targetShardCount

The new number of shards. This value has the following default limits. By default, you cannot do the following:

• Set this value to more than double your current shard count for a stream.

• Set this value below half your current shard count for a stream.

• Set this value to more than 10000 shards in a stream (the default limit for shard count per stream is 10000 per account per region), unless you request a limit increase.

• Scale a stream with more than 10000 shards down unless you set this value to less than 10000 shards.