.. Licensed under the Apache License, Version 2.0 (the "License"); you may not
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.. _release/3.3.x:

============
3.3.x Branch
============

.. contents::
    :depth: 1
    :local:

.. _release/3.3.0:

Version 3.3.0
=============

Highlights
----------

* :ghissue:`4308`: Replicator was optimized and should be faster. It now uses
  the `_bulk_get` endpoint on the source, and can statistically skip calling
  `_revs_diff` on the target. Benchmark tests replicating 1M documents, 10KB
  each, from UK to US East show a 3x speed improvement.

.. figure:: ../../images/tea-erl-grey-hot-replicator.png
  :align: center
  :alt: Replicator, Tea! Earl Grey! Hot! (Because Picard said so)

Features and Enhancements
-------------------------

* :ghissue:`3766`, :ghissue:`3970`, :ghissue:`3972`, :ghissue:`4093`,
  :ghissue:`4102`, :ghissue:`4104`, :ghissue:`4110`, :ghissue:`4111`,
  :ghissue:`4114`, :ghissue:`4245`, :ghissue:`4246`:, :ghissue:`4266`: Add
  ``smoosh`` queue persistence. This allows resuming ``smoosh`` operations
  after a node restart. This is disabled by default and can be enabled with
  ``[smoosh] persist = true``. Optimise ``smoosh`` operations and increase
  test coverage to 90%.

* :ghissue:`3798`: Add ``libicu`` version and collation algorithm version to
  ``/_node/_local/_versions``.

* :ghissue:`3837`: The Erlang source tree is now auto-formatted with ``erlfmt``.

* :ghissue:`3845`: Clean up the ``couch_ejson_compare`` C-module and squash
  Microsoft compiler warnings.

* :ghissue:`3832`: Add ``GET`` variant to ``_dbs_info`` endpoint, used to be
  ``POST`` only.

* :ghissue:`3864`: Improve ``erlang_ls`` configuration.

* :ghissue:`3853`: Remove legacy ``ddoc_cache_opener`` ``gen_server`` and
  speed up event routing.

* :ghissue:`3879`: Remove use of ``ERL_OPTS`` environment variable. All
  supported Erlang versions now use ``ERL_COMPILER_OPTIONS`` for the same
  purpose.

* :ghissue:`3883`: Add support for SpiderMonkey 91.

* :ghissue:`3889`: Track ``libicu`` collator versions in the view header.

* :ghissue:`3952`: Make the timeout for receiving requests from attachment
  writers configurable.

* :ghissue:`3927`: Include index signature in ``_search_info``.

* :ghissue:`3963`: Optimtize key tree stemming by using maps instead of
  sets. This greatly reduced memory usage for heavily conflicted docs in some
  situations.

* :ghissue:`3974`: Create new config options in ``[couchdb]`` and ``[smoosh]``
  sections to enable finer control of compaction logging levels.

* :ghissue:`3983`, :ghissue:`3984`, :ghissue:`3985`, :ghissue:`3987`,
  :ghissue:`4033`: Add various functions to ``couch_debug`` module.

* :ghissue:`4000`: Ensure ``Object.prototype.toSource()`` is always available.

* :ghissue:`4018`: Update ``jiffy`` to 1.1.1 and ``b64url`` to 1.0.3.

* :ghissue:`4021`: Reduce smoosh compaction log level to ``debug``.

* :ghissue:`4041`: Allow and evaluate nested json claim roles in JWT token.

* :ghissue:`4060`, :ghissue:`4290`: Add support for Erlang 25.

* :ghissue:`4064`: Enable replicating purge requests between nodes. Also avoid
  applying interactive purges more than once.

* :ghissue:`4069`, :ghissue:`4084`: Drop support for Erlang < 23, update
  ``vm.args`` settings to match. Review this if you have customized your
  ``vm.args``.

* :ghissue:`4083`: Support Elixir 13.

* :ghissue:`4085`: Add an option to let ``custodian`` always use ``[cluster] n``
  value.

* :ghissue:`4095`: Implement ``winning_revs_only`` option for the replicator. It
  replicates only the winning revisions from the source to the target,
  effectively discarding conflicts.

* :ghissue:`4135`: Separate search IO from file IO.

* :ghissue:`4140`, :ghissue:`4162`: Upgrade hash algorithm for cookie auth (sha1
  -> sha256). This introduces a new config setting ``hash_algorithms``. New cookie
  values are hashed with sha256, sha1 hashes are still accepted. Admins can set
  this to sha256 only. Sha1 will be disallowed in the next major release. Show
  supported hash algorithms in ``/_node/_local/_versions`` endpoint.

* :ghissue:`4179`: Don't double-encode changes sequence strings in the
  replicator.

* :ghissue:`4182`: Explicitly maintain a fully connected cluster. Previously, it
  was possible for the nodes to disconnect, and for that state to persist until
  the nodes restarted.

* :ghissue:`4198`: Redact passwords in log file.

* :ghissue:`4243`: Update ``mochiweb`` to 3.1.1.

* :ghissue:`4254`: The ``_dbs_info`` access control is now configured with the
  ``[couchdb] admin_only_all_dbs`` setting. Defaults to true. This was a
  leftover from the 3.0.0 release.

* :ghissue:`4264`: ``active`` database sizes is now limited to leaf nodes.
  Previously, it included intermediate tree nodes, which had the effect that
  deleting (large) documents did not decrease ``active`` database size. In
  addition, ``smoosh`` now picks up databases where large documents are
  deleted for compaction more eagerly, reclaiming the deleted space quicker.

* :ghissue:`4270`: Shard splitting now uses its own ``reshard`` IO priority.
  It can be configured to be safely run in the background with production
  loads, or with maximum IO available, if admins prefer quicker progress.

* :ghissue:`4274`: Improve validation of replicator job parameters & move
  ``_replicator`` VDU design doc to internal BDU.

* :ghissue:`4280`: Add ``CFLAGS`` and ``LDFLAGS`` to ICU build parameters.

* :ghissue:`4284`: Remove all usage of global to avoid potential deadlocks
  in replication jobs.

* :ghissue:`4287`: Allow ``=`` in config key names.

* :ghissue:`4306`: Fauxton was updated to version v1.2.9. Changes since v1.2.8
  can be found `here
  <https://github.com/apache/couchdb-fauxton/releases/tag/v1.2.9>`_

* :ghissue:`4317`: Write "Relax" welcome message to standard out on
  Windows.

Performance
-----------

* :ghissue:`3860`: Add sharding to ``couch_index_server``, similar to
  :ghissue:`3366`, avoids processing bottlenecks on servers with a lot of
  concurrent view indexing going on.

* :ghissue:`3891`: Avoid decoding JWT payloads when not necessary.

* :ghissue:`4031`: Default ``[rexi] use_kill_all`` to ``true``. This improves
  intra-cluster-node messaging. Set to false if you run a cluster with nodes
  that have a version <3.0.0.

* :ghissue:`4052`: Optimise ``couch_util:reorder_results/2,3``, which speeds up
  ``_bulk_docs`` and ``_revs_diff``.

* :ghissue:`4055`: Avoid using ``length/1`` guard for ``>0`` or ``==0`` tests in
  ``couch_key_tree``.

* :ghissue:`4056`: Optimise ``couch_key_tree:find_missing/2``. This speeds up
  ``_revs_diff``.

* :ghissue:`4059`: Reduce complexity of ``possible_ancestors`` from quadratic to
  linear. This speeds up working with heavily conflicted documents
  significantly.

* :ghissue:`4091`: Optimise ``couch_util:to_hex/1``, this speeds up all
  operations that need to encode a revision id into JSON (this is most
  operations).

* :ghissue:`4106`: Set ``io_priority`` in all IO paths. Introduces ``system``
  ``io_priority``.

* :ghissue:`4144`, :ghissue:`4172`: Implement ``_bulk_get`` support for the
  replicator. Backward compatibility is ensured. This speeds up all
  replications. Add option to disable new behaviour for legacy setups.

* :ghissue:`4163`: Statistically skip ``_revs_diff`` in the replicator. This
  improves performance for replications into empty targets.

* :ghissue:`4177`: Remove the long deprecated ``bigcouch 0.4`` change sequence
  support.

* :ghissue:`4238`: Optimise ``_bulk_get`` endpoint. This speeds up replication
  of 1M docs by ~2x. Individual ``_bulk_get`` requests are up to 8x faster.

* :ghissue:`3517`: Add experimental fix for reduce performance regression due
  to expensive repeated AST-transformations on newer SpiderMonkey versions.
  Set ``COUCHDB_QUERY_SERVER_JAVASCRIPT`` env var to
  ``COUCHDB_QUERY_SERVER_JAVASCRIPT="/opt/couchdb/bin/couchjs
  /opt/couchdb/share/server/main-ast-bypass.js"``.

* :ghissue:`4262`: ``couchjs`` executable built against Spidermonkey >= 78 will
  return the detailed ``major.minor.patch`` as opposed to just the ``major``
  version as previously.

Bugfixes
--------

* :ghissue:`3817`: Fix undefined function call in ``weatherreport``.

* :ghissue:`3819`: Return ``400`` instead of ``500`` response code for known
  invalid ``_bulk_docs`` with ``new_edits=false`` request.

* :ghissue:`3861`: Add ``SameSite`` setting when clearing session cookies.

* :ghissue:`3863`: Fix custom TLS distribution for Erlang 20.

* :ghissue:`3870`: Always send all cookie attributes.

* :ghissue:`3886`: Avoid changes feed rewind after shard move with no subsequent
  db updates.

* :ghissue:`3888`: Make ``_stats`` endpoint resilient against nodes that go
  offline.

* :ghissue:`3901`: Use db-creation time instead of ``0`` for
  ``instance_start_time`` to help replicator recognise whether a peer database
  was deleted and recreated.

* :ghissue:`3909`: Fix ``new_edits:false`` and VDU ``function_clause``.

* :ghissue:`3934`: Fix ``replicated_changes`` typo for purge doc updates.

* :ghissue:`3940`: Ensure the multipart parser always monitors the worker and
  make sure to wait for attachment uploads before responding.

* :ghissue:`3950`: Ignore responses from timed-out or retried ``ibrowse`` calls.

* :ghissue:`3969`: Fix ``skip`` and ``limit`` for ``_all_dbs`` and
  ``_dbs_info``.

* :ghissue:`3979`: Correctly respond with a ``500`` code when document updates
  time out under heavy load.

* :ghissue:`3992`: Show that Search is available if it was available
  before. Avoid Search availability disappearing just because a Search node was
  temporarily not available.

* :ghissue:`3993`: Return a ``400`` error when decoding a JWT token fails,
  rather than crashing and not responding at all.

* :ghissue:`3990`: Prevent creation of ddocs with no name through Mango index
  creation.

* :ghissue:`4003`: Improve index building during shard splitting.

* :ghissue:`4016`: Fix ``function_clause`` error for replicated changes with a
  target VDU.

* :ghissue:`4020`: Fix ``maybe_handle_error`` clauses.

* :ghissue:`4037`: Fix ES{256,384,512} support for JWTs.

* :ghissue:`4040`: Handle ``exit(shutdown)`` error in ``chttpd``.

* :ghissue:`4043`: Fix purge request timeouts (5s -> infinity).

* :ghissue:`4146`: The ``devcontainer`` has been updated.

* :ghissue:`4050`: Handle ``all_dbs_active`` in ``fabric_doc_update``.

* :ghissue:`4160`: Return a proper ``400`` error when an invalid object is sent
  to ``_bulk_get``.

* :ghissue:`4070`: Prevent ``error:function_clause`` in ``check_security/3`` if
  roles claim is malformed.

* :ghissue:`4075`: Fix ``couch_debug:opened_files*`` functions.

* :ghissue:`4108`: Trim ``X-Auth-CouchDB-Roles`` header after reading.

* :ghissue:`4153`: The ``require_valid_user`` setting is now under ``chttpd``.

* :ghissue:`4161`: Fix ``content-type`` handling in ``_session``.

* :ghissue:`4176`: Fix ``eventsource`` ``_changes`` feed.

* :ghissue:`4197`: Support large (and impractical as-of-yet) ``q`` values. Fix
  shard open timeouts for ``q > 64``.

* :ghissue:`4199`: Fix spurious unlock in ``close_db_if_idle``.

* :ghissue:`4230`: Avoid refresh messages piling up in prometheus server.

* :ghissue:`4240`: Implement global password hasher process. This fixes a
  race-condition when setting new admin passwords in quick succession on a
  multicore server.

* :ghissue:`4261`, :ghissue:`4271`: Clean up stale view checkpoints,
  improve purge client cleanup logging

* :ghissue:`4272`: Kill all ``couch_server_N`` if ``database_dir`` changes.

* :ghissue:`4313`: Use ``chttpd`` config section when patching local
  ``_replicate`` endpoints.

* :ghissue:`4321`: Downgrade jiffy to allow building on Windows again.

* :ghissue:`4329`, :ghissue:`4323`: Ignore build windows binaries in
  git.

Tests
-----

* :ghissue:`3825`: Eliminate Elixir compiler warnings.

* :ghissue:`3830`: Reduce skipped Elixir integration tests.

* :ghissue:`3890`: Handle ``not_found`` lookups removing ddoc cache key.

* :ghissue:`3892`: Use Debian Stable for CI, add Erlang 24 to CI.

* :ghissue:`3898`: Remove CI support for Ubuntu 16.04.

* :ghissue:`3903`, :ghissue:`3914`: Refactor Jenkins to dynamically generate
  stages. Drop ``MINIMUM_ERLANG_VERSION`` to 20, drop the packaging
  ``ERLANG_VERSION`` to 23, add the ``weatherreport-test`` as a build step, and
  add ``ARM`` and ``POWER`` back into the matrix.

* :ghissue:`3921`:, :ghissue:`3923`: Execute various tests in clean
  ``database_dir`` to avoid subsequent test flakiness.

* :ghissue:`3968`: Ensure key tree rev stemming does’t take too much memory.

* :ghissue:`3980`: Upgrade Mango test dependency ``nose`` to ``nose`` and fix
  flaky-on-Windows tests.

* :ghissue:`4006`: Remove CI support for Debian 9.

* :ghissue:`4061`, :ghissue:`4082`: Update PPC CI builder.

* :ghissue:`4096`: Fix flaky ``validate_doc_update`` Elixir test.

* :ghissue:`4123`: Fix ``haproxy.cfg``.

* :ghissue:`4126`: Return a ``400`` response for a single ``new_edits=false``
  doc update without revision.

* :ghissue:`4129`: Fix ``proxyauth_test`` and removed it from skip list.

* :ghissue:`4132`: Address race condition in ``cpse_incref_decref`` test.

* :ghissue:`4151`: Refactor replication tests to use clustered endpoints.

* :ghissue:`4178`: Add test coverage to prevent junk in ``eventsource``.

* :ghissue:`4188`: Enable eunit coverage for all applications instead of
  enabling it per-application.

* :ghissue:`4202`: Fix race condition in ddoc cache LRU test.

* :ghissue:`4203`, :ghissue:`4205`: Reduce test log noise.

* :ghissue:`4268`: Improve flaky ``_dbs_info`` test.

* :ghissue:`4319`: Fix offline ``configure`` and ``make release``.

* :ghissue:`4328`: Fix ``eaddrnotavail`` in Elixir tests under Windows.

* :ghissue:`4330`: Do not run source checks in main CI build.

Docs
----

* :ghissue:`4164`: The CouchDB documentation has been moved into the main
  CouchDB repository.

* :ghissue:`4307`, :ghissue:`4174`: Update Sphinx to version 5.3.0

* :ghissue:`4170`: Document the ``/_node/_local/_versions`` endpoint.

Builds
------

* :ghissue:`4097`: Stop publication of nightly packages. They were not used
  anywhere.

* :ghissue:`4322`: Reuse installed rebar and rebar3
  for mix. Compatible with Elixir =< 13 only. Elixir 14 is not
  supported yet.

* :ghissue:`4326`: Move Elixir source checks to a separate build step.

Other
-----

* Added pumpkin spice to selected endpoints. — Thank you for reading the 3.3.0
  release notes.