The idea of allowing a WHERE clause to be appended to REFRESH MATERIALIZED VIEW seems useful.
It would enable those that know well the pattern of data modification in their underlying use case to schedule delta-updates (say, from crontab). And also it would be a useful as a foundation for more ambitious ideas. For example, some folk can/wish to do something entirely custom that is trigger-based. Others such as Nico's have toolkits that intend to cover quite a lot of the automagical refresh cases (see this other thread https://www.postgresql-archive.org/Query-Rewrite-for-Materialized-Views-FDW-Extension-td6015235.html), and it allows the data to remain in an MVIEW to boot, rather than forcing them to use normal tables instead. It could also be the foundation for something much more integrated such as Corey's CONTINUOUS MATERIALIZED VIEW concept. So I'm certainly supportive of the idea. -- Sent from: http://www.postgresql-archive.org/PostgreSQL-hackers-f1928748.html
