import psycopg2
import sys
from os import listdir
from os.path import isfile, join
import csv
import re
import io

try:
    con = db_connect("dbname = '[redacted]' user = '[redacted]' password = '[redacted]' host = '[redacted]'")
except:
    print("Can't connect to database.")
    sys.exit(1)
cur = con.cursor()

upload_file = io.StringIO()

file_list = [f for f in listdir(mypath) if isfile(join(mypath, f))]
for file in file_list:
    id_match = re.search(r'.*-(d+).csv', file)
    if id_match:
        id = id_match.group(1)
        file_name = format(id_match.group())
        with open(mypath+file_name) as fh:
            id_reader = csv.reader(fh)
            next(id_reader, None)   # Skip the header row
            for row in id_reader:
                [stuff goes here to get desired values from file]
                if upload_file.getvalue() != '': upload_file.write('n')
            upload_file.write('{0}t{1}t{2}'.format(id, [val1], [val2]))

print(upload_file.getvalue())   # prints output that looks like I expect it to
          # with thousands of rows that seem to have the right values in the right fields

cur.copy_from(upload_file, '[my_table]', sep='t', columns=('id', 'col_1', 'col_2'))
con.commit()

if con:
    con.close()