1.1. 3.5.x Branch
1.1.1. Version 3.5.0
1.1.1.1. Highlights
#5399, #5441, #5443, #5460, #5461: Implement parallel
preadcalls: lets clients issue concurrentpreadcalls without blocking each other or having to wait for all writes andfsynccalls. This is enabled by default and can be disabled with[couchdb] use_cfile = falsein the configuration.CouchDB already employs a multiple-parallel-read and concurrent serial-write design at the database engine layer, but below that in the storage engine, each file representing a database shard is required to route all read / write / sync requests through a single Erlang process that owns the file descriptor (fd).
An Erlang process can at most execute at the speed of a single CPU core. Two scenarios can lead to a starvation of the fd-owning Erlang process message inbox:
1000s of concurrent read requests with a constant stream of writes per shard, or:
a high latency storage devices like network block storage.
Parallel preads re-implements the Erlang
filemodule in parts ascouch_cfileto allow multipledup()’d file descriptors to be used for reading and writing. Writes continue to be serialised at the database engine layer, but reads now are no longer blocked by writes waiting to commit.Comes with an extensive test suite that includes property testing to ensure
couch_cfilebehaves exactly like Erlang’sfilein all other cases.Performance is always equal or better than before. These scenarios show preliminary improvements:
random document reads: 15% more throughput
read
_all_docs: 15% more throughputread
_all_docswithinclude_docs=true: 25% more throughputread
_changes: 4% more throughputsingle document writes: 8% more throughput
2000x concurrent clients, random document reads on a 12 node cluster: 30% more throughput
concurrent constant document writes and concurrent single document reads on a single shard: 40% more throughput.
This feature is not available on Windows.
#5435: Improve default
chttpd_serveroptions. This helps with faster processing of many concurrent TCP connections.#5347: Fix attachment size calculation. This could lead to shards not being scheduled for compaction correctly.
#5494: Implement
_top_Nand_bottom_Nreducers. These reducers return the top or bottom values from a map-reduce view.Nis a number between1and100. For instance, a_top_5reducer will return the top 5 highest values for a group level.#5498: Implement
_firstand_lastreducers. These reducers return the first, and respectively, the last view row for a given group level. For example,_lastcan be used to retrieve the last timestamp update for eachdevice_idif we had a key like[device_id, timestamp]if we query the view withgroup_level=1.#5466: Conflict finder plugin. Enable the
couch_scanner_plugin_conflict_finderplugin to find conflicting docs across all the databases. It can be configured to report individual revisions or aggregated statistics.
1.1.1.2. Performance
#5499: QuickJS rope based string implementation.
#5451: Optimize config system to use persistent terms.
#5437: Fix
atts_sincefunctionality for documentGETrequests. Avoids re-replicating attachment bodies on doc updates.#5398: Save 1
writefor each committing data to disk by usingfdatasyncwhile keeping the same level of storage reliability.
1.1.1.3. Features
#5526: Default
upgrade_hash_on_authtotrue. Downgrading to3.4.1,3.4.2, or3.4.3is safe. Those versions know how to verify these new password hashes.#5517: Enable xxHash file checksums by default. Downgrading to
3.4.xversions should be safe. Those versions know how to read and verify xxHash checksums.#5527: Update Fauxton and xxHash dependencies.
#5525: Array opcode optimization for QuickJS.
#5518: More precise error location reporting for QuickJS.
#5516: Detailed node membership info for Prometheus.
#5489: Allow TLS client certs for Nouveau requests.
#5452:
BigIntsupport for QuickJS.#5439: Nouveau: upgrade
dropwizardto 4.0.12.#5429: Add
simple+pbkdf2migration password scheme.#5424: Scanner: reduce log noise, fix QuickJS plugin mocks, gracefully handle broken search indexes.
#5421: Nouveau: upgrade Lucene to 9.12.1.
#5414: Remove unused
multi_workersoption fromcouch_work_queue.#5402: Remove unused, undocumented and detrimental idle check timeout feature.
#5395: Remove unused, undocumented and unreliabele
pread_limitfeature fromcouch_file.#5385: Clean up
fabric_doc_updateby introducing an#accrecord.#5372: Upgrade to Elixir 1.17.
#5351: Clouseau: show version in
/_versionendpoint.#5338: Scanner: add Nouveau and Clouseau design doc validation.
#5335: Nouveau: support reading older Lucene 9x indexes.
#5327, #5329, #5419: Allow switching JavaScript engines at runtime.
#5326, #5328: Allow clients to specify HTTP request ID, including UUIDs.
#5321, #5366, #5413: Add support for SpiderMonkey versions 102, 115 and 128.
#5317: Add quickjs to the list of welcome features.
1.1.1.4. Bugfixes
#5515: Make sure
query_limitconfig takes effect. Raise default limit from2^28to2^59. Allowinfinityas a more ergonomic config value.#5522: Reopen indexes closed by Lucene in Nouveau.
#5508: Fix array
from()andat()for QuickJS.#5502: Buffer overflow and segfault fix in QuickJS.
#5463: Fix
badarithin Nouveau index query.#5447: Fix arithmetic mean in
_prometheus.#5440: Fix
_purged_infoswhen exceedingpurged_infos_limit.#5431: Restore the ability to return
Errorobjects from map().#5417: Clouseau: add a version check to
connected()function to reliably detect if a Clouseau node is ready to be used.#5416: Ensure we always map the documents in order in
couch_mrview_updater. While views still built correctly, this behaviour simplifies debugging.#5373: Fix checksumming in
couch_file, consolidate similar functions and bring test coverage from 66% to 90%.#5367: Scanner: be more resilient in the face of non-deterministic functions.
#5345: Scanner: be more resilient in the face of incomplete sample data.
#5344: Scanner: allow empty doc fields.
#5341: Improve Mango test reliability.
#5337: Prevent a broken
mem3app from permanently failing replication.#5334: Fix QuickJS scanner
function_clauseerror.#5332: Skip deleted documents in the scanner.
#5331: Skip validation for design docs in the scanner.
#5330: Prevent inserting illegal design docs via Mango.
1.1.1.5. Docs
#5433: Mango: document Nouveau index type.
#5432: Add conceptual docs for Mango.
#5428: Fix wrong link in example in
CONTRIBUTING.md.#5400: Clarify RHEL9 installation caveats.
#5338: Clouseau: document version in
/_versionendpoint.#5316, #5325, #5426, #5442, #5445: Document various JavaScript engine incompatibilities, including SpiderMonkey 1.8.5 vs. newer SpiderMonkey and SpiderMonkey vs. QuickJS.
#5323: Nouveau: improve install instructions.
1.1.1.5.1. Tests
1.1.1.6. Builds
#5360: Use
brew --prefixto find ICU paths on macOS.
1.1.1.7. Other
There’s always IOPS in the banana stand.