KVP table vs. hstore - hstore performance (Was: Postgres NoSQL emulation)

Hi,

I am conducting a benchmark to compare KVP table vs. hstore and got
bad hstore performance results when the no. of records is greater than
about 500'000.

CREATE TABLE kvp ( id SERIAL PRIMARY KEY, key text NOT NULL, value text );
-- with index on key
CREATE TABLE myhstore ( id SERIAL PRIMARY KEY, obj hstore NOT NULL );
-- with GIST index on obj

Does anyone have experience with that?

Yours, Stefan