Fix the pg_shdepend rows and harden the enable, disable and drop paths.

[ibrarahmad]

Problem

Large objects in lolor storage are rows in ordinary tables, but inv_create() still called recordDependencyOnOwner() for them with the OID of lolor.pg_largeobject as the classId. pg_shdepend only understands catalogs, so any role that ever created a large object cannot be dropped: in that database DROP ROLE fails with "unrecognized object class", from any other database it reports "owner of objects in database X". The rows were never cleaned up either, because inv_drop() deleted with PERFORM_DELETION_SKIP_ORIGINAL, which leaves the shared dependency behind.

Removing the rows opens the opposite gap. Without them DROP ROLE, REASSIGN OWNED and DROP OWNED cannot see objects in lolor storage, so a role that owns them or appears in their ACL can be dropped without a warning. The next migrate_to_native() then tries to record the dependency for the dead role inside shdepLockAndCheckObject() and dies with "role N was concurrently dropped", part way through the copy, and since DROP EXTENSION runs that migration the extension cannot be dropped either.

The paths that remove or switch the extension have related holes. The cleanup trigger fired only for DROP EXTENSION, so DROP SCHEMA lolor CASCADE and DROP OWNED BY the extension owner reached the extension through the dependency cascade, destroyed the large objects with the lolor tables and left pg_catalog without a working lo_open(). enable(), disable() and is_enabled() matched on proname in any schema, so a function named lolor_lo_open in any schema a user could write to wedged lolor into a permanent "inconsistent state" that also blocked DROP EXTENSION. And a rename keeps the function OID, so after enable() or disable() a session that had already resolved lo_open() kept calling the previous implementation; libpq caches the OIDs per connection as well.

Fix

Stop recording the pg_shdepend rows, and have the upgrade script delete the ones already present, scoped to the current database. Add lolor.check_orphans(), which lists objects whose owner, grantee or grantor no longer exists and which reference is dangling, and lolor.fix_orphans(new_owner), which reassigns a dead owner and rewrites the ACL the way REASSIGN OWNED does: the dead owner is replaced as grantee and grantor so grants it made survive, entries that still name a missing role are dropped, and each (grantee, grantor) pair becomes exactly one aclitem with the grant option kept per privilege, since GRANT and REVOKE update only the first matching entry. The up-front check in migrate_to_native() that refuses with the offending OIDs comes with the migration rewrite in #56.

Re-create the cleanup trigger for the DROP EXTENSION, DROP SCHEMA and DROP OWNED tags and recognise all three spellings in the C function. A plain DROP SCHEMA is left alone, since it is RESTRICT and gets rejected anyway. Make enable(), disable() and is_enabled() probe exact signatures in pg_catalog with to_regprocedure(). Add lolor._require_no_other_sessions(), which counts client backends in the current database the way ALTER DATABASE RENAME does, and call it from enable() and disable() so they refuse while another session is connected; the calling session is told to reconnect. #56 adds the same call to both migrations.

Tests

Regression: orphaned owner, grantee and grantor cases, fix_orphans() with a grant chain, a merge into the new owner's entry and mixed grant options, name squatting, DROP SCHEMA with and without CASCADE. TAP: t/008_drop_paths.pl for DROP SCHEMA CASCADE, DROP OWNED BY and the sole-session refusal.

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📝 Walkthrough

Walkthrough

The 1.3.0 update adds large-object orphan inspection and repair, expands extension cleanup for additional drop commands, and changes function switching to check exact signatures and require other client sessions to disconnect.

Changes

lolor 1.3.0 behavior and migration

Layer / File(s)	Summary
Orphaned ownership and ACL repair lolor--1.2.2--1.3.0.sql, src/lolor_inv_api.c, sql/lolor.sql, README.md, docs/lolor_release_notes.md	Adds functions to find and repair missing owner, grantee, and grantor roles. Removes stale shared-dependency rows for the current database and changes how lolor objects record and remove ownership dependencies. Regression tests cover permissions and orphan repair. The documentation describes role-management limitations and the release cleanup.
Drop-path handling src/lolor.c, lolor--1.2.2--1.3.0.sql, t/008_drop_paths.pl, sql/lolor.sql	The event trigger recognizes DROP EXTENSION lolor, DROP SCHEMA lolor CASCADE, and DROP OWNED BY the extension owner. Tests check cleanup, function restoration, and large-object preservation. The node maximum now uses LOLOR_MAX_NODE_ID.
Function checks and session restrictions lolor--1.2.2--1.3.0.sql, t/008_drop_paths.pl, sql/lolor.sql, docs/pg_upgrade_with_lolor.md	is_enabled(), enable(), and disable() probe exact pg_catalog signatures. Switching refuses to run while other client sessions are connected and reports that clients should reconnect after a successful switch. Tests and upgrade instructions cover these conditions.

Priority: ➖ Normal

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to a727e

Orphan repair now rebuilds each role pair's permissions as a single entry, including mixed grant-option cases, so a later REVOKE cannot miss a privilege. No outstanding merge-blocking issue was found in the lifecycle, drop-path or repair changes.

Architecture Summary

Architecture risk: 🔵 Low · up to a727e

The change affects 6 systems.

Changed systems: lolor--1.2.2--1.3.0.sql, sql, docs, src, README.md, t

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — lolor--1.2.2--1.3.0.sql (service) was modified; 1 changed file maps to changed impact.
• observed — sql (service) was modified; 1 changed file maps to changed impact.
• observed — docs (service) was modified; 2 changed files map to changed impact.
• observed — src (service) was modified; 2 changed files map to changed impact.

Before / after behavior

• observed — Modified behavior in README.md: The Limitations section adds session-connection and reconnect requirements for lolor.enable() and lolor.disable(), describes how role-management commands leave lolor object ownership and ACL references untouched, and documents the risk that role OID reuse can silently associate orphaned objects with a new role.
• observed — Modified behavior in docs/pg_upgrade_with_lolor.md: The instructions now require reconnecting client sessions after the lolor switch and explain that libpq caches the resolved pg_catalog.lo_* function OIDs for a connection, so existing sessions may keep calling the previous implementation.
• observed — Modified behavior in src/lolor.c: Added catalog, table-access, extension, ACL, and function-OID headers required by the new catalog lookups and drop detection.
• observed — Modified behavior in src/lolor.c: The lolor.node maximum changes from the literal 16 to LOLOR_MAX_NODE_ID.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 4 files. (3 skipped: 3 …
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The description clearly explains the pg_shdepend cleanup, lifecycle hardening, drop-path handling, orphan repair functions, and related tests. It is directly related to the changeset.
Title check	✅ Passed	The title concisely identifies the pg_shdepend fix and the hardening of enable, disable, and drop paths. These are the primary changes in the pull request.

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[danolivo]

Generally, current approach (and I should confess it is mia culpa) is wrong.

At first, the LOLOR extension must be loaded on startup. It is unsafe to let the instance start and later detect that some key routines don't have linked binaries.

Second, an object_access_hook must control any DROP command. At any backend, auxiliary process or worker, it checks that lolor is removed with the migration done (use a static flag to detect it) and cancels (an allow_unsafe_drop GUC might optionally disable it) any attempt if not.

Third, migrate_from_native must not be executed inside the apply worker. It is dangerous and not portable to other LR plugins. Instead, the node that initiated it should coordinate the migration as a single transaction. Doing it via an LR wire isn't correct since migration to the catalogue is not replicated.

[ibrarahmad]

Agree with preload and the OAT_DROP hook. Two things I would change.

A static flag is per backend: another session's migration will not set it, and a rollback after setting it leaves it set. Check real state instead, lolor storage empty and the _orig functions gone, which is what is_enabled() already probes.

A single cross-node transaction means PREPARE TRANSACTION on every node and COMMIT PREPARED from a coordinator, and max_prepared_transactions defaults to 0. I would rather refuse migrate_from_native() inside an apply worker, run it on each node directly, and compare lolor.digest() before resuming writes. Is that enough, or do you mean full 2PC?

[danolivo]

Agree with preload and the OAT_DROP hook. Two things I would change.

A static flag is per backend: another session's migration will not set it, and a rollback after setting it leaves it set.

In general, migration tools exist to prevent accidental deletion of LOs that usually contain critical data. They also provide a way to safely remove LOLOR if necessary, without breaking queries or the catalogue.

So, not sure what 'another session' migration might be about. According to the design, migration happens outside of any load. If we need to check it in advance, let's introduce it in this PR.
Any transfer from/to catalogue tables and extension ones, as well as (and even more dangerous) catalogue function replacements, must not be allowed. Cache invalidation mechanism is not strict enough to make it in a fully consistent and atomic way.

[ibrarahmad]

Agreed on the principle, and I will add the check here. enable(), disable() and both migrations will refuse while any other client session is connected to the database, the same rule as ALTER DATABASE RENAME, with the count in the DETAIL. I verified the cache problem you describe: a rename keeps the function OID, so after disable() a session that already resolved lo_open keeps calling lolor's implementation under the old OID. Refusing is the only clean answer for other sessions; the calling session still gets the reconnect notice.

On the static flag, my point was not concurrent load. The DROP usually runs in a different backend from the one that ran the migration, or the same one after reconnecting, so a per-backend flag cannot know. The OAT_DROP hook should check catalog state instead: lolor storage empty and the _orig functions gone. I will do the preload plus hook change as the follow-up to this PR unless you would rather have it here.

[ibrarahmad]

The preload and drop hook change is up as #58, stacked on #56. It checks the catalog state at deletion time instead of a static flag, and refuses enable(), disable() and the migrations outside a client session so replicated DDL cannot run them in an apply worker.

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Inline comments:
Review comments at @lolor--1.2.2--1.3.0.sql:
- Around line 112-121: Update the ACL aggregation around aclexplode and
makeaclitem to fold generated ACL items with pg_catalog.aclinsert for each
grantee and grantor pair. Remove is_grantable-based grouping and avoid combining
privileges with different grantability into one makeaclitem call; preserve the
existing owner remapping.

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[danolivo]

I verified the cache problem you describe

Sorry, I don't understand. It is not a subject for verification; it is just a registered, reproducible fact that vanilla Postgres has and will have:

https://www.postgresql.org/message-id/flat/f618b3d6-13ab-4898-9569-1e2913c01360%40gmail.com

I vaguely remember also some visibility nuances between the catalog and plain tables. So, migration between the system catalog and user space is dangerous, and we shouldn't allow it at all,

[danolivo]

The DROP usually runs in a different backend from the one that ran the migration

Yeah, my point was for the case when the user forces DROP even if it meanders multi-gigabyte migration.
If we do it in a separate backend, we can always observe the extension state, the OID of lo_open, for example, to be sure the migration has happened or not.

[ibrarahmad]

Yes. #58 does exactly that at deletion time: pg_catalog.lo_open_orig must be gone and lolor.pg_largeobject_metadata empty, checked from whichever backend runs the drop.

[ibrarahmad]

On the thread: that is the case these PRs guard against, a session with an open transaction keeps the old function. It is why enable(), disable() and both migrations now refuse unless they are the only client session in the database, and why the caller is told to reconnect. With no other session there is nobody left to hold a stale version. Without any migration there is no supported way to get objects out of lolor storage before the drop, which is what the hook has to verify.

[ibrarahmad]

On the owner: #56 copies the metadata tuple with its original lomowner and lomacl and calls recordDependencyOnOwner() and recordDependencyOnNewAcl() for that owner, the same calls LargeObjectCreate() makes. The migrating user never becomes the owner. The regression test checks the owner and the pg_shdepend rows after a round trip. Going through lo_create() under SET ROLE would lose sparse pages and grant options, so I kept the tuple copy.

On the drop: agreed, and #58 now does exactly that. The event trigger only puts the pg_catalog names back; it no longer migrates anything. The object access hook refuses DROP EXTENSION, DROP SCHEMA lolor CASCADE, DROP OWNED BY and any other path while objects remain in lolor storage or lolor is enabled, so migrate_to_native() is a manual step before the drop. Preloading is required by the same PR. DROP OWNED BY is covered in t/008.