Fix zendesk-5146. Add check for empty columns in unique constraints g…

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4764
GitOrigin-RevId: 79e62f1ea2639ec81a48f5f71b58eaadf4fe6482

CHANGELOG.md

@@ -19,6 +19,7 @@ Event Triggers support has been added for MS SQL Server. Now, you can invoke ext
 - cli: fix perfomance regression with large metadata in `metadata apply`
 - cli: fix error reporting in `metadata apply` command (#8280)
 - server: query runtime performance optimizations
+- server: fix bug that had disabled expression-based indexes in Postgress variants (fix Zendesk 5146)
 
 ## v2.8.0
 

server/src-rsr/citus_table_metadata.sql

@@ -143,7 +143,7 @@ LEFT JOIN LATERAL
           'name', class.relname,
           'oid', class.oid :: integer
           ),
-        'columns', columns.info
+        'columns', coalesce(columns.info, '[]')
         )
       ) AS info
     FROM pg_catalog.pg_index index

server/src-rsr/pg_table_metadata.sql

@@ -136,7 +136,7 @@ LEFT JOIN LATERAL
           'name', class.relname,
           'oid', class.oid :: integer
           ),
-        'columns', columns.info
+        'columns', coalesce(columns.info, '[]')
         )
       ) AS info
     FROM pg_catalog.pg_index idx