Release 2.54 brings a release candidate of a major new version of Remote Write: 2.0. This is experimental at this time and may still change. Remote-write v2 is enabled by default, but can be disabled via feature-flag web.remote-write-receiver.accepted-protobuf-messages.

• [CHANGE] Remote-Write: highest_timestamp_in_seconds and queue_highest_sent_timestamp_seconds metrics now initialized to 0. #14437
• [CHANGE] API: Split warnings from info annotations in API response. #14327
• [FEATURE] Remote-Write: Version 2.0 experimental, plus metadata in WAL via feature flag metadata-wal-records (defaults on). #14395,#14427,#14444
• [FEATURE] PromQL: add limitk() and limit_ratio() aggregation operators. #12503
• [ENHANCEMENT] PromQL: Accept underscores in literal numbers, e.g. 1_000_000 for 1 million. #12821
• [ENHANCEMENT] PromQL: float literal numbers and durations are now interchangeable (experimental). Example: time() - my_timestamp > 10m. #9138
• [ENHANCEMENT] PromQL: use Kahan summation for sum(). #14074,#14362
• [ENHANCEMENT] PromQL (experimental native histograms): Optimize histogram_count and histogram_sum functions. #14097
• [ENHANCEMENT] TSDB: Better support for out-of-order experimental native histogram samples. #14438
• [ENHANCEMENT] TSDB: Optimise seek within index. #14393
• [ENHANCEMENT] TSDB: Optimise deletion of stale series. #14307
• [ENHANCEMENT] TSDB: Reduce locking to optimise adding and removing series. #13286,#14286
• [ENHANCEMENT] TSDB: Small optimisation: streamline special handling for out-of-order data. #14396,#14584
• [ENHANCEMENT] Regexps: Optimize patterns with multiple prefixes. #13843,#14368
• [ENHANCEMENT] Regexps: Optimize patterns containing multiple literal strings. #14173
• [ENHANCEMENT] AWS SD: expose Primary IPv6 addresses as __meta_ec2_primary_ipv6_addresses. #14156
• [ENHANCEMENT] Docker SD: add MatchFirstNetwork for containers with multiple networks. #10490
• [ENHANCEMENT] OpenStack SD: Use flavor.original_name if available. #14312
• [ENHANCEMENT] UI (experimental native histograms): more accurate representation. #13680,#14430
• [ENHANCEMENT] Agent: out_of_order_time_window config option now applies to agent. #14094
• [ENHANCEMENT] Notifier: Send any outstanding Alertmanager notifications when shutting down. #14290
• [ENHANCEMENT] Rules: Add label-matcher support to Rules API. #10194
• [ENHANCEMENT] HTTP API: Add url to message logged on error while sending response. #14209
• [BUGFIX] CLI: escape | characters when generating docs. #14420
• [BUGFIX] PromQL (experimental native histograms): Fix some binary operators between native histogram values. #14454
• [BUGFIX] TSDB: LabelNames API could fail during compaction. #14279
• [BUGFIX] TSDB: Fix rare issue where pending OOO read can be left dangling if creating querier fails. #14341
• [BUGFIX] TSDB: fix check for context cancellation in LabelNamesFor. #14302
• [BUGFIX] Rules: Fix rare panic on reload. #14366
• [BUGFIX] Config: In YAML marshalling, do not output a regexp field if it was never set. #14004
• [BUGFIX] Remote-Write: reject samples with future timestamps. #14304
• [BUGFIX] Remote-Write: Fix data corruption in remote write if max_sample_age is applied. #14078
• [BUGFIX] Notifier: Fix Alertmanager discovery not updating under heavy load. #14174
• [BUGFIX] Regexes: some Unicode characters were not matched by case-insensitive comparison. #14170,#14299
• [BUGFIX] Remote-Read: Resolve occasional segmentation fault on query. #14515

Many thanks to the Prometheus Team and contributors: @zenador @jjo @rexagod @darshanime @charleskorn @fpetkovski @carrieedwards @colega
@pracucci @akunszt @DrAuYueng @paulojmdias @Maniktherana @rabenhorst
@saswatamcode @B1F030 @yeya24 @rapphil @liam-howe-maersk @jkroepke @FUSAKLA @Ranveer777