ApsaraDB RDS:Introduction to the check report of a major engine version upgrade for an ApsaraDB RDS for PostgreSQL instance

Warning format: Total disk space: {*} GB; Used disk: {*} GB; Used inodes: {*}; bytes-per-nodes: {*}; Minimum disk space required for upgrade: {*} GB.

Possible cause: Too many objects require sufficient disk space.

Solution:

• In blue-green deployment mode, you must specify a storage capacity for the new RDS instance that is greater than or equal to the minimum disk size required for an upgrade.

• In local upgrade mode, you must expand the storage capacity of the RDS instance that you want to upgrade before the upgrade. The new storage capacity must be greater than or equal to the minimum disk size required for an upgrade. For more information, see Change the configuration.

Warning format: Current memory: {*} GB; Recommended memory: {*} GB; Minimum memory: {*} GB.

Possible cause: Too many objects require sufficient memory to minimize the read-only time of the instance during the upgrade.

Solution:

• For blue-green deployments, when you configure upgrade parameters, the memory in the new instance specification must be greater than or equal to the minimum memory requirement.

• In local upgrade mode, you must upgrade the specifications of the RDS instance if the memory capacity provided by the instance type is less than the recommended memory capacity. For more information, see Change the configuration.

Warning format: The instance has replication slot subscribers. To prevent subscription data inconsistency, see the Alibaba Cloud documentation.

Possible cause: The instance has replication slot subscribers. You can check by executing select * from pg_subscription;.

Solution: See Upgrade the database major version for handling.

Warning format: Total Sequence tables: {0}. Too many Sequence tables will extend the switchover time for logical replication major version upgrade.

Possible cause: The instance contains Sequence tables. You can view all Sequence tables in the database by executing select * from pg_sequences; .

Solution: If there are too many Sequence tables, we recommend that you clone the instance to test the switchover time to ensure it meets your requirements.

Error format: Invalid superuser account: {*}; Invalid account: {*}; Please see the Alibaba Cloud documentation.

Possible cause: There are redundant superuser accounts or abnormal standard accounts.

Solution:

• For redundant superuser accounts, submit a ticket to contact after-sales service for deletion.

• Reset the passwords of the abnormal standard accounts.

Error format: pg_upgrade pre-check task failed, need to check [pg_upgrade error log] and [pg_upgrade-related files and errors].

Possible cause: Pre-check failed.

Solution: Please refer to pg_upgrade error log to resolve the log issues.

Error format: The pg_crypto extension is installed in schema: pg_catalog in database: {*}, please see the Alibaba Cloud documentation.

Possible cause: Because pgcrypto creates functions in pg_catalog that only exist in higher versions, it causes the major version upgrade to fail.

Solution: Delete the pgcrypto extension in each database, and then create the extension in a non-pg_catalog schema.

Error format: Zero-downtime major version upgrade requires minimum minor version 20250228.

Possible cause: The instance's minor engine version is too low.

Solution: Upgrade the minor engine version.

Error format: Foreign tables in database: {0}. Total databases: {1}.

Possible cause: Foreign tables exist.

Solution: Delete the foreign tables.

1. Execute the following SQL statement in each database of the instance to obtain information about foreign tables.

   SELECT COUNT(*) AS count, relkind
   FROM pg_class WHERE relkind IN ('f') GROUP BY relkind;

2. Execute the following SQL statement to delete foreign tables.

   DROP FOREIGN TABLE [ IF EXISTS ] name [ CASCADE | RESTRICT ];

For more information, see Community documentation.

Error format: Tables without primary key or unique key in database: {0}. Total databases: {1}.

Possible cause: Tables without primary keys or unique keys exist.

Solution: Add primary keys or unique keys to the tables.

1. Execute the following SQL statement in each database of the instance to obtain information about tables without primary keys or unique keys.

    SELECT COUNT(*) AS count
   FROM information_schema.tables t
   LEFT JOIN information_schema.table_constraints tc
       ON t.table_name = tc.table_name 
       AND t.table_schema = tc.table_schema
       AND (tc.constraint_type = 'PRIMARY KEY' OR tc.constraint_type = 'UNIQUE')
   JOIN pg_class c 
       ON t.table_name = c.relname
   JOIN pg_namespace ns 
       ON c.relnamespace = ns.oid 
       AND ns.nspname = t.table_schema
   WHERE t.table_type = 'BASE TABLE'
       AND tc.constraint_type IS NULL
       AND t.table_schema NOT IN ('pg_catalog', 'information_schema')
       AND c.relreplident != 'f';

2. Execute the following SQL statement to set the REPLICA IDENTITY of the target table to FULL.

   ALTER TABLE name REPLICA IDENTITY FULL;

3. Execute the following SQL statement to add a primary key or unique key to the target table.

   --Primary key constraint
   ALTER TABLE name
       ADD CONSTRAINT constrain_name PRIMARY KEY (column_name);
   --Unique key constraint
   ALTER TABLE name
       ADD CONSTRAINT constrain_name UNIQUE (column_name);

For more information, see Community documentation.

Error format: Materialized views in database: {0}. Total databases: {1}.

Possible cause: Materialized views exist.

Solution: Delete the materialized views.

1. Execute the following SQL statement in each database of the instance to obtain materialized views.

   SELECT COUNT(*) AS count, relkind
   FROM pg_class
   WHERE relkind IN ('m')
   GROUP BY relkind;

2. Execute the following SQL statement to delete materialized views.

   DROP MATERIALIZED VIEW IF EXISTS name;

Error format: Large objects in database: {0}. Total databases: {1}.

Possible cause: Large objects exist.

Solution: Delete the large objects.

1. Execute the following SQL statement in each database of the instance to obtain large objects.

   SELECT COUNT(*) AS count
   FROM pg_largeobject_metadata;

2. Execute the following SQL statement to delete large objects.

   SELECT lo_unlink(largeobject_oid);

Error format: Logical replication prohibited extensions in database: {0}. Total databases: {1}.

Possible cause: The following four prohibited extensions are used: 'pg_partman', 'pg_cron', 'pg_active', and 'pg_logical'.

Solution: Temporarily delete incompatible extensions.

1. Execute the following SQL statement in each database of the instance to check whether incompatible extensions are installed.

   SELECT COUNT(*) AS count
   FROM pg_extension 
   WHERE extname IN ('pg_partman', 'pg_cron', 'pg_active', 'pglogical');

2. Temporarily delete incompatible extensions.

   DROP EXTENSION extension_name;

Error format: Logical replication requires wal_level to be logical, max_wal_sender and max_replication_slots to be at least {0}, instance wal_level is: {1}, max_wal_sender is: {2}, max_replication_slots is: {3}.

Possible cause: The values of the three parameters do not meet the requirements.

Solution: Modify the parameter values. Note that you may need to restart the instance for the changes to take effect. For more information, see Set the parameters of an instance.