lo_compat_privileges

lo_compat_privileges — Enables backward compatibility mode for privilege checks on large objects. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.

Note

Fact — official short description: “Enables backward compatibility mode for privilege checks on large objects.”

Identity

Type , Valuebool: Upstream pg_settings type
Context , Valuesuperuser: Settable at runtime by a superuser
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueVersion and Platform Compatibility / Previous PostgreSQL Versions: Upstream classification
Latest boot value , Valueoff: off

Lifecycle

Fact	Value
First observed	PG9.0 (research boundary)
Present in	PG9.0–19 Beta 3
Removed in	No
Introduction commit	Not asserted: predates the PG9.0 research boundary
Commit date	—
Discussion	—

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG9.0–19 Beta 3	`off`	—	off

How it works

Enables backward compatibility mode for privilege checks on large objects. A superuser or a role granted SET privilege can change it for the relevant session or configuration scope.

The compatibility mode restores pre-9.0 large-object privilege behavior for old applications. It weakens normal ownership/ACL enforcement around large objects and should be a temporary bridge while explicit GRANTs and ownership are corrected.

Monitor and change lo_compat_privileges together with default_with_oids, operator_precedence_warning, synchronize_seqscans. Validate on the relevant server role and real workload, then use its superuser context to choose session change, reload, or restart; a historical boot default is not the current effective value.

Tuning advice

Tip

Advice. These are workload-specific starting points and must be validated with measurements.

Workload	Guidance
OLTP	Keep the modern default and repair legacy clients/SQL that depend on lo_compat_privileges. Test migration at session scope first; do not make a compatibility switch permanent cluster policy.
OLAP	Regression-test ETL, generated SQL, and old drivers, where parsing/quoting assumptions hide. Performance is rarely a reason to change this switch.
Small nodes	Keep the default without a legacy requirement. If temporarily enabled, record owner, affected connections, and a removal date.

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG19 Beta 3; this does not assert current Pigsty support for that historical or beta release.

Template	Effective value	Versus upstream boot	Source expression
OLTP	Unmodified	—	—
OLAP	Unmodified	—	—
CRIT	Unmodified	—	—
TINY	Unmodified	—	—

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.0–19 Beta 3 unmodified; OLAP: PG9.0–19 Beta 3 unmodified; CRIT: PG9.0–19 Beta 3 unmodified; TINY: PG9.0–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Keeping a compatibility switch permanently instead of fixing the client.
Testing in one session and deploying globally to unrelated applications.
Confusing parsing compatibility with data or security compatibility.
Forgetting to remove an override after the upgrade migration is complete.

default_with_oids · operator_precedence_warning · synchronize_seqscans · standard_conforming_strings · array_nulls · backslash_quote