On 2021-Mar-18, Stephen Frost wrote: > * Alvaro Herrera (alvhe...@alvh.no-ip.org) wrote: > > Patch 10 uses the term "WAL-skip relations". What does that mean? Is > > it "relations that are not WAL-logged"? I suppose we already have a > > term for this; I'm not sure it's a good idea to invent a different term > > that is only used in this new place. > > This is discussed in src/backend/access/transam/README, specifically the > section that talks about Skipping WAL for New RelFileNode. Basically, > it's the 'wal_level=minimal' optimization which allows WAL to be > skipped.
Hmm ... that talks about WAL-skipping *changes*, not WAL-skipping *relations*. I thought WAL-skipping meant unlogged relations, but I understand now that that's unrelated. In the transam/README, WAL-skip means a change in a transaction in a relfilenode that, if rolled back, would disappear; and I'm not sure I understand how the code is handling the case that a relation is under that condition. This caught my attention because a comment says "encryption does not support WAL-skipped relations", but there's no direct change to the definition of RelFileNodeSkippingWAL() to account for that. Perhaps I am just overlooking something, since I'm just skimming anyway. -- Álvaro Herrera Valdivia, Chile
