Are segments stores on heap or off heap?

Elastic Stack Elasticsearch
1

Here it says off-heap: https://www.elastic.co/guide/en/elasticsearch/guide/master/heap-sizing.html

But the stats for this particular shard in my index...

"segments" : {
"count" : 62,
"memory" : "458.7mb",
"memory_in_bytes" : 481075996,
"index_writer_memory" : "0b",
"index_writer_memory_in_bytes" : 0,
"index_writer_max_memory" : "500kb",
"index_writer_max_memory_in_bytes" : 512000,
"version_map_memory" : "0b",
"version_map_memory_in_bytes" : 0,
"fixed_bit_set" : "0b",
"fixed_bit_set_memory_in_bytes" : 0
},

Is that 458.7mb in on heap memory?

2

Segments need to store some data into memory in order to be searchable efficiently. This number returns the number of bytes that are used for that purpose. A value of -1 indicates that Elasticsearch was not able to compute this number.

https://www.elastic.co/guide/en/elasticsearch/reference/1.5/indices-segments.html