PostgreSQL procedure for updating all sequences used as default values for table columns. Once called, it will update values of sequences to max value present in column plus 5 (why 5? So you can find out which sequences were altered). Function returns list of names of updated sequences.

set_sequence_values.py

CREATE OR REPLACE FUNCTION set_seq_vals(schema_name TEXT)
  RETURNS TEXT[]
AS $$
schemaname = schema_name if schema_name else 'public'
plpy.execute("SET SEARCH_PATH=%s,public" % schemaname)
tables = plpy.execute("SELECT tablename FROM pg_tables WHERE schemaname = '%s'" % schemaname);
altered_seqs = []
for t in tables:
    cols = plpy.execute("SELECT column_name, column_default, data_type, is_nullable FROM information_schema.columns WHERE table_name = '%s' AND data_type in ('integer', 'bigint') AND column_default IS NOT NULL" % t["tablename"])
    for c in cols:
      if not c["column_default"].lstrip().lower().startswith("nextval"):
         continue
      seqname = plpy.execute("""SELECT pg_get_serial_sequence('%s', '%s') AS "seq_name" """ % (t["tablename"], c["column_name"]))
      if seqname and seqname[0]["seq_name"] is not None:
         sname = seqname[0]["seq_name"]
         max_val = plpy.execute("""SELECT coalesce(max(%s), 1) as "mv" FROM "%s" """ % (c["column_name"], t["tablename"]))[0]
         seq_last = plpy.execute("""SELECT coalesce(last_value, 2) as "sl" FROM %s """ % (sname))[0]
         if max_val["mv"] > seq_last["sl"]:
            plpy.execute("SELECT setval('%s', %d, true)" % (sname, max_val["mv"] + 5))
            altered_seqs.append(sname)
return altered_seqs
$$ LANGUAGE plpython2u;

Language PLPython is described here: http://www.postgresql.org/docs/current/interactive/plpython.html

To make it available on your database server you need to do the following:

1. Add PLPython to your PostgreSQL installation, if not present. Ubuntu users, please do: sudo apt-get install postgresql-plpython-K.N where K.N is your PostgreSQL version (like 9.4 or 9.5)
2. In your database console (e.g. psql) run following statements: CREATE EXTENSION plpythonu; CREATE LANGUAGE plpython2u;

And you're done 👍 Good luck and have fun coding!