string_to_array eats too much memory?

Hi,

I'm playing with GIN to make a full text search system. GIN comes with
built-in TEXT[] support and I use string_to_array() to make a
TEXT[]. Problem is, if there's large number of array elemets,
string_to_array() consumes too much memory. For example, to make ~70k
array elements, string_to_array seems to eat several Gig bytes of
memory. ~70k array elements means there are same number of words in a
document which is not too big in a large text IMO.

Comments?
--
Tatsuo Ishii
SRA OSS, Inc. Japan