Re: [SQL] Better way to sort a JSONB array?
От | Steve Midgley |
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Тема | Re: [SQL] Better way to sort a JSONB array? |
Дата | |
Msg-id | CAJexoSKz36igt8CESipzf7Lm722=da2nuHxa7C2e-0GFt8xz+Q@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: [SQL] Better way to sort a JSONB array? (Michael Moore <michaeljmoore@gmail.com>) |
Ответы |
Re: [SQL] Better way to sort a JSONB array?
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Список | pgsql-sql |
On Mon, Aug 7, 2017 at 2:12 PM, Michael Moore <michaeljmoore@gmail.com> wrote:
json_table2 is declared as a variable in pgsql. It is not a jsonb table column. It is loaded from a statement like:
execute 'select jsonb_agg(row_to_json(zzz)) from (...extremely complex query goes here) zzz' into json_table2;Later, additional rows are added like:for a in select * from [table with the same columns as json_table_2]loopjson_table2 = coalesce (json_table2 || jsonb_agg(row_to_json (a)), jsonb_agg(row_to_json (a)) );end loop;So, because of the fact that the json_table2 is appended to in a random order, json_table2 now must be sorted.thanksOn Mon, Aug 7, 2017 at 1:51 PM, Steve Midgley <science@misuse.org> wrote:On Mon, Aug 7, 2017 at 1:13 PM, Michael Moore <michaeljmoore@gmail.com> wrote:This works, but surely there is a better way to do it:select jsonb_agg(row_to_json(alias)) from(Select * from jsonb_populate_recordset(null::tx_portal, json_table2) order by portal_name) alias into json_table2;It sorts the json_table2 array in "portal_name" order.I'm confused why you can't just pull portal_name from the json structure using "->"? For example, assuming your json structure that looks like:{"portal_name": "some data.."}And a table that looks like:| id | json_field |Wouldn't this sql work:select * from json_tableorder by json_field->'portal_name'
Can you provide the final structure of json_table2 in DDL or similar?
If "->" isn't right (b/c it's an array), would "->>[n]" work (if you know the array element you want to sort by - presumably "0")? That would sort by the first element in the array.
I'm just confused about your question (and knowing you know a ton about Postgres), as to why, once you have a stable table structure in json_table2, why you can't just use standard sql and json operators to pinpoint the data you want and order on it..
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