3

Let's assume we have a table where it has two columns, one an ID and one an hstore column, which stores key/value pairs.

You could query that column as such:

SELECT name, attributes->'device' as device
FROM products
WHERE attributes->'edition'= 'ebook'

Can you create a view for this table where the keys/values appear as columns in the view instead of all in the hstore column?

Example: I have an hstore key where it might have the key of amenity. I want to create a view showing the the ID and the amenity values in a new view.

3

Sure you can.

CREATE VIEW v_ebooks AS
SELECT products_id, attributes->'device' AS device
FROM   products
WHERE  attributes->'edition'= 'ebook';

SQL Fiddle demo.

But only for a static set of columns. Dynamic output of all possible attributes in an hstore column conflicts with the requirement that the return type has to be declared at creation time.

This later answer provides a completely dynamic solution (in two steps):

  • Thanks Erwin. So does that mean if all keys are not present in all hstore columns, then an issue may arise? – code base 5000 Feb 10 '14 at 11:33
  • @josh1234: Columns will just be NULL for rows where the key is not found. – Erwin Brandstetter Feb 10 '14 at 15:04

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