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
