We have wal_log_hints = off. Then I thought hint bits are never WAL logged. Or am I missing the part - they are, upon first read ?
Thanks again Rado On Wed, May 19, 2021 at 3:56 PM Laurenz Albe <laurenz.a...@cybertec.at> wrote: > On Wed, 2021-05-19 at 14:16 +0300, Radoslav Nedyalkov wrote: > > Hello Forum, > > I know it sounds weird but we have faced it a couple of times already > and have no idea. > > We're trying to establish logical replication from RDS(10.9) to > RDS(12.5). > > We're adding tables to the publication one by one. > > During the initial copy for some tables we experience huge WAL > generation on the source db. > > From 0.5mb/s it jumps to 15MB/s. > > This happens when a copy just started or in the middle or at the end. > > WAL generation causes service statements to wait on WALWriteLock causing > high response time. > > > > Any idea how the initial copy can cause WAL generation ?! > > I don't know how much RDS is like PostgreSQL, but on PostgreSQL this could > be > the setting of hint bits for new rows that have never been read before. > > Yours, > Laurenz Albe > -- > Cybertec | https://www.cybertec-postgresql.com > >
