Hi On Tue, Dec 5, 2017 at 11:01 PM, Bruce Momjian <br...@momjian.us> wrote:
> As part of PGConf.Asia 2017 in Tokyo, we had an unconference topic about > zero-downtime upgrades. After the usual discussion of using logical > replication, Slony, and perhaps having the server be able to read old > and new system catalogs, we discussed speeding up pg_upgrade. > > There are clusters that take a long time to dump the schema from the old > cluster and recreate it in the new cluster. One idea of speeding up > pg_upgrade would be to allow pg_upgrade to be run in two stages: > > 1. prevent system catalog changes while the old cluster is running, and > dump the old cluster's schema and restore it in the new cluster > > 2. shut down the old cluster and copy/link the data files > When we were discussing this, I was thinking that the linking could be done in phase 1 too, as that's potentially slow on a very large schema. > > My question is whether the schema dump/restore is time-consuming enough > to warrant this optional more complex API, and whether people would > support adding a server setting that prevented all system table changes? I've certainly heard of cases where pg_upgrade takes significant amounts of time to run on very complex databases. -- Dave Page Blog: http://pgsnake.blogspot.com Twitter: @pgsnake EnterpriseDB UK: http://www.enterprisedb.com The Enterprise PostgreSQL Company
