postgres更新加入慢性能

Question

我有以下 tables 并尝试从第二个 table 更新到第一个，似乎需要超过 15 分钟，我当时就把它杀了。

基本上只是试图将一个字段从 table 设置到另一个字段。两个 table 都有大约 250 万行。我们如何优化这个操作？

第一个table:

\d table1
                              Table "public.fa_market_urunu"
    Column    |            Type             | Collation | Nullable |        Default
--------------+-----------------------------+-----------+----------+-----------------------
 id           | character varying           |           | not null |
 ad           | character varying           |           |          |
 url          | character varying           |           |          |
 image_url    | character varying           |           |          |
 satici_id    | character varying           |           | not null |
 satici       | character varying           |           | not null |
 category_id  | character varying           |           |          |
 date_created | timestamp with time zone    |           | not null | now()
 last_updated | timestamp(3) with time zone |           | not null | now()
 fiyat        | double precision            |           |          |
Indexes:
    "tbl1_pkey" PRIMARY KEY, btree (id)
    "tbl1_satici" UNIQUE, btree (id, satici)
    "tbl1_satici_id" UNIQUE, btree (satici, id)
    "tbl1_satici_id_last_updated" UNIQUE, btree (satici, id, last_updated)
    "tbl1_satici_id_satici_key" UNIQUE CONSTRAINT, btree (satici_id, satici)
    "tbl1_satici_last_updated_id" UNIQUE, btree (satici, last_updated, id)
    "tbl1_last_updated" btree (last_updated)
    "tbl1_satici_category" btree (satici, category_id)
    "tbl1_satici_category_last_updated" btree (satici, category_id, last_updated)
    "tbl1_satici_last_updated" btree (satici, last_updated)

秒table:

\d table2
                Table "public.temp_son_fiyat"
 Column  |       Type        | Collation | Nullable | Default
---------+-------------------+-----------+----------+---------
 urun_id | character varying |           |          |
 satici  | character varying |           |          |
 fiyat   | double precision  |           |          |
Indexes:
    "ind_u" UNIQUE, btree (urun_id, satici)

我的操作：

UPDATE table1 mu
        SET fiyat = fn.fiyat
        FROM table2 AS fn
        WHERE mu.satici_id = fn.urun_id AND mu.satici = fn.satici;

Answer 1

发生这种情况是因为索引。 postgres 中的每次更新都被视为对该行的重新插入，而不管列是否更新，因此所有索引都会重新计算。为了使其更快，删除索引或交换到新的 table 会起作用（如果可能的话）。

postgres更新加入慢性能

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