Hi Michael, I first use initdb, and set wal_log_hints=off, data_checksums=off, and full_page_writes=on. Starting pg and running for a while.
Then switch over happened, I used the following commands: 1. Old master postgresql.conf set wal_log_hints=on, then start and stop pg. 2. using pg_rewind --target-pgdata=OldMaster --source-server=NewMaster (no error, old master's wal_log_hints has been set to on) I wonder if this could lead to data corruption. On Tue, Feb 18, 2025 at 2:27 PM Michael Paquier <michael.paqu...@gmail.com> wrote: > On Mon, Jun 5, 2017 at 9:37 AM, Dylan Luong <dylan.lu...@unisa.edu.au> > wrote: > > pg_rewind requires that the target server either has the wal_log_hints > > option enabled in postgresql.conf or data checksums enabled when the > cluster > > was initialized with initdb. > > Yes, this is to make sure that you don't finish with a corrupted > target server if a hint bit is set on a page after a checkpoint. Any > of those options make sure that a full-page write is generated in this > case. > > > What is the difference between the two options? > > Data checksums calculate 2 bytes of checksum data and write it to each > page that is evicted from shared buffers. Each page read from disk has > its checksum checked. In some workloads, like a heavy read load where > a lot of page evictions happen, this can induce a couple of percents > of performance lost. In my own experience, that's 1~2%. > > > What are the advantages and disadvantages between the two? > > Which one is the the preferred option? > > If you care more about performance or if you use a file system that > has its own block-level checksum, wal_log_hints would be preferred. > Data checksums offer more guarantees in terms of integrity though when > looking for corrupted data. Things get found more quickly. > -- > Michael > > > -- > Sent via pgsql-general mailing list (pgsql-gene...@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > > >
