我剛剛從試驗機轉儲數據庫到本地機器上運行,下面我查詢: SELECT advert_id,A.category_id,A.subcategory_id,subcategory,model_id,model,make,price,price2,gst,cndtn,currency,photo_id, SUM(S.visits) AS visits
FROM adverts A
LEFT JOIN
我對Postgres的表有一個有趣的案例與選擇: advert (~2.5 million records)
id serial,
user_id integer (foreign key),
...
這是我的選擇: select count(*) from advert where user_id in USER_IDS_ARRAY
如果USER_IDS_A
我的表中有一個JsonB列,它包含分層信息。現在 MyTable (id uuid, indexes jsonb, content bytea)
如果我創建一個CTE說 WITH RECURSIVE hierarchy(pid, id, content) AS (
--load first parents
SELECT t.indexes ->> 'parentId' as
我正在嘗試使用EXPLAIN優化我的MySQL查詢。這裏是一個非常簡單地查詢的示例: SELECT ID, Date, SenderID, Message FROM messages WHERE ReceiverID = '1000' ORDER BY ID DESC LIMIT 25;
當我觀看解釋它示出了: +----+-------------+-----------+------+--