From 06ac3d0ebc1a212ec022640a29beae39136a955c Mon Sep 17 00:00:00 2001 From: John Naylor Date: Wed, 22 Jul 2026 09:32:56 -0400 Subject: [PATCH v1] pg_upgrade: check for arrays over system types with unstable OIDs Array values embed their element type's OID, and pg_upgrade does not rewrite user data. The information_schema domains get new OIDs in every major version, so a stored array over one -- created, for example, by aggregating an information_schema query into a table -- comes through the upgrade with a dangling element OID. Whole-array reads and pg_dump of the upgraded cluster then fail with "cache lookup failed for type N"; if the OID has meanwhile been reassigned, the values are misread instead. The data type checks miss this because nothing flags the domain itself: domain storage is just the base type, so the recursive expansion that catches arrays over flagged types never reaches it. Add a check for arrays whose element type lacks a hand-assigned OID (10000 and up, not stable across major versions), including anything in information_schema in case it was dropped and reloaded. Back-patch to all supported branches. --- src/bin/pg_upgrade/check.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/src/bin/pg_upgrade/check.c b/src/bin/pg_upgrade/check.c index 2155b01b11f..0a00a339012 100644 --- a/src/bin/pg_upgrade/check.c +++ b/src/bin/pg_upgrade/check.c @@ -127,6 +127,31 @@ static DataTypesUsageChecks data_types_usage_checks[] = .threshold_version = ALL_VERSIONS }, + /* + * Array values embed their element type's OID (ARR_ELEMTYPE). System + * types without hand-assigned OIDs (10000 and up) do not keep the same + * OID across major versions, so stored arrays over them would point at + * the wrong type after an upgrade. As above, the information_schema test + * covers a dropped-and-reloaded information_schema. + */ + { + .status = gettext_noop("Checking for arrays over system types with unstable OIDs in user tables"), + .report_filename = "tables_using_system_arrays.txt", + .base_query = + "SELECT t.oid FROM pg_catalog.pg_type t " + "JOIN pg_catalog.pg_type e ON t.typelem = e.oid " + "LEFT JOIN pg_catalog.pg_namespace n ON e.typnamespace = n.oid " + " WHERE t.typtype = 'b' AND " + " ((e.oid >= 10000 AND e.oid < 16384) " + " OR n.nspname = 'information_schema')", + .report_text = + gettext_noop("Your installation contains arrays over system types with unstable OIDs\n" + "in user tables. Array values embed the element type's OID, so this\n" + "cluster cannot currently be upgraded. You can drop the problem\n" + "columns, or change them to another data type, and restart the upgrade.\n"), + .threshold_version = ALL_VERSIONS + }, + /* * pg_upgrade only preserves these system values: pg_class.oid pg_type.oid * pg_enum.oid -- 2.55.0