How to sort a PostgreSQL JSON field [duplicate] - sql

Question

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How to reorder array in JSONB type column
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JSONB column: sort only content of arrays stored in column with mixed JSONB content
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Closed 4 years ago.
I have some table with json field. I want to group & count that field to understand its usage frequency. But the data in this field is stored in a random order, so I can get the wrong result. That's why I've decided to sort that field before grouping, but I failed. How can I do it?
JSON_FIELD
["one", "two"]
["two"]
["two", "one"]
["two"]
["three"]
I've tried this code:
SELECT JSON_FIELD, COUNT(1) FROM my_table GROUP BY JSON_FIELD;
But the result w/o sorting is wrong:
JSON_FIELD COUNT
["one", "two"] 1
["two"] 2
["two", "one"] 1
["three"] 1
But if I could sort it somehow, the expected (and correct) result would be:
JSON_FIELD COUNT
["one", "two"] 2
["two"] 2
["three"] 1
My question is very familiar to How to convert json array into postgres int array in postgres 9.3

Answer 1

A bit messy but works:
SELECT ja::TEXT::JSON, COUNT(*)
FROM (
SELECT JSON_AGG(je ORDER BY je::TEXT) AS ja
FROM (
SELECT JSON_ARRAY_ELEMENTS(j) je, ROW_NUMBER() OVER () AS r
FROM (
VALUES
('["one", "two"]'::JSON),
('["two"]'),
('["two", "one"]'),
('["two"]'),
('["three"]')
) v(j)
) el
GROUP BY r
) x
GROUP BY ja::TEXT
Result:
BTW the casting of JSON values to TEXT is because (at least in PG 9.3) there are no JSON equality operators, so I cast to TEXT in order to be able to do GROUP or ORDER BY, then back to JSON.