name as tablename,
constraint_column_usage.table_name as tablename,
constraint_column_usage.column_name as columnname,
replace(replace(columns.column_default,'''::regclass)',''),'nextval(''','') as sequencename
from information_schema.constraint_column_usage,
information_schema.columns
where constraint_column_usage.table_schema ='public' AND
columns.table_schema = 'public' AND
columns.table_name=constraint_column_usage.table_name AND
constraint_column_usage.column_name = columns.column_name AND
columns.column_default is not null
LOOP
   EXECUTE 'select max('||sequencedefs.columnname||') from ' || sequencedefs.tablename INTO c;

IF c is not null THEN
c = c+ 1;
EXECUTE 'alter sequence ' || sequencedefs.sequencename ||' restart with ' ||c;
END LOOP;
RETURN 1;
END;
$$ LANGUAGE plpgsql;

select sequence_name, --PG_CLASS.relname, PG_ATTRIBUTE.attname
       reset_sequence(split_part(sequence_name, '_id_seq',1))
from PG_CLASS
join PG_ATTRIBUTE on PG_ATTRIBUTE.attrelid = PG_CLASS.oid
join information_schema.sequences
     on information_schema.sequences.sequence_name = PG_CLASS.relname || '_' || PG_ATTRIBUTE.attname
where sequence_schema='public';

drop function IF EXISTS rebuilt_sequences() RESTRICT;
CREATE OR REPLACE FUNCTION  rebuilt_sequences() RETURNS integer as
$body$
  DECLARE sequencedefs RECORD; c integer ;
  BEGIN
    FOR sequencedefs IN Select
      constraint_column_usage.table_name as tablename,
      constraint_column_usage.table_name as tablename,
      constraint_column_usage.column_name as columnname,
      replace(replace(columns.column_default,'''::regclass)',''),'nextval(''','') as sequencename
      from information_schema.constraint_column_usage, information_schema.columns
      where constraint_column_usage.table_schema ='public' AND
      columns.table_schema = 'public' AND columns.table_name=constraint_column_usage.table_name
      AND constraint_column_usage.column_name = columns.column_name
      AND columns.column_default is not null
   LOOP
      EXECUTE 'select max('||sequencedefs.columnname||') from ' || sequencedefs.tablename INTO c;
      IF c is null THEN c = 0; END IF;
      IF c is not null THEN c = c+ 1; END IF;
      EXECUTE 'alter sequence ' || sequencedefs.sequencename ||' restart  with ' || c;
   END LOOP;

   RETURN 1; END;
$body$ LANGUAGE plpgsql;

select rebuilt_sequences();

--drop function IF EXISTS reset_sequence (text,text) RESTRICT;
CREATE OR REPLACE FUNCTION "reset_sequence" (tablename text,columnname text) RETURNS bigint --"pg_catalog"."void"
AS
$body$
  DECLARE seqname character varying;
          c integer;
  BEGIN
    select tablename || '_' || columnname || '_seq' into seqname;
    EXECUTE 'SELECT max("' || columnname || '") FROM "' || tablename || '"' into c;
    if c is null then c = 0; end if;
    c = c+1; --because of substitution of setval with "alter sequence"
    --EXECUTE 'SELECT setval( "' || seqname || '", ' || cast(c as character varying) || ', false)'; DOES NOT WORK!!!
    EXECUTE 'alter sequence ' || seqname ||' restart with ' || cast(c as character varying);
    RETURN nextval(seqname)-1;
  END;
$body$ LANGUAGE 'plpgsql';

select sequence_name, PG_CLASS.relname, PG_ATTRIBUTE.attname,
       reset_sequence(PG_CLASS.relname,PG_ATTRIBUTE.attname)
from PG_CLASS
join PG_ATTRIBUTE on PG_ATTRIBUTE.attrelid = PG_CLASS.oid
join information_schema.sequences
     on information_schema.sequences.sequence_name = PG_CLASS.relname || '_' || PG_ATTRIBUTE.attname || '_seq'
where sequence_schema='public';

BEGIN;
CREATE OR REPLACE FUNCTION reset_sequence(_table_schema text, _tablename text, _columnname text, _sequence_name text)
RETURNS pg_catalog.void AS
$BODY$
DECLARE
BEGIN
 PERFORM 1
 FROM information_schema.sequences
 WHERE
  sequence_schema = _table_schema AND
  sequence_name = _sequence_name;
 IF FOUND THEN
  EXECUTE 'SELECT setval( ''' || _table_schema || '.' || _sequence_name  || ''', ' || '(SELECT MAX(' || _columnname || ') FROM ' || _table_schema || '.' || _tablename || ')' || '+1)';
 ELSE
  RAISE WARNING 'SEQUENCE NOT UPDATED ON %.%', _tablename, _columnname;
 END IF;
END;
$BODY$
 LANGUAGE 'plpgsql';

SELECT reset_sequence(table_schema, table_name, column_name, table_name || '_' || column_name || '_seq')
FROM information_schema.columns
WHERE column_default LIKE 'nextval%';

DROP FUNCTION reset_sequence(_table_schema text, _tablename text, _columnname text, _sequence_name text) ;
COMMIT;