create snapshot?

hi, i was wondering if there is something in postgresql like "create snapshot".
i once saw ti on friend's database (dont know what it was), and i really like
it.
snapshot is something like materialized view.
it is a physically existing table, with only select's allowable, and update
snapshot command which recreates the table using defined at "create snapshot"
selects.
this is especially usefull for data warehouses, but not only, and could greatly
improve performance of database system.
importnant thing is that snapshots are not only for one session.
they are difned, created, and stay on storage after closing session - till some
other sessions does make "drop snapshot".

i'm not sure if i'm clear, but ... let's hope so.

any way to do it in pgsql?

depesz

--
hubert depesz lubaczewski
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     najwspanialszą rzeczą jaką dało nam nowoczesne społeczeństwo,
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