På tirsdag 06. februar 2018 kl. 01:09:18, skrev David Fetter <da...@fetter.org <mailto:da...@fetter.org>>: Folks,
While chatting with Bruce about how to make something better than pg_upgrade, we (and by "we," I mean mostly Bruce) came up with the following. What needs improvement: - pg_upgrade forces a down time event, no matter how cleverly it's done. - pg_upgrade is very much a blocker for on-disk format changes. The proposal: - Add a new script--possibly Perl or Bash, which would: - Initdb a new cluster with the new version of PostgreSQL and a different port. - Start logical replication from the old version to the new version. - Poll until a pre-determined default amount of replication lag was observed, then: * Issue an ALTER SYSTEM on the new server to change its port to the old server's * Issue a pg_ctl stop -w to the old server * Issue a pg_ctl restart on the new server * Happiness! Assumptions underlying it: - Disk and similar resources are cheap enough for most users that doubling up during the upgrade is feasible. - The default upgrade path should require exactly one step. - Errors do not, by and large, have the capacity to violate an SLA. The proposal has blockers: - We don't actually have logical decoding for DDL, although I'm given to understand that Álvaro Herrera has done some yeoman follow-up work on Dimitri Fontaine's PoC patches. - We don't have logical decoding for DCL (GRANT/REVOKE) - Need to add support for decoding LargeObjects. -- Andreas Joseph Krogh
