All Your GUCs in a Row: ignore_invalid_pages

A deep dive into PostgreSQL's ignore_invalid_pages GUC parameter — what it does, why the PANIC it suppresses occurs, and when (if ever) to use it. During WAL replay on standbys or restored backups, PostgreSQL tracks references to pages that don't exist in an in-memory hash table. If any remain unresolved at the consistency point, it emits a PANIC. ignore_invalid_pages downgrades those two PANICs to WARNINGs, allowing the server to start — but without repairing anything. The resulting database may have heap tuples without index entries, stale visibility info, and unknown data loss. The recommended use is strictly last-resort: set it on a scratch copy, take a pg_dump of what's readable, identify damaged relations via pg_filenode_relation() and pg_amcheck, then discard the cluster. For standbys, re-cloning with pg_basebackup is always preferable.

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