PostgreSQL的日誌到另一個表與衝突

Question

我使用PostgreSQL 9.5，我嘗試插入使用BULK INSERT每天數百萬行：

INSERT INTO "tours" as cst ("adults","country_id", "price") 
VALUES (3, 129, 80), (2, 119,120) 
on conflict (adults, country_id) do 
    update set price = EXCLUDED.price, updated_at = now() 
    where excluded.price < cst.price 
RETURNING ID; 

如果價格較低，我會更新一行。我想爲未更新的日誌價格添加else條件。事情是這樣的：

INSERT INTO "tours" as cst ("adults","country_id", "price") 
VALUES (3, 129, 80), (2, 119,120) 
on conflict (adults, country_id) 
    case when excluded.price < cst.price 
     then 
     do update set price = EXCLUDED.price, updated_at = now() 
     else 
     INSERT INTO "tours_price_logging" (price, created_at) 
     values (EXCLUDED.price, now()) end; 

但我有錯誤這種情況：

ERROR: syntax error at or near "case" 

我想從插入取出條件where excluded.price < cst.price，並將這個邏輯trigger，但後來我會更新行的價格與價值從tours_price_logging和價格可能更多然後當前。

所以，我想使用upsert和批量插入日誌記錄。

Answer 1

您只需將您的CASE移入UPDATE。 「ON CONFLICT」可以做兩件事之一，沒有任何事情或更新。

...ON CONFLICT (adults, country_id) UPDATE SET price = CASE WHEN ... ; 

Answer 2

你需要一個觸發：

create or replace function before_update_on_tours() 
returns trigger language plpgsql as $$ 
begin 
    if new.price >= old.price then 
     insert into tours_price_logging (price, created_at) 
     values (new.price, now()); 
     return null; 
    end if; 
    return new; 
end $$; 

create trigger before_update_on_tours 
before update on tours 
for each row execute procedure before_update_on_tours(); 

當一個新的價格是不是比老觸發插入行的記錄表並返回null，所以沒有更新，將在完成低旅行團。 與觸發您的查詢應該是這樣的：

insert into tours as cst (adults,country_id, price) 
values (3, 129, 80), (2, 119, 90) 
on conflict (adults, country_id) do 
    update set price = excluded.price, updated_at = now() 
returning id;