Robert Haas wrote: > On Sun, Apr 11, 2010 at 10:26 AM, Heikki Linnakangas > <heikki.linnakan...@enterprisedb.com> wrote: >> Robert Haas wrote: >>> 2010/4/10 Andrew Dunstan <and...@dunslane.net>: >>>> Heikki Linnakangas wrote: >>>>> 1. Keep the materialized view up-to-date when the base tables change. >>>>> This can be further divided into many steps, you can begin by supporting >>>>> automatic updates only on very simple views with e.g a single table and >>>>> a where clause. Then extend that to support joins, aggregates, >>>>> subqueries etc. Keeping it really limited, you could even require the >>>>> user to write the required triggers himself. >>>> That last bit doesn't strike me as much of an advance. Isn't the whole >>>> point >>>> of this to automate it? Creating greedy materialized views is usually not >>>> terribly difficult now, but you do have to write the triggers. >>> Yeah, I agree. >> It doesn't accomplish anything interesting on its own. But if you do the >> planner changes to automatically use the materialized view to satisfy >> queries (item 2. in my previous email), it's useful. > > But you can't do that with a snapshot view, only a continuous updated one.
A materialized view with manually-defined triggers to keep it up-to-date is a continuously updated one. Other DBMSs allow that with snapshot views too, you just don't get totally up-to-date results, but I not sure we want to go there. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
