如何优化postgresql过程

我有6100万封带有状态的非唯一电子邮件。 此电子邮件需要按状态使用逻辑进行重复数据消除

我编写了存储过程，但这个过程运行时间很长

如何优化此过程的执行时间

CREATE OR REPLACE FUNCTION public.load_oxy_emails() RETURNS boolean AS $$

DECLARE
        row record;
        rec record;
        new_id int;
BEGIN
        FOR row IN SELECT * FROM oxy_email ORDER BY id LOOP
                SELECT * INTO rec FROM oxy_emails_clean WHERE email = row.email;
                IF rec IS NOT NULL THEN
                        IF row.status = 3 THEN
                                UPDATE oxy_emails_clean SET status = 3 WHERE id = rec.id;
                        END IF;
                ELSE
                        INSERT INTO oxy_emails_clean(id, email, status) VALUES(nextval('oxy_emails_clean_id_seq'), row.email, row.status);
                        SELECT currval('oxy_emails_clean_id_seq') INTO new_id;
                        INSERT INTO oxy_emails_clean_websites_relation(oxy_emails_clean_id, website_id) VALUES(new_id, row.website_id);
                END IF;
        END LOOP;
        RETURN true;
END;
$$
LANGUAGE 'plpgsql';

如何优化此过程的执行时间

CREATE OR REPLACE FUNCTION public.load_oxy_emails() RETURNS boolean AS $$

DECLARE
        row record;
        rec record;
        new_id int;
BEGIN
        FOR row IN SELECT * FROM oxy_email ORDER BY id LOOP
                SELECT * INTO rec FROM oxy_emails_clean WHERE email = row.email;
                IF rec IS NOT NULL THEN
                        IF row.status = 3 THEN
                                UPDATE oxy_emails_clean SET status = 3 WHERE id = rec.id;
                        END IF;
                ELSE
                        INSERT INTO oxy_emails_clean(id, email, status) VALUES(nextval('oxy_emails_clean_id_seq'), row.email, row.status);
                        SELECT currval('oxy_emails_clean_id_seq') INTO new_id;
                        INSERT INTO oxy_emails_clean_websites_relation(oxy_emails_clean_id, website_id) VALUES(new_id, row.website_id);
                END IF;
        END LOOP;
        RETURN true;
END;
$$
LANGUAGE 'plpgsql';

不要做循环

执行逐行处理（也称为逐行慢处理）几乎总是比执行批量更改（其中一条语句一次性处理大量行）慢得多

使用一条语句即可轻松更改状态：

update oxy_emails_clean oec
    SET status = 3
from oxy_email oe
where oe.id = oec.id
  and oe.status = 3;

行的复制可以使用以下链接完成：

如何优化此过程的执行时间

CREATE OR REPLACE FUNCTION public.load_oxy_emails() RETURNS boolean AS $$

DECLARE
        row record;
        rec record;
        new_id int;
BEGIN
        FOR row IN SELECT * FROM oxy_email ORDER BY id LOOP
                SELECT * INTO rec FROM oxy_emails_clean WHERE email = row.email;
                IF rec IS NOT NULL THEN
                        IF row.status = 3 THEN
                                UPDATE oxy_emails_clean SET status = 3 WHERE id = rec.id;
                        END IF;
                ELSE
                        INSERT INTO oxy_emails_clean(id, email, status) VALUES(nextval('oxy_emails_clean_id_seq'), row.email, row.status);
                        SELECT currval('oxy_emails_clean_id_seq') INTO new_id;
                        INSERT INTO oxy_emails_clean_websites_relation(oxy_emails_clean_id, website_id) VALUES(new_id, row.website_id);
                END IF;
        END LOOP;
        RETURN true;
END;
$$
LANGUAGE 'plpgsql';

不要做循环

执行逐行处理（也称为逐行慢处理）几乎总是比执行批量更改（其中一条语句一次性处理大量行）慢得多

使用一条语句即可轻松更改状态：

update oxy_emails_clean oec
    SET status = 3
from oxy_email oe
where oe.id = oec.id
  and oe.status = 3;

行的复制可以使用以下链接完成：

如何优化此过程的执行时间？不使用带有游标/循环的过程。相反，您可以使用两个单独的SQL语句，这两个SQL语句可能由一个链接的CTE粘在一起。如何优化此过程的执行时间？不使用带有游标/循环的过程。相反，您可以使用两个单独的SQL语句，它们可能由一个链接的CTE粘在一起