# 1.1. 2.3.x Branch

- Upgrade Notes
- Version 2.3.1
- Version 2.3.0

## 1.1.1. Upgrade Notes

- #1602: To improve security, there have been major changes in the configuration of query servers, SSL support, and HTTP global handlers:

  > 1. Query servers

  > Query servers are NO LONGER DEFINED in the .ini files, and can no longer be altered at run-time.

  > The JavaScript and CoffeeScript query servers continue to be enabled by default. Setup differences have been moved from default.ini to the `couchdb` and `couchdb.cmd` start scripts respectively.

  > Additional query servers can now be configured using environment variables:

  >     export COUCHDB_QUERY_SERVER_PYTHON="/path/to/python/query/server.py with args"
  >     couchdb

  > where the last segment in the environment variable (`_PYTHON`) matches the usual lowercase(!) query language in the design doc `language` field (here, `python`.)

  > Multiple query servers can be configured by using more environment variables.

  > You can also override the default servers if you need to set command- line options (such as `couchjs` stack size):

  >     export COUCHDB_QUERY_SERVER_JAVASCRIPT="/path/to/couchjs /path/to/main.js -S <STACKSIZE>"
  >     couchdb

  > 2. Native Query Servers

  > The mango query server continues to be enabled by default. The Erlang query server continues to be disabled by default. This change adds a `[native_query_servers] enable_erlang_query_server = BOOL` setting (defaults to `false`) to enable the Erlang query server.

  > If the legacy configuration for enabling the query server is detected, that is counted as a `true` setting as well, so existing configurations continue to work just fine.

  > 3. SSL Support

  > Enabling SSL support in the ini file is now easier:

  >     [ssl]
  >     enable = true

  > If the legacy httpsd configuration is found in your ini file, this will still enable SSL support, so existing configurations do not need to be changed.

  > 4. HTTP global handlers

  > These are no longer defined in the default.ini file, but have been moved to the couch.app context. If you need to customize your handlers, you can modify the app context using a couchdb.config file as usual.

- #1602: Also to improve security, the deprecated `os_daemons` and `couch_httpd_proxy` functionality has been completely removed ahead of the planned CouchDB 3.0 release. We recommend the use of OS-level daemons such as runit, sysvinit, systemd, upstart, etc. to launch and maintain OS daemons instead, and the use of a reverse proxy server in front of CouchDB (such as haproxy) to proxy access to other services or domains alongside CouchDB.

- #1543: The node-local (default port 5986) `/_restart` endpoint has been replaced by the clustered (default port 5984) endpoint `/_node/$node/_restart` and `/_node/_local/_restart` endpoints. The node-local endpoint has been removed.

- #1764: All python scripts shipped with CouchDB, including `couchup` and the `dev/run` development cluster script, now specify and require Python 3.x.

- #1396: CouchDB is now compatible with Erlang 21.x.

- #1680: The embedded version of `rebar` used to build CouchDB has been updated to the last version of `rebar2` available. This assists in building on non-x86 platforms.

- #1875: Refuse building with known bad versions of Erlang.

## 1.1.2. Version 2.3.1

### 1.1.2.1. Features

- #1811: Add new `/{db}/_sync_shards` endpoint (admin-only).

- #1870: Update to mochiweb 2.19.0. See also #1875.

- #1875: Refuse building with known bad versions of Erlang.

- #1880: Compaction: Add snooze_period_ms for finer tuning.

### 1.1.2.2. Bugfixes

- #1795: Filter out empty missing_revs results in `mem3_rep`.

- #1384: Fix `function_clause` error on invalid DB `_security` objects.

- #1841: Fix `end_time` field in `/_replicate` response.

- #1860: Fix read repair in a mixed cluster environment.

- #1862: Fix `fabric_open_doc_revs`.

- #1865: Support purge requests with more than 100 doc ids.

- #1867: Fix timeout in `chttpd_purge_tests`.

- #1766: Add default fabric request timeouts.

- #1810: Requests return 400 Bad Request when URL length exceeds 1460 characters. See #1870 for details.

- #1799: Restrict `_purge` to server admin.

- #1874: This fixes inability to set keys with regex symbols in them.

- #1901: Fix badarg crash on invalid rev for individual doc update.

- #1897: Fix `from_json_obj_validate` crash when provided rev isn’t a valid hex.

- #1803: Use the same salt for admin passwords on cluster setup.

- #1053: Fix python2 compatibility for `couchup`.

- #1905: Fix python3 compatibility for `couchup`.

## 1.1.3. Version 2.3.0

### 1.1.3.1. Features

- (Multiple) Clustered purge is now available. This feature restores the CouchDB 1.x ability to completely remove any record of a document from a database. Conditions apply; to use the feature safely, and for full details, read the complete Clustered Purge documentation.

- #1658: A new config setting is available, allowing an administrator to configure an initial list of nodes that should be contacted when a node boots up. Nodes in the `seedlist` that are successfully reached will be added to that node’s `_nodes` database automatically, triggering a distributed Erlang connection and replication of the internal system databases to the new node. This can be used instead of manual config or the cluster setup wizard to bootstrap a cluster. The progress of the initial seeding of new nodes is exposed at the `GET /_up` endpoint.

- Replication supports ipv6-only peers after updating ibrowse dependency.

- #1708: The UUID of the server/cluster is once again exposed in the `GET /` response. This was a regression from CouchDB 1.x.

- #1722: Stats counts between job runs of the replicator are no longer reset on job restart.

- #1195, #1742: CouchDB’s `_bulk_get` implementation now supports the `multipart/mixed` and `multipart/related` content types if requested, extending compatibility with third-party replication clients.

### 1.1.3.2. Performance

- #1409: CouchDB no longer forces the TCP receive buffer to a fixed size of 256KB, allowing the operating system to dynamically adjust the buffer size. This can lead to siginificantly improved network performance when transferring large attachments.

- #1423: Mango selector matching now occurs at the shard level, reducing the network traffic within a cluster for a mango query.

- #1423: Long running operations at the node level could exceed the inter-node timeout, leading to a fabric timeout error in the logfile and a cancellation of the task. Nodes can now ping to stop that from happening.

- #1560: An optimization to how external data sizes of attachments were recorded was made.

- #1586: When cleaning up outdated secondary index files, the search is limited to the index directory of a specific database.

- #1593: The `couch_server` ETS table now has the `read_concurrency` option set, improving access to the global list of open database handles.

- #1593: Messages to update the least-recently used (LRU) cache are not sent when the `[couchdb] update_lru_on_read` setting is disabled.

- #1625: All nodes in a cluster now run their own `rexi` server.

### 1.1.3.3. Bugfixes

- #1484: `_stats` now correctly handles the case where a map function emits an array of integers. This bug was introduced in 2.2.0.

- #1544: Certain list functions could return a `render_error` error intermittently.

- #1550: Replicator `_session` support was incompatible with CouchDB installations using the `require_valid_user = true` setting.

- #1571: Under very heavy load, it was possible that `rexi_server` could die in such a way that it’s never restarted, leaving a cluster without the ability to issue RPC calls - effectively rendering the cluster useless.

- #1574: The built-in `_sum` reduce function has been improved to check if the objects being summed are not overflowing the view storage. Previously, there was no protection for `_sum`-introduced overflows.

- #1582: Database creation parameters now have improved validation, giving a more readable error on invalid input.

- #1588: A missing security check has been restored for the noop `/db/_ensure_full_commit` call to restore database validation checks.

- #1591: CouchDB now creates missing shard files when accessing a database if necessary. This handles the situation when, on database creation, no nodes were capable of creating any of the shard files required for that database.

- #1568: CouchDB now logs a warning if a changes feed is rewound to 0. This can help diagnose problems in busy or malfunctioning clusters.

- #1596: It is no longer possible that a busy `couch_server`, under a specific ordering and timing of events, will incorrectly track `open_async` messages in its mailbox.

- #1601, #1654: CouchDB now logs better when an error causes it to read past the EOF of a database shard. The check for whether CouchDB is trying to read too many bytes has been correctly separated out from the error indicating it has attempted to read past the EOF.

- #1613: Local nodes are now filtered out during read repair operations.

- #1636: A memory leak when replicating over HTTPS and a problem occurs has been squashed.

- #1635: `/_replicate` jobs are no longer restarted if parameters haven’t changed.

- #1612: JavaScript rewrite functions now send the body of the request to the rewritten endpoint.

- #1631: The replicator no longer crashes if the user has placed an invalid VDU function into one of the `_replicator` databases.

- #1644, #1647: It is no longer possible to create illegally-named databases within the reserved system space (`_` prefix.)

- #1650: `_bulk_get` is once again operational for system databases such as `_users`.

- #1652: Access to `/_active_tasks` is once again restricted to server admins only.

- #1662: The `couch_log` application no longer crashes when new, additional information is supplied by a crashing application, or when any of its own children are restarted.

- #1666: Mango could return an error that would crash the `couch_query_servers` application. This is no longer the case.

- #1655: Configuration of `ets_lru` in `chttpd` now performs proper error checking of the specified config value.

- #1667: The `snappy` dependency has been updated to fix a memory allocation error.

- #1683: Attempting to create a local document with an invalid revision no longer throws a `badarg` exception. Also, when setting `new_edits` to `false` and performing a bulk write operation, local documents are no longer written into the wrong btree. Finally, it is no longer possible to create a document with an empty ID during a bulk operation with `new_edits` set to `false`.

- #1721: The `couchup` convenience script for upgrading from CouchDB 1.x now also copies a database’s `_security` object on migration.

- #1672: When checking the status of a view compaction immediately after starting it, the `total_changes` and `changes_done` fields are now immediately populated with valid values.

- #1717: If the `.ini` config file is read only, an attempt to update the config through the HTTP API will now result in a proper `eacces` error response.

- #1603: CouchDB now returns the correct `total_rows` result when querying `/{db}/_design_docs`.

- #1629: Internal load validation functions no longer incorrectly hold open a deleted database or its host process.

- #1746: Server admins defined in the ini file accessing via HTTP API no longer result in the auth cache logging the access as a miss in the statistics.

- #1607: The replicator no longer fails to re-authenticate to open a remote database when its session cookie times out due to a VDU function forbidding writes or a non-standard cookie expiration duration.

- #1579: The compaction daemon no longer incorrectly only compacts a single view shard for databases with a `q` value greater than 1.

- #1737: CouchDB 2.x now performs as well as 1.x when using a `_doc_ids` or `_design_docs` filter on a changes feed.

### 1.1.3.4. Mango

### 1.1.3.5. Other

The 2.3.0 release also includes the following minor improvements:

- Improved test cases:

  - The Elixir test suite has been merged. These test cases are intended to replace the aging, unmaintainable JavaScript test suite, and help reduce our dependency on Mozilla Spidermonkey 1.8.5. The test suite does not yet cover all of the tests that the JS test suite does. Once it achieves full coverage, the JS test suite will be removed.
  - Many racy test cases improved for reliable CI runs.
  - The Makefile targets for `list-eunit-*` now work correctly on macOS.
  - #1732, #1733, #1736: All of the test suites run and pass on the Windows platform once again.

- #1597: Off-heap messages, a new feature in Erlang 19+, can now be disabled per module if desired.

- #1682: A new `[feature_flags]` config section exists for the purpose of enabling or disabling experimental features by CouchDB developers.

- A narwhal! OK, no, not really. If you got this far…thank you for reading.