Modify ApsaraDB RDS for PostgreSQL instance parameters - ApsaraDB RDS

Usage notes

Modifying certain parameters requires an instance restart after you click Apply Changes. Check the Force Restart column on the Editable Parameters tab in the console. Restarting interrupts service. Plan accordingly.
When modifying a parameter, check the Valid Values column on the Editable Parameters tab.
Changes to these parameters on a primary instance automatically sync to read-only instances.

wal_level, max_replication_slots, max_wal_senders, max_locks_per_transaction, max_worker_processes, max_prepared_transactions
After you submit a change, the system validates it. If the value is invalid or prevents startup, the change rolls back with a Failed status. Check the Status column on the Edit History tab.
The log_statement parameter cannot be modified directly. Instead, enable or disable SQL Explorer and Audit.

Modify parameter values

Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the instance ID.
In the navigation pane on the left, click Parameters.
On the Editable Parameters tab, find the parameter to modify. Modify parameters individually or in batches:
- Modify a single parameter
  1. Click the icon next to the target parameter.
  2. Enter the new value and click OK.
  3. Click Apply Changes.
  4. Select when the change takes effect: Take Effect Immediately, Take Effect Within the Maintenance Window, or Take Effect at Specified Time Range. Then, click OK.
- Modify parameters in batches
  1. Click Export Parameters to download the parameter file.
  2. Open the file and modify parameter values.
  3. Click Import Parameters.
  4. In the Import Parameters dialog box, paste the modified parameters and values, and click OK.
  5. Verify the changes and click Apply Changes.
  6. Select when the changes take effect: Take Effect Immediately, Take Effect Within the Maintenance Window, or Take Effect at Specified Time Range. Then, click OK.
Note
On the Scheduled Tasks for Parameter Modification tab, view scheduled parameter modifications for Take Effect Within the Maintenance Window or Take Effect at Specified Time Range.

View modification history

Log on to the ApsaraDB RDS console and go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the instance ID.
In the navigation pane on the left, click Parameters.
Click the Edit History tab.
Select a time range and click OK.

Parameter expressions

Use expressions for parameters that depend on instance specifications. When you change the instance type, expression-based parameters adjust automatically.

The following table lists the expression syntax.

Category	Description	Example
Parameters	The following parameters support expressions: Parameters that support expressions work_mem: memory for internal sort operations and hash tables before writing to temporary files. maintenance_work_mem: maximum memory for maintenance operations such as VACUUM and CREATE INDEX. autovacuum_work_mem: maximum memory per autovacuum worker process. max_parallel_workers: maximum workers for parallel operations. max_parallel_workers_per_gather: maximum workers per Gather or Gather Merge node. effective_cache_size: estimated total disk cache size for the query planner. autovacuum_max_workers: maximum concurrent autovacuum processes (excluding the launcher). max_wal_size: WAL size that triggers a checkpoint. min_wal_size: minimum WAL size. Below this threshold, old WAL files are recycled at checkpoints instead of removed. temp_file_limit: maximum disk space per process for temporary files (sorting, hashing, cursors). wal_buffers: shared memory for WAL data not yet written to disk. max_parallel_maintenance_workers: maximum parallel workers for CREATE INDEX. max_worker_processes: maximum concurrent worker processes. Note The max_parallel_maintenance_workers parameter is available only in ApsaraDB RDS for PostgreSQL 11.0 and later.	effective_cache_size
Variables	AllocatedStorage: storage capacity in MB. Integer. DBInstanceClassMemory: memory size in bytes. Integer. DBInstanceClassCPU: number of CPU cores. Integer. DBInstanceClassConnections: maximum connections. Integer. Note For specifications such as storage, memory, CPU cores, and connection limits, see Primary ApsaraDB RDS for PostgreSQL instance types.	effective_cache_size={DBInstanceClassMemory/16384}
Operators	Expression syntax: Expressions must be enclosed in braces (`{}`). Division operator (/): returns an integer quotient. Fractional results are truncated, not rounded. Multiplication operator (*): returns an integer product. Fractional results are truncated, not rounded.	effective_cache_size={DBInstanceClassMemory/16384}
Functions	GREATEST(): returns the largest value from a list of integers or expressions. LEAST(): returns the smallest value from a list of integers or expressions. SUM(): adds values of specified integers or expressions.	max_parallel_workers={GREATEST(DBInstanceClassCPU*3/4, 8)}

References

For PostgreSQL parameter details, see Server Configuration in the PostgreSQL documentation.

To modify parameters by calling API operations:

API	Description
ModifyParameter	Modifies the parameters of an RDS instance.
DescribeParameterTemplates	Queries the parameter template of a database.
DescribeParameters	Queries the current parameters of an instance.

FAQ

Q: How do I increase the maximum connections for an ApsaraDB RDS for PostgreSQL instance?

A: The maximum connections (max_connections) depends on the instance type and cannot be modified directly. To increase connections, upgrade the instance type. For connection limits by instance type, see Primary ApsaraDB RDS for PostgreSQL instance types and Read-only ApsaraDB RDS for PostgreSQL instance types.