[[release-notes-7.9.0]]
== {es} version 7.9.0

Also see <<breaking-changes-7.9,Breaking changes in 7.9>>.

[[breaking-7.9.0]]
[float]
=== Breaking changes

Script Cache::
* Script cache size and rate limiting are per-context {es-pull}55753[#55753] (issue: {es-issue}50152[#50152])

Field capabilities API::
* Constant_keyword fields are now described by their family type `keyword` instead of `constant_keyword` {es-pull}58483[#58483] (issue: {es-issue}53175[#53175])

Snapshot restore throttling::
* Restoring from a snapshot (which is a particular form of recovery) is now
  properly taking recovery throttling into account (i.e. the
  `indices.recovery.max_bytes_per_sec` setting).
  The `max_restore_bytes_per_sec` setting is also now defaulting to
  unlimited, whereas previously it was set to `40mb`, which is the
  default that's used for `indices.recovery.max_bytes_per_sec`. This means
  that no behavioral change will be observed by clusters where the recovery
  and restore settings had not been adapted from the defaults. {es-pull}58658[#58658]

Thread pool write queue size::
* The WRITE thread pool default queue size (`thread_pool.write.size`) has been
  increased from 200 to 10000. A small queue size (200) caused issues when users
  wanted to send small indexing requests with a high client count. Additional
  memory-oriented back pressure has been introduced with the
  `indexing_pressure.memory.limit` setting. This setting configures a limit to
  the number of bytes allowed to be consumed by outstanding indexing requests.
  {es-issue}59263[#59263]