Indexing Buffer

The indexing buffer is used to store newly indexed documents. When it fills up, the documents in the buffer are written to a segment on disk. It is divided between all shards on the node.

The following settings are static and must be configured on every data node in the cluster:

indices.memory.index_buffer_size
Accepts either a percentage or a byte size value. It defaults to 10%, meaning that 10% of the total heap allocated to a node will be used as the indexing buffer size.
indices.memory.min_index_buffer_size
If the index_buffer_size is specified as a percentage, then this setting can be used to specify an absolute minimum. Defaults to 48mb.
indices.memory.max_index_buffer_size
If the index_buffer_size is specified as a percentage, then this setting can be used to specify an absolute maximum. Defaults to unbounded.
indices.memory.min_shard_index_buffer_size
Sets a hard lower limit for the memory allocated per shard for its own indexing buffer. Defaults to 4mb.