On Fri, Jan 17, 2014 at 10:20 AM, Laurence Rowe <l...@lrowe.co.uk> wrote:
> I'm trying to unpack a json array into it's constituent text values so I can
> join them to a table. I can successfully unpack json values, but am having
> trouble converting these to text so I can cast them to the UUIDs needed for
> the join.
Here's another approach to implement json_array_elements_text, using
the field extraction operator to extract all fields one-by-one. But
for large arrays this is likely slower, as it needs to parse the whole
JSON string for each array element, leading to O(n^2) complexity.
CREATE FUNCTION json_array_elements_text(json) RETURNS SETOF text
IMMUTABLE LANGUAGE sql
AS $$ SELECT $1->>i FROM generate_series(0, json_array_length($1)-1) i; $$;
db=# select json_array_elements_text('["hello",1.3,"\u2603"]');
json_array_elements_text
--------------------------
hello
1.3
☃
Regards,
Marti
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