python - How can one optimize this MySQL count algorithm? -


i have 2 tables; 1 users , other records user actions. want count number of actions per user , record in users table. there ~100k user , following code takes 6 hours! there must better way!

def calculate_invites():

sql_db.execute("select id, uid users")  row in sql_db:     id = row['id']     uid = row['uid']      sql1 = "select count(1) actions uid = %s"     sql_db.execute(sql1, uid)     count_actions = sql_db.fetchone()["count(1)"]      sql = "update users set count_actions=%s uid=%s"     sql_db.execute(sql, (count_actions, uid))

you can 1 statement:

update users     set count_actons = (select count(*) actions a.uid = users.uid)

no loop. no multiple queries. in sql can in sql. looping on rows want in database rather in application.


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