Re: Materialized views & dead tuples

On Tue, 2024-06-18 at 15:28 -0700, Wells Oliver wrote:
> Apologies for the daft question, but I am surprised to see materialized views
> show up in pg_stat_user_tables with lots of dead tuples. These are rematerialized
> nightly and, I thought, this had the effect of replacing/recreating them anew.
> Can someone shed some light on this?

It makes a difference if you use REFRESH MATERIALIZED VIEW or
REFRESH MATERIALIZED VIEW CONCURRENTLY.

The first statement will just discard the materialized table and create it anew,
and you will never see a dead tuple.
The second statement executes the query and updates the materialized table, which
can lead to dead tuples just like a normal UPDATE or DELETE.

Yours,
Laurenz Albe