The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/13/sql-refreshmaterializedview.html Description:
Hi, it may seem obvious, but it took us TB of WALs and some time to identify the problem, why a bigger materialized view created much more WALs than a normal refresh. A concurrent refresh needs at least one unique index and no column of these indexes should be null: unique columns with null cannot identified as unchanged and will be replaced. I am not sure about the wording, but there should be a hint that this can be a problem. This might be ok for only a few rows but we had >14.000.000 rows and only a few thousand had all values set for the unique index. Hourly refresh, TB of WAL/day for just 4GB of database :-( This is at least valid for 11 - 13 Thanks :) Stefan
