Re: Hstore VS. JSON

On 07/16/2013 11:05 AM, Niels Kristian Schjødt wrote:
> Hi,
>
> I'm in the process of implementing a table for storing some raw data in the format of a hash containing one level of keys and values. The hash can be quite big (up to 50 keys pointing at values varying from one to several hundred characters)
>
> Now, I'm in doubt whether to use JSON or Hstore for this task. Here is the facts:
>
> - I'm not going to search a lot (if any) in the data stored in the column, i'm only going to load it out.
> - The data is going to be heavily updated (not only inserted). Keys and values are going to be added/overwritten quite some times.

In both cases, each hstore/json is a single datum, and updating it means
writing out the whole datum - in fact the whole row containing the datum.

> - My database's biggest current issue is updates, so i don't want that to be a bottle neck.
> - I'm on postgresql 9.2
>
> So, question is: Which will be better performance wise, especially for updates? Does the same issues with updates on the MVCC structure apply to updates in Hstore? What is taking up most space on the HDD?
>

MVCC applies to all updates on all kinds of data. Hstore and JSON are
not different in this respect.

You should test the storage effects with your data. On 9.2 for your data
hstore might be a better bet, since in 9.2 hstore has more operators
available natively.

cheers

andrew