What you need to know
Decide the independent rollback path before starting a PostgreSQL cluster upgraded with linked files.
Potentially affected
This applies to PostgreSQL 17 pg_upgrade planning. It addresses the link-mode rollback boundary, not every extension compatibility check or permission to upgrade an unsupported application stack.
DSE recommendation
DSE recommends writing the rollback decision before the upgrade begins: which untouched recovery copy exists, who can approve first startup, and what evidence must be reviewed at that gate.
Decide the independent rollback path before starting a PostgreSQL cluster upgraded with linked files.
Source facts
PostgreSQL 17 pg_upgrade offers link mode to avoid copying data files, reducing upgrade time and extra space compared with copying. The old and new data directories must share a filesystem for that mode. Crucially, once the upgraded new cluster is started, the old cluster is no longer usable with those linked files. The check option performs compatibility checks without changing data. Clone mode has different availability and old-cluster consequences, so the chosen mode matters to rollback design.
Source: PostgreSQL 17 — pg_upgrade.
Applicability
This applies to PostgreSQL 17 pg_upgrade planning. It addresses the link-mode rollback boundary, not every extension compatibility check or permission to upgrade an unsupported application stack.
DSE recommendation
DSE recommends writing the rollback decision before the upgrade begins: which untouched recovery copy exists, who can approve first startup, and what evidence must be reviewed at that gate. Run compatibility checks and a timed rehearsal using the intended mode. Do not describe the old data directory as the fallback after linked-file startup. Record filesystem prerequisites and restoration steps explicitly, along with the application checks needed before normal write traffic resumes.
Verification
Rehearse the upgrade on an isolated copy, retain check output, and verify the documented recovery path from an independent preserved copy. Confirm the team understands the point after which the old linked directory cannot serve as rollback. Record application and extension checks before approving the live plan.
Official reference
PostgreSQL 17 — pg_upgrade. Reviewed October 15, 2026.
Review the official source
PostgreSQL 17 — pg_upgrade · Verified October 15, 2026
Need help applying this guidance safely?
DSE can help confirm applicability, protect service continuity, and validate the result across physical security and IT systems.
Talk with DSE