Add pg_upgrade support functions #2326

jrgemignani · 2026-02-02T19:31:29Z

Add pg_upgrade support functions for PostgreSQL major version upgrades

NOTE: This PR was created with AI tools and a human.

The ag_graph.namespace column uses the regnamespace type, which pg_upgrade cannot handle in user tables. This commit adds four SQL functions to enable seamless PostgreSQL major version upgrades while preserving all graph data.

New functions in ag_catalog:

age_prepare_pg_upgrade(): Converts namespace from regnamespace to oid, creates backup table with graph-to-namespace mappings
age_finish_pg_upgrade(): Remaps stale OIDs after upgrade, restores regnamespace type, invalidates AGE caches
age_revert_pg_upgrade_changes(): Cancels preparation if upgrade is aborted
age_pg_upgrade_status(): Returns current upgrade readiness status

Usage:

Before pg_upgrade: SELECT age_prepare_pg_upgrade();
Run pg_upgrade as normal
After pg_upgrade: SELECT age_finish_pg_upgrade();

The functions include automatic cache invalidation by touching graph namespaces, ensuring cypher queries work immediately without requiring a session reconnect.

Files changed:

sql/age_pg_upgrade.sql: New file with function implementations
sql/sql_files: Added age_pg_upgrade entry
age--1.7.0--y.y.y.sql: Added functions for extension upgrades

All regressions tests passed.

Add pg_upgrade support functions for PostgreSQL major version upgrades NOTE: This PR was created with AI tools and a human. The ag_graph.namespace column uses the regnamespace type, which pg_upgrade cannot handle in user tables. This commit adds four SQL functions to enable seamless PostgreSQL major version upgrades while preserving all graph data. New functions in ag_catalog: - age_prepare_pg_upgrade(): Converts namespace from regnamespace to oid, creates backup table with graph-to-namespace mappings - age_finish_pg_upgrade(): Remaps stale OIDs after upgrade, restores regnamespace type, invalidates AGE caches - age_revert_pg_upgrade_changes(): Cancels preparation if upgrade is aborted - age_pg_upgrade_status(): Returns current upgrade readiness status Usage: 1. Before pg_upgrade: SELECT age_prepare_pg_upgrade(); 2. Run pg_upgrade as normal 3. After pg_upgrade: SELECT age_finish_pg_upgrade(); The functions include automatic cache invalidation by touching graph namespaces, ensuring cypher queries work immediately without requiring a session reconnect. Files changed: - sql/age_pg_upgrade.sql: New file with function implementations - sql/sql_files: Added age_pg_upgrade entry - age--1.7.0--y.y.y.sql: Added functions for extension upgrades All regressions tests passed.

Copilot

Pull request overview

Adds PostgreSQL pg_upgrade helper functions to Apache AGE to work around regnamespace being unsupported by pg_upgrade in user tables, enabling major-version upgrades while preserving graph metadata.

Changes:

Introduces age_prepare_pg_upgrade(), age_finish_pg_upgrade(), age_revert_pg_upgrade_changes(), and age_pg_upgrade_status() in ag_catalog.
Registers the new SQL file in the extension build/install process.
Adds the same functions to the extension upgrade script for 1.7.0 -> y.y.y.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 17 comments.

File	Description
`sql/sql_files`	Adds the new `age_pg_upgrade` SQL script to the extension SQL composition list.
`sql/age_pg_upgrade.sql`	Implements the four pg_upgrade support functions (prepare/finish/revert/status).
`age--1.7.0--y.y.y.sql`	Adds the same functions to the extension upgrade path script.

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Copilot · 2026-02-09T12:01:23Z

age--1.7.0--y.y.y.sql

+    PERFORM pg_catalog.pg_advisory_lock(hashtext('age_finish_pg_upgrade'));
+    BEGIN
+        -- Touch each graph's namespace to invalidate caches
+        DECLARE
+            graph_rec RECORD;
+        BEGIN
+            FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph
+            LOOP
+                EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);
+            END LOOP;
+        END;
+    END;
+    PERFORM pg_catalog.pg_advisory_unlock(hashtext('age_finish_pg_upgrade'));
+


The cache invalidation uses pg_advisory_lock()/pg_advisory_unlock() (session-level). If an error occurs while looping/altering schemas, the unlock won't execute and the session can keep the lock, blocking future calls. Prefer pg_advisory_xact_lock() or wrap the block with EXCEPTION handling that always unlocks.

sql/age_pg_upgrade.sql

Copilot · 2026-02-09T12:01:24Z

age--1.7.0--y.y.y.sql

+        g.namespace::regnamespace::text AS namespace_name
+    FROM ag_catalog.ag_graph g;


The backup stores namespace_name as g.namespace::regnamespace::text, which can include quoted identifiers. age_finish_pg_upgrade() later joins this to pg_namespace.nspname (unquoted), so remapping can fail for schemas that require quoting. Store pg_namespace.nspname instead (e.g., join via namespace::oid) to make the mapping stable.

Suggested change

g.namespace::regnamespace::text AS namespace_name

FROM ag_catalog.ag_graph g;

n.nspname AS namespace_name

FROM ag_catalog.ag_graph g

JOIN pg_namespace n ON n.oid = g.namespace::oid;

Copilot · 2026-02-09T12:01:24Z

age--1.7.0--y.y.y.sql

+    -- Create temporary mapping table with old and new OIDs
+    CREATE TEMP TABLE _graphid_mapping AS
+    SELECT
+        b.old_graphid,
+        b.graph_name,
+        n.oid AS new_graphid
+    FROM public._age_pg_upgrade_backup b
+    JOIN pg_namespace n ON n.nspname = b.namespace_name;
+
+    GET DIAGNOSTICS mapping_count = ROW_COUNT;
+
+    IF mapping_count = 0 THEN
+        RAISE EXCEPTION 'No OID mappings found. Schema names may have changed.';
+    END IF;


The join to pg_namespace uses n.nspname = b.namespace_name, but namespace_name was stored from regnamespace::text (potentially quoted), so this join can fail and drop mappings. Consider normalizing the stored schema name and validating that every backup row has a mapping (e.g., compare mapping_count to backup row count and raise if mismatched).

Copilot · 2026-02-09T12:01:25Z

age--1.7.0--y.y.y.sql

+    -- Clean up temporary mapping table
+    DROP TABLE _graphid_mapping;
+    DROP TABLE public._age_pg_upgrade_backup;
+


age_finish_pg_upgrade() drops public._age_pg_upgrade_backup before the schema restoration + cache invalidation steps run. If a later step fails, the backup is gone and recovery/reruns are harder. Consider dropping the backup only after all steps complete successfully.

Copilot · 2026-02-09T12:01:27Z

age--1.7.0--y.y.y.sql

+    PERFORM pg_catalog.pg_advisory_lock(hashtext('age_revert_pg_upgrade'));
+    BEGIN
+        DECLARE
+            graph_rec RECORD;
+        BEGIN
+            FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph
+            LOOP
+                EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);
+            END LOOP;
+        END;
+    END;
+    PERFORM pg_catalog.pg_advisory_unlock(hashtext('age_revert_pg_upgrade'));
+


age_revert_pg_upgrade_changes() uses session-level advisory locks without exception safety (lock may remain held on error) and alters schema ownership to CURRENT_USER (persistent side effect / possible privilege failure). Prefer xact-level advisory locks and an invalidation method that doesn't leave owners changed (and avoid identifier double-quoting).

Suggested change

PERFORM pg_catalog.pg_advisory_lock(hashtext('age_revert_pg_upgrade'));

BEGIN

DECLARE

graph_rec RECORD;

BEGIN

FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph

LOOP

EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);

END LOOP;

END;

END;

PERFORM pg_catalog.pg_advisory_unlock(hashtext('age_revert_pg_upgrade'));

PERFORM pg_catalog.pg_advisory_xact_lock(hashtext('age_revert_pg_upgrade'));

<<invalidate_caches>>

DECLARE

graph_rec RECORD;

ns_owner text;

BEGIN

FOR graph_rec IN

SELECT namespace::text AS ns_name

FROM ag_catalog.ag_graph

LOOP

SELECT n.nspowner::regrole::text

INTO ns_owner

FROM pg_namespace n

WHERE n.nspname = graph_rec.ns_name;

IF ns_owner IS NOT NULL THEN

EXECUTE format(

'ALTER SCHEMA %s OWNER TO %s',

pg_catalog.quote_ident(graph_rec.ns_name),

pg_catalog.quote_ident(ns_owner)

);

END IF;

END LOOP;

END invalidate_caches;

Copilot · 2026-02-09T12:01:27Z

sql/age_pg_upgrade.sql

+    PERFORM pg_catalog.pg_advisory_lock(hashtext('age_finish_pg_upgrade'));
+    BEGIN
+        -- Touch each graph's namespace to invalidate caches
+        DECLARE
+            graph_rec RECORD;
+        BEGIN
+            FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph
+            LOOP
+                EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);
+            END LOOP;
+        END;
+    END;
+    PERFORM pg_catalog.pg_advisory_unlock(hashtext('age_finish_pg_upgrade'));
+


The cache invalidation uses pg_advisory_lock()/pg_advisory_unlock() (session-level locks). If an error occurs inside the BEGIN block, the unlock won't execute and the session can retain the lock, blocking future runs. Prefer pg_advisory_xact_lock() (auto-released at transaction end) or add an EXCEPTION handler that always unlocks.

Copilot · 2026-02-09T12:01:27Z

sql/age_pg_upgrade.sql

+            FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph
+            LOOP
+                EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);


Using ALTER SCHEMA ... OWNER TO CURRENT_USER as a "touch" is not side-effect free: it can permanently change schema ownership and may fail if CURRENT_USER isn't allowed to change the owner. Also, namespace::text for regnamespace is already quoted, so using format('%I', ns_name) can over-quote and break for schemas needing quotes. Consider fetching pg_namespace.nspname and current owner, then toggling owner and restoring it (or another approach that preserves ownership), and ensure identifiers are quoted exactly once.

Suggested change

FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph

LOOP

EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);

FOR graph_rec IN

SELECT

n.nspname AS ns_name,

r.rolname AS owner_name

FROM ag_catalog.ag_graph g

JOIN pg_catalog.pg_namespace n ON n.oid = g.namespace

JOIN pg_catalog.pg_roles r ON r.oid = n.nspowner

LOOP

-- Temporarily change owner to CURRENT_USER to trigger cache invalidation,

-- then restore the original owner to preserve permissions.

EXECUTE format(

'ALTER SCHEMA %I OWNER TO %I',

graph_rec.ns_name,

current_user

);

EXECUTE format(

'ALTER SCHEMA %I OWNER TO %I',

graph_rec.ns_name,

graph_rec.owner_name

);

Copilot · 2026-02-09T12:01:28Z

age--1.7.0--y.y.y.sql

+DECLARE
+    has_graphs boolean;
+BEGIN
+    -- Check if there are any graphs to process
+    SELECT EXISTS(SELECT 1 FROM ag_catalog.ag_graph) INTO has_graphs;
+
+    IF NOT has_graphs THEN
+        RAISE NOTICE 'No graphs found. Nothing to prepare for pg_upgrade.';
+        RETURN;
+    END IF;
+


age_prepare_pg_upgrade() returns early when there are no rows in ag_catalog.ag_graph, but pg_upgrade compatibility depends on the presence of the regnamespace-typed column, not on row count. Consider still converting ag_graph.namespace to oid (backup can be empty) so pg_upgrade succeeds even with zero graphs.

Suggested change

DECLARE

has_graphs boolean;

BEGIN

-- Check if there are any graphs to process

SELECT EXISTS(SELECT 1 FROM ag_catalog.ag_graph) INTO has_graphs;

IF NOT has_graphs THEN

RAISE NOTICE 'No graphs found. Nothing to prepare for pg_upgrade.';

RETURN;

END IF;

BEGIN

Copilot · 2026-02-09T12:01:28Z

age--1.7.0--y.y.y.sql

+        namespace = m.new_graphid
+    FROM _graphid_mapping m
+    WHERE g.graphid = m.old_graphid;
+


updated_graphs is never set (missing GET DIAGNOSTICS ... = ROW_COUNT after updating ag_graph), so the NOTICE will report NULL and you lose an important verification point. Capture ROW_COUNT after the UPDATE and consider asserting it matches expected mappings.

Suggested change

GET DIAGNOSTICS updated_graphs = ROW_COUNT;

jrgemignani requested a review from MuhammadTahaNaveed February 2, 2026 19:31

jrgemignani closed this Feb 2, 2026

jrgemignani reopened this Feb 2, 2026

github-actions bot added master override-stale To keep issues/PRs untouched from stale action labels Feb 2, 2026

MuhammadTahaNaveed requested a review from Copilot February 9, 2026 11:53

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Add pg_upgrade support functions #2326

Add pg_upgrade support functions #2326

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		g.namespace::regnamespace::text AS namespace_name
		FROM ag_catalog.ag_graph g;

-            FOR graph_rec IN SELECT namespace::text AS ns_name FROM ag_catalog.ag_graph
-            LOOP
-                EXECUTE format('ALTER SCHEMA %I OWNER TO CURRENT_USER', graph_rec.ns_name);
+            FOR graph_rec IN
+                SELECT
+                    n.nspname AS ns_name,
+                    r.rolname AS owner_name
+                FROM ag_catalog.ag_graph g
+                JOIN pg_catalog.pg_namespace n ON n.oid = g.namespace
+                JOIN pg_catalog.pg_roles r ON r.oid = n.nspowner
+            LOOP
+                -- Temporarily change owner to CURRENT_USER to trigger cache invalidation,
+                -- then restore the original owner to preserve permissions.
+                EXECUTE format(
+                    'ALTER SCHEMA %I OWNER TO %I',
+                    graph_rec.ns_name,
+                    current_user
+                );
+                EXECUTE format(
+                    'ALTER SCHEMA %I OWNER TO %I',
+                    graph_rec.ns_name,
+                    graph_rec.owner_name
+                );

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