1.- Update all the sequences in a schema (ids, keys)

CREATE OR REPLACE FUNCTION setval_max
(
    schema_name name,
    table_name name DEFAULT NULL::name,
    raise_notice boolean DEFAULT false
)
RETURNS void AS
$BODY$

-- Sets all the sequences in the schema "schema_name" to the max(id) of every table (or a specific table, if name is supplied)
-- Examples:
--  SELECT setval_max('public');
--  SELECT setval_max('public','mytable');
--  SELECT setval_max('public',null,true);
--  SELECT setval_max('public','mytable',true);

DECLARE
    row_data RECORD;
    sql_code TEXT;

BEGIN
    IF ((SELECT COUNT(*) FROM pg_namespace WHERE nspname = schema_name) = 0) THEN
        RAISE EXCEPTION 'The schema "%" does not exist', schema_name;
    END IF;

    FOR sql_code IN
        SELECT 'SELECT SETVAL(' ||quote_literal(N.nspname || '.' || S.relname)|| ', MAX(' ||quote_ident(C.attname)|| ') ) FROM ' || quote_ident(N.nspname) || '.' || quote_ident(T.relname)|| ';' AS sql_code
            FROM pg_class AS S
            INNER JOIN pg_depend AS D ON S.oid = D.objid
            INNER JOIN pg_class AS T ON D.refobjid = T.oid
            INNER JOIN pg_attribute AS C ON D.refobjid = C.attrelid AND D.refobjsubid = C.attnum
            INNER JOIN pg_namespace N ON N.oid = S.relnamespace
            WHERE S.relkind = 'S' AND N.nspname = schema_name AND (table_name IS NULL OR T.relname = table_name)
            ORDER BY S.relname
    LOOP
        IF (raise_notice) THEN
            RAISE NOTICE 'sql_code: %', sql_code;
        END IF;
        EXECUTE sql_code;
    END LOOP;
END;
$BODY$
LANGUAGE plpgsql VOLATILE;

and calling it by

SELECT setval_max('public');

2.- Delete all tables in a schema

After selecting a schema…

DO $$ DECLARE
    r RECORD;
BEGIN
    FOR r IN (SELECT tablename FROM pg_tables WHERE schemaname = current_schema()) LOOP
        EXECUTE 'DROP TABLE IF EXISTS ' || quote_ident(r.tablename) || ' CASCADE';
    END LOOP;
END $$;

Sources: https://stackoverflow.com/questions/3327312/how-can-i-drop-all-the-tables-in-a-postgresql-database

http://dbadailystuff.com/2013/12/03/setval-for-all-sequences-in-a-schema