Hello, Thank you to all who responded. There is a follow up question. Our admin tried the following: A host that wad been running postgresql11 was upgraded to Alma9 (from SL7) and postgresql15. They then built postgresql11 on that host from sources. Then they run pg_upgrade from 11 to 15. It worked and psql to db is not accompanied by "collation version" warning. This was unexpected to me based on my experience that I related on this thread. Is this a legit procedure? To remind, what did no work: - upgrade to 15 on SL7 host, setup stream, replication to Alma9 host. psql top replica complains about "The database was created using collation ..." Advice is appreciated P.S.: where I can still find postgresql11 RPMs for Alma9? Buiding from sourcres is OK, but a bit of a hassle. ________________________________________ From: Daniel Verite <daniel@xxxxxxxxxxxxxxxx> Sent: Monday, June 24, 2024 3:48 AM To: Dmitry O Litvintsev Cc: pgsql-generallists.postgresql.org Subject: Re: Help. The database was created using collation version 2.17, but the operating system provides version 2.34. [EXTERNAL] – This message is from an external sender Dmitry O Litvintsev wrote: > Just want to make clear (sorry I am slow on uptake). I should first > REINDEX and then ALTER DATABASE xxx REFRESH COLLATION VERSION, or > first ALTER and then REINDEX or does the order of these action > matter at all? The order does not matter. The ALTER DATABASE command will simply update the pg_database.datcollversion field with the current version of libc. That will stop the warning being issued, but it doesn't have any other concrete effect. Best regards, -- Daniel Vérité https://urldefense.proofpoint.com/v2/url?u=https-3A__postgresql.verite.pro_&d=DwIFaQ&c=gRgGjJ3BkIsb5y6s49QqsA&r=7PHi3TDlwkvpc07MjENbOxVFl0u_sEurf250JnUFWCU&m=F7VKeBFcE7ctVYy8fHvYvWPu4XkawA0hCuQOkYZk28e1uHpd_pb21GOrRMy9JB7a&s=M6qlhocjLWWgy8tVbTGTDEewC5JWHAfVztgV_XTx8Lg&e= Twitter: @DanielVerite