feat(model): res position unique index;

- Create a unique index for active resource positions.

Author: JVickery-TBS

changes/9251.feature

@@ -0,0 +1 @@
+Resource positions are now unique based on a `package_id,position` deferring unique constraint `con_package_resource_unique_position` on the resource table.

ckan/migration/versions/109_e12e991f586b_create_res_position_constraint.py

@@ -0,0 +1,35 @@
+"""Create con_package_resource_unique_position constraint
+to make resource positions unique per package.
+
+Revision ID: e12e991f586b
+Revises: f7b64c701a10
+Create Date: 2026-02-10 18:26:31.122945
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'e12e991f586b'
+down_revision = 'f7b64c701a10'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_unique_constraint(
+        constraint_name='con_package_resource_unique_position',
+        table_name='resource', columns=['package_id', 'position'],
+        deferrable=True, initially="DEFERRED")
+    print('Created "con_package_resource_unique_position"' \
+          ' constraint on resource table')
+
+
+def downgrade():
+    op.drop_constraint(
+        constraint_name='con_package_resource_unique_position',
+        table_name='resource',
+        type_='unique')
+    print('Dropped "con_package_resource_unique_position"' \
+          ' constraint from resource table')

ckan/migration/versions/109_e12e991f586b_create_res_position_index.py

@@ -9,7 +9,7 @@
 from sqlalchemy.ext.orderinglist import ordering_list
 from sqlalchemy import orm
 from ckan.common import config
-from sqlalchemy import types, Column, Table, ForeignKey, Index
+from sqlalchemy import types, Column, Table, ForeignKey, Index, UniqueConstraint
 from typing_extensions import Self
 
 import ckan.model.meta as meta
@@ -59,9 +59,9 @@
     Index('idx_package_resource_id', 'id'),
     Index('idx_package_resource_package_id', 'package_id'),
     Index('idx_package_resource_url', 'url'),
-    Index('idx_package_resource_unique_position',
-          Column('package_id'), Column('position'),
-          unique=True, postgresql_where="(state = 'active'::text)")
+    UniqueConstraint(Column('package_id'), Column('position'),
+        name='con_package_resource_unique_position',
+        deferrable=True, initially='deferred')
 )
 
 

ckan/model/resource.py

@@ -77,4 +77,4 @@ def test_resource_unique_positions(self):
             model.Session.commit()
 
         err = e.value
-        assert 'duplicate key value violates unique constraint "idx_package_resource_unique_position"' in str(err)
+        assert 'duplicate key value violates unique constraint "con_package_resource_unique_position"' in str(err)