# DB cluster parameters in Aurora PostgreSQL Limitless Database
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You can use the following DB cluster parameters to configure Aurora PostgreSQL Limitless Database.

**rds\$1aurora.limitless\$1adaptive\$1fetch\$1size**  
Enhances batch prefetching. When set to `true`, this parameter allows a self-adjusting (adaptive) fetch size for prefetching. When set to `false`, the fetch size is constant.

**rds\$1aurora.limitless\$1auto\$1scale\$1options**  
Sets the options available for adding routers or splitting shards in a DB shard group. The value can be `add_router`, `split_shard`, or both.  
For more information, see [Adding a router to a DB shard group](limitless-add-router.md) and [Splitting a shard in a DB shard group](limitless-shard-split.md).

**rds\$1aurora.limitless\$1distributed\$1deadlock\$1timeout**  
The amount of time to wait on a lock before checking whether there is a distributed deadlock condition, in milliseconds. The default is `1000` (1 second).  
For more information, see [Distributed deadlocks in Aurora PostgreSQL Limitless Database](limitless-query.deadlocks.md).

**rds\$1aurora.limitless\$1enable\$1auto\$1scale**  
Enables the adding of routers and splitting of shards in a DB shard group.  
For more information, see [Adding a router to a DB shard group](limitless-add-router.md) and [Splitting a shard in a DB shard group](limitless-shard-split.md).

**rds\$1aurora.limitless\$1finalize\$1split\$1shard\$1mode**  
Determines how system-initiated shard splits are finalized. For more information, see [Splitting a shard in a DB shard group](limitless-shard-split.md).

**rds\$1aurora.limitless\$1maximum\$1adaptive\$1fetch\$1size**  
Sets the upper limit for the adaptive fetch size. The range is `1`–`INT_MAX`. The default is `1000`.