Store a 2D array in postgres - sql

Question

I have a 2D array which looks like below
[['2018-05-15', 6.7580658761256265], ['2018-05-16', 7.413963464926804], ['2018-05-17', 8.801776892107043], ['2018-05-18', 10.292505686766823], ['2018-05-19', 10.292505686766823], ['2018-05-20', 10.292505686766823], ['2018-05-21', 10.292505686766823]]
I want to store this 2D array in postgres.I checked postgres's documentation https://www.postgresql.org/docs/9.1/static/arrays.html and found the below example
CREATE TABLE sal_emp (
name text,
pay_by_quarter integer[],
schedule text[][]
);
INSERT INTO sal_emp
VALUES ('Bill',
ARRAY[10000, 10000, 10000, 10000],
ARRAY[['meeting', 'lunch'], ['training', 'presentation']]);
For a list that contains both of its values as string ['meeting', 'lunch'], we use text[][] But as you can see, I have one string and one float as a content of a list
['2018-05-15', 6.7580658761256265]
Then what do I set the column type as?

Answer 1

It's not an array anymore if the types are different. Arrays only can have one base type. You'll have to use an array of a composite type instead.
CREATE TYPE your_type AS (text_member text,
float_member float);
CREATE TABLE your_table
(your_type_column your_type[]);
INSERT INTO your_table
(your_type_column)
VALUES (array[row('2018-05-15',
6.7580658761256265)::your_type,
row('2018-05-16',
7.413963464926804)::your_type,
...
row('2018-05-21',
10.292505686766823)::your_type]);
But maybe consider not using arrays at all if possible, have another table and a normalized schema. Also consider using date instead of text if it's actually a date. (I just used text because you said it was a "string", though the sample data suggests differently.)