具有以下查询

con= psycopg2.connect(
    dbname=database,
    user=user,
    password=pwd,
    host=host,
    port=port
)
chunk_size = 100000 #500000 rows in the DB
cursor =  con.cursor(name='custom_cursor') 
cursor.itersize = chunk_size # chunk size
cursor.execute(query)
c=0
for row in cursor:
    print(c)
    print(f"Len_row: {len(row)}")
    c+=1

据我所知，row应该由chunk_size元素组成，但是len(row)是1。由于我在DB中有500000行，所以我假设循环运行5次，但是c从0运行到行数，从0运行到4
注意：我运行的是psycopg2==2.8.6