Always back up your databases before any upgrade. A failed upgrade without a backup can result in data loss.

Two approaches

Upgrade methods compared

Method	Downtime	Risk	Best for
Dump / restore	Minutes to hours	Low	Most users — safest path
pg_upgrade	Minutes (large DBs)	Medium	Large databases where dump is too slow

Method A — recommended

Dump and restore (safest path)

1
Dump all databases from old version

cmd.exe
# Dump all databases to a file:
C:\> pg_dumpall -U postgres -f C:\backup\all_dbs.sql
Password:
# Wait for completion (can take minutes to hours)
2
Install the new PostgreSQL version
Download and run the new installer. Install to a different directory (e.g. C:\Program Files\PostgreSQL8). Use a different port (e.g. 5433) during setup to avoid conflict with the old version still running.
3
Restore to the new version

cmd.exe
# Connect to new instance (port 5433) and restore:
C:\> psql -U postgres -p 5433 -f C:\backup\all_dbs.sql
Password:
4
Verify data and switch ports
Connect to the new instance, verify your data looks correct, then stop the old service, change the new service port to 5432, and start it. Update any connection strings in your applications.
5
Uninstall the old version
Once everything is confirmed working, uninstall the old PostgreSQL version from Settings → Apps.

Method B

pg_upgrade (in-place upgrade)

pg_upgrade copies or hard-links data files from the old cluster to the new one. It is faster than dump/restore for large databases but more complex to execute correctly.

cmd.exe — Administrator

# Run pg_upgrade from the new version bin directory:

C:\> "C:\Program Files\PostgreSQL\18\bin\pg_upgrade.exe"

-b "C:\Program Files\PostgreSQL\16\bin"

-B "C:\Program Files\PostgreSQL\18\bin"

-d "C:\Program Files\PostgreSQL\16\data"

-D "C:\Program Files\PostgreSQL\18\data"

--check

# Run without --check to perform the actual upgrade

Stop both PostgreSQL services before running pg_upgrade. The --check flag runs a dry run without modifying data.

Post-upgrade

Post-migration checks

cmd.exe

# Check new version:

C:\> psql -U postgres -c "SELECT version();"

PostgreSQL 18.3...

# List all databases:

C:\> psql -U postgres -l

# Run ANALYZE to update statistics:

C:\> vacuumdb -U postgres --all --analyze

FAQ

Migration questions

Can I upgrade from PostgreSQL 14 directly to 18?

Yes. Both methods (dump/restore and pg_upgrade) support skipping major versions. pg_upgrade can go from any supported older version directly to the new one. The dump/restore method always works regardless of version gap.

How long does the upgrade take?

Dump/restore time scales with database size — expect 10-30 minutes per 10 GB for typical workloads. pg_upgrade with hard-linking is nearly instant regardless of size, but requires additional steps and carries more risk.

Do my extensions need to be upgraded too?

After upgrading, run ALTER EXTENSION extension_name UPDATE; for each extension in each database. Or use vacuumdb --all --analyze which also handles extension updates in recent versions.

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