On 16 November 2012 11:25, Kevin Grittner <kgri...@mail.com> wrote: >>> 16. To get new data into the MV, the command is LOAD MATERIALIZED >>> VIEW mat view_name. This seemed more descriptive to me that the >>> alternatives and avoids declaring any new keywords beyond >>> MATERIALIZED. If the MV is flagged as relisvalid == false, this >>> will change it to true. >> >> UPDATE MATERIALIZED VIEW was problematic? > > Not technically, really, but I saw two reasons that I preferred LOAD MV: > > 1. It seems to me to better convey that the entire contents of the MV > will be built from scratch, rather than incrementally adjusted. > 2. We haven't hashed out the syntax for more aggressive maintenance of > an MV, and it seemed like UPDATE MV might be syntax we would want to > use for something which updated selected parts of an MV when we do. > >> Does LOAD automatically TRUNCATE the view before reloading it? If not, >> why not? > > It builds a new heap and moves it into place. When the transaction > running LMV commits, the old heap is deleted. In implementation it is > closer to CLUSTER or the new VACUUM FULL than TRUNCATE followed by > creating a new table. This allows all permissions, etc., to stay in > place.
This seems very similar to the REPLACE command we discussed earlier, except this is restricted to Mat Views. If we're going to have this, I would prefer a whole command. e.g. REPLACE matviewname REFRESH that would also allow REPLACE tablename AS query Same thing under the covers, just more widely applicable and thus more useful. Either way, I don't much like overloading the use of LOAD, which already has a very different meaning. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
