[英]Postgres JSONB query simplification
我有一些工作代碼從表單表中提取記錄,其中 'mail@example.com' 在 JSONB 字段之一、 column_a
、 column_b
、 column_c
或column_d
顯示為 JSON 值。
SELECT *
FROM forms f
WHERE exists (SELECT *
FROM jsonb_each_text(f.column_a) as e(ky,val)
WHERE e.val = 'mail@example.com')
UNION
SELECT *
FROM forms f
WHERE exists (SELECT *
FROM jsonb_each_text(f.column_b) as e(ky,val)
WHERE e.val = 'mail@example.com')
UNION
SELECT *
FROM forms f
WHERE exists (SELECT *
FROM jsonb_each_text(f.column_c) as e(ky,val)
WHERE e.val = 'mail@example.com')
UNION
SELECT *
FROM forms f
WHERE exists (SELECT *
FROM jsonb_each_text(f.column_d) as e(ky,val)
WHERE e.val = 'mail@example.com');
列中的 JSON 類似於:
{ "xyz":"mail@example.com", "def":"mail2@example.com", "lmn":"mail3@example.com" }
盡管代碼有效,但它看起來高度重復/冗長。 鑒於我無法更改 JSON 結構,是否有更簡潔的方法來構建此查詢,以及我應該為這些列構建哪些索引以獲得最佳性能?
為什么不使用or
?
SELECT f.*
FROM forms f
WHERE EXISTS (SELECT *
FROM jsonb_each_text(f.column_a) as e(ky,val)
WHERE e.val = 'mail@example.com'
) OR
EXISTS (SELECT *
FROM jsonb_each_text(f.column_b) as e(ky,val)
WHERE e.val = 'mail@example.com'
) OR
. . .
據推測,這也消除了重復消除的需要,因此查詢也應該更快。
編輯:
如果需要源,可以使用相關子查詢:
SELECT f.*
FROM (SELECT f.*,
EXISTS (SELECT *
FROM jsonb_each_text(f.column_a) as e(ky,val)
WHERE e.val = 'mail@example.com'
) as in_column_a,
EXISTS (SELECT *
FROM jsonb_each_text(f.column_b) as e(ky,val)
WHERE e.val = 'mail@example.com'
) as in_column_b,
. . .
FROM forms f
)
WHERE in_column_a OR in_column_b OR . . .
這不是很有效,因為它在找到匹配時不會短路評估。 另一方面,它列出了所有匹配的列。
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