Speeding up PostgreSQL dump/restore snapshots
19 comments
·July 5, 2025hadlock
nijave
Ideally off-site replica you fail over too and don't need to restore.
pg_restore will handle roles, indexes, etc assuming you didn't switch the flags around to disable them
If you're on EC2, hopefully you're using disk snapshots and WAL archiving.
Arbortheus
Offsite replica is only applicable if the cause is a failure of the primary. What if I’m restoring a backup because someone accidentally dropped the wrong table?
ants_everywhere
I would hope dropping a table on a production database is something that is code reviewed
pgwhalen
Of course that’s preferable, but OP is specifically asking about the cold restore case, which tends to pose different problems, and is just as important to maintain and test.
zie
What we do, is automated restores. We have a _hourly and an _daily restore that just happens via shell script.
We encourage staff to play with both, and they can play with impunity since it's a copy that will get replaced soon-ish.
This makes it important that both work reliably, which means we know when our backups stop working.
We haven't had a disaster recovery situation yet(hopefully never), but I feel fairly confident that getting the DB back shouldn't be a big deal.
forinti
If you can have a secondary database (at another site or on the cloud) being updated with streaming replication, you can switch over very quickly and with little fuss.
bityard
There needs to be a DBA version of the saying, "RAID is not a backup"
SoftTalker
Which is what you must do if minimizing downtime is critical.
And, of course, your disaster recovery plan is incomplete until you've tested it (at scale). You don't want to be looking up Postgres documentation when you need to restore from a cold backup, you want to be following the checklist you have in your recovery plan and already verified.
zie
Sure, but there are lots of failure modes where the failure goes with the streaming replication and all instances are trashed.
WJW
> in the 100-2TB range where probably most businesses lie
Assuming you mean that range to start at 100GB, I've worked with databases that size multiple times but as a freelancer it's definitely not been "most" businesses in that range.
bitbasher
pg_bulkload[1] has saved me so much time cold restoring large (1+ TB) databases. It went from 24-72 hours to an hour or two.
I also recommend pg_repack[2] to squash tables on a live system and reclaim disk space. It has saved me so much space.
itsthecourier
I'm just checking it now
do you export the data with this and then import it in the other db with it?
or do you work with existing postgres backups?
bitbasher
There’s a number of options. I mainly work with gzipped CSV dumps that I need to restore.
inslee1
Slightly related but how does WAL-G stack up as far as backup/restoration options go for Postgres? https://github.com/wal-g/wal-g
jpalawaga
Postgres backups are tricky for sure. Even if you have a DR plan you should assume your incremental backups are no good and you need to restore the whole thing from scratch. That’s your real DR SLA.
If things go truly south, just hope you have a read replica you can use as your new master. Most SLAs are not written with 72h+ of downtime. Have you tried the nuclear recovery plan, from scratch? Does it work?
moribunda
While these optimizations are solid improvements, I was hoping to see more advanced techniques beyond the standard bulk insert and deferred constraint patterns. These are well-established PostgreSQL best practices - would love to see how pgstream handles more complex scenarios like parallel workers with partition-aware loading, or custom compression strategies for specific data types.
One thing that's sorely needed in the official documentation is a "best practice" for backup/restore from "cold and dark" where you lose your main db in a fire and are now restoring from offsite backups for business continuity. Particularly in the 100-2TB range where probably most businesses lie, and backup/restore can take anywhere from 6 to 72 hours, often in less than ideal conditions. Like many things with SQL there's many ways to do it, but an official roadmap for order of operations would be very useful for backup/restore of roles/permissions, schema etc. You will figure it out eventually, but in my experience the dev and prod db size delta is so large many things that "just work" in the sub-1gb scale really trip you up over 200-500gb. Finding out you did one step out of order (manually, or badly written script) halfway through the restore process can mean hours and hours of rework. Heaven help you if you didn't start a screen session on your EC2 instance when you logged in.