On Fri, Mar 8, 2024 at 4:22 PM David Gauthier <dfgpostgres@xxxxxxxxx> wrote:
Here's the situation....- The DB contains data for several projects.- The tables of the DB contain data for all projects (data is not partitioned on project name or anything like that)- The "project" identifier (table column) exists in a few "parent" tables with many child... grandchild,... tables under them connected with foreign keys defined with "on delete cascade". So if a record in one of the parent table records is deleted, all of its underlying, dependent records get deleted too.- New projects come in, and old ones need to be removed and "archived" in DBs of their own. So there's a DB called "active_projects" and there's a DB called "project_a_archive" (identical metadata).- The idea is to copy the data for project "a" that's in "active_projects" to the "project_a_arhchive" DB AND delete the project a data out of "active_projects".- Leave "project_a_archive" up and running if someone needs to attach to that and get some old/archived data.The brute-force method I've been using is...1) pg_dump "active_projects" to a (huge) file then populate "project_a_archive" using that (I don't have the privs to create database, IT creates an empty one for me, so this is how I do it).2) go into the "project_a_archive" DB and run... "delete from par_tbl_1 where project <> 'a' ", "delete from par_tbl_2 where project <> 'a' ", etc... leaving only project "a" data in the DB.3) go into the "active_projects" DB and "delete from par_tbl_1 where project = 'a' ", etc... removing project "a" from the "active_projects DB.Ya, not very elegant, it takes a long time and it takes a lot of resources. So I'm looking for ideas on how to do this better.Related question...
The "delete from par_tbl_a where project <> 'a' " is taking forever. I fear it's because it's trying to journal everything in case I want to rollback. But this is just in the archive DB and I don't mind taking the risk if I can speed this up outside of a transaction. How can I run a delete command like this without the rollback recovery overhead ?
>(I don't have the privs to create database, IT creates an empty one for me, so this is how I do it).
That's a shame. You can do something similar with tablespaces
Template your existing schema to create a new schema for the project (pg_dump -s)
Create tablespace for this new project and schema
You can then move the physical tablespace to cheaper disk and use symbolic links or... archive and/or back it up at the schema level with pg_dump -n
...as long as you don't put anything in the public schema all you are really sharing is roles otherwise a bit like a separate database
