# Common tasks for buffer pools
<a name="db2-managing-buffer-pools"></a>

You can create, alter, or drop buffer pools for an RDS for Db2 database. Creating, altering, or dropping buffer pools requires higher-level `SYSADM` or `SYSCTRL` authority, which isn't available to the master user. Instead, use Amazon RDS stored procedures.

You can also flush buffer pools.

**Topics**
+ [Creating a buffer pool](#db2-creating-buffer-pool)
+ [Altering a buffer pool](#db2-altering-buffer-pool)
+ [Dropping a buffer pool](#db2-dropping-buffer-pool)
+ [Flushing the buffer pools](#db2-flushing-buffer-pools)

## Creating a buffer pool
<a name="db2-creating-buffer-pool"></a>

To create a buffer pool for your RDS for Db2 database, call the `rdsadmin.create_bufferpool` stored procedure. For more information, see [CREATE BUFFERPOOL statement](https://www.ibm.com/docs/en/db2/11.5?topic=statements-create-bufferpool) in the IBM Db2 documentation.

**To create a buffer pool**

1. Connect to the `rdsadmin` database using the master username and master password for your RDS for Db2 DB instance. In the following example, replace *master\$1username* and *master\$1password* with your own information.

   ```
   db2 "connect to rdsadmin user master_username using master_password"
   ```

1. Create a buffer pool by calling `rdsadmin.create_bufferpool`. For more information, see [rdsadmin.create\$1bufferpool](db2-sp-managing-buffer-pools.md#db2-sp-create-buffer-pool).

   ```
   db2 "call rdsadmin.create_bufferpool(
       'database_name', 
       'buffer_pool_name', 
       buffer_pool_size, 
       'immediate', 
       'automatic', 
       page_size, 
       number_block_pages, 
       block_size)"
   ```

## Altering a buffer pool
<a name="db2-altering-buffer-pool"></a>

To alter a buffer pool for your RDS for Db2 database, call the `rdsadmin.alter_bufferpool` stored procedure. For more information, see [ALTER BUFFERPOOL statement](https://www.ibm.com/docs/en/db2/11.5?topic=statements-alter-bufferpool) in the IBM Db2 documentation.

**To alter a buffer pool**

1. Connect to the `rdsadmin` database using the master username and master password for your RDS for Db2 DB instance. In the following example, replace *master\$1username* and *master\$1password* with your own information.

   ```
   db2 "connect to rdsadmin user master_username using master_password"
   ```

1. Alter a buffer pool by calling `rdsadmin.alter_bufferpool`. For more information, see [rdsadmin.alter\$1bufferpool](db2-sp-managing-buffer-pools.md#db2-sp-alter-buffer-pool).

   ```
   db2 "call rdsadmin.alter_bufferpool(
       'database_name', 
       'buffer_pool_name', 
       buffer_pool_size, 
       'immediate', 
       'automatic', 
       change_number_blocks, 
       number_block_pages, 
       block_size)"
   ```

## Dropping a buffer pool
<a name="db2-dropping-buffer-pool"></a>

To drop a buffer pool for your RDS for Db2 database, call the `rdsadmin.drop_bufferpool` stored procedure. For more information, see [Dropping buffer pools](https://www.ibm.com/docs/en/db2/11.5?topic=pools-dropping-buffer) in the IBM Db2 documentation.

**Important**  
Make sure that no tablespaces are assigned to the buffer pool that you want to drop. 

**To drop a buffer pool**

1. Connect to the `rdsadmin` database using the master username and master password for your RDS for Db2 DB instance. In the following example, replace *master\$1username* and *master\$1password* with your own information.

   ```
   db2 "connect to rdsadmin user master_username using master_password"
   ```

1. Drop a buffer pool by calling `rdsadmin.drop_bufferpool`. For more information, see [rdsadmin.drop\$1bufferpool](db2-sp-managing-buffer-pools.md#db2-sp-drop-buffer-pool).

   ```
   db2 "call rdsadmin.drop_bufferpool(
       'database_name', 
       'buffer_pool_name')"
   ```

## Flushing the buffer pools
<a name="db2-flushing-buffer-pools"></a>

You can flush the buffer pools to force a checkpoint so that RDS for Db2 writes pages from memory to storage. 

**Note**  
You don't need to flush the buffer pools. Db2 writes logs synchronously before it commits transactions. The dirty pages might still be in a buffer pool, but Db2 writes them to storage asynchronously. Even if the system shuts down unexpectedly, when you restart the database, Db2 automatically performs crash recovery. During crash recovery, Db2 writes committed changes to the database or rolls back changes for uncommitted transactions. 

**To flush the buffer pools**

1. Connect to your Db2 database using the master username and master password for your RDS for Db2 DB instance. In the following example, replace *rds\$1database\$1alias*, *master\$1username*, and *master\$1password* with your own information.

   ```
   db2 connect to rds_database_alias user master_username using master_password
   ```

1. Flush the buffer pools.

   ```
   db2 flush bufferpools all
   ```