Bugfix release.

[BUGFIX] Notifier: could hang when using relabeling on alerts #13861

Bugfix release.

• [BUGFIX] PromQL: Re-instate validation of label_join destination label #13803
• [BUGFIX] Scraping (experimental native histograms): Fix handling of the min bucket factor on sync of targets #13846
• [BUGFIX] PromQL: Some queries could return the same series twice (library use only) #13845

Special release build that incorporates performance improvements using
the dedupelabels Go tag. The new labels data structure deduplicates label names
and values via symbol or intern tables, reducing memory usage.

This version is built with Go 1.22.1.

There is a new optional build tag "dedupelabels", which should reduce memory consumption (#12304).
It is off by default; there will be an optional alternative image to try it out.

• [CHANGE] Scraping: Do experimental timestamp alignment even if tolerance is bigger than 1% of scrape interval #13624, #13737
• [FEATURE] Alerting: Relabel rules for AlertManagerConfig; allows routing alerts to different alertmanagers #12551, #13735
• [FEATURE] API: add limit param to series, label-names and label-values APIs #13396
• [FEATURE] UI (experimental native histograms): Add native histogram chart to Table view #13658
• [FEATURE] Promtool: Add a "tsdb dump-openmetrics" to dump in OpenMetrics format. #13194
• [FEATURE] PromQL (experimental native histograms): Add histogram_avg function #13467
• [ENHANCEMENT] Rules: Evaluate independent rules concurrently #12946, #13527
• [ENHANCEMENT] Scraping (experimental native histograms): Support exemplars #13488
• [ENHANCEMENT] Remote Write: Disable resharding during active retry backoffs #13562
• [ENHANCEMENT] Observability: Add native histograms to latency/duration metrics #13681
• [ENHANCEMENT] Observability: Add 'type' label to prometheus_tsdb_head_out_of_order_samples_appended_total #13607
• [ENHANCEMENT] API: Faster generation of targets into JSON #13469, #13484
• [ENHANCEMENT] Scraping, API: Use faster compression library #10782
• [ENHANCEMENT] OpenTelemetry: Performance improvements in OTLP parsing #13627
• [ENHANCEMENT] PromQL: Optimisations to reduce CPU and memory #13448, #13536
• [BUGFIX] PromQL: Constrain extrapolation in rate() to half of sample interval #13725
• [BUGFIX] Remote Write: Stop slowing down when a new WAL segment is created #13583, #13628
• [BUGFIX] PromQL: Fix wrongly scoped range vectors with @ modifier #13559
• [BUGFIX] Kubernetes SD: Pod status changes were not discovered by Endpoints service discovery #13337
• [BUGFIX] Azure SD: Fix 'error: parameter virtualMachineScaleSetName cannot be empty' (#13702)
• [BUGFIX] Remote Write: Fix signing for AWS sigv4 transport #13497
• [BUGFIX] Observability: Exemplars emitted by Prometheus use "trace_id" not "traceID" #13589

• [BUGFIX] Remote read: Release querier resources before encoding the results. #13777

Special release candidate build that incorporates performance improvements using
the dedupelabels Go tag. The new labels data structure deduplicates label names
and values via symbol or intern tables, reducing memory usage.

This version is built with Go 1.22.1.

There is a new optional build tag "dedupelabels", which should reduce memory consumption (#12304).
It is off by default; there is an optional alternative image prom/prometheus:v2.51.0-rc.0-dedupelabels to try it out.

• [CHANGE] Scraping: Do experimental timestamp alignment even if tolerance is bigger than 1% of scrape interval #13624, #13737
• [FEATURE] Alerting: Relabel rules for AlertManagerConfig; allows routing alerts to different alertmanagers #12551, #13735
• [FEATURE] API: add limit param to series, label-names and label-values APIs #13396
• [FEATURE] UI (experimental native histograms): Add native histogram chart to Table view #13658
• [FEATURE] Promtool: Add a "tsdb dump-openmetrics" to dump in OpenMetrics format. #13194
• [FEATURE] PromQL (experimental native histograms): Add histogram_avg function #13467
• [ENHANCEMENT] Rules: Evaluate independent rules concurrently #12946, #13527
• [ENHANCEMENT] Scraping (experimental native histograms): Support exemplars #13488
• [ENHANCEMENT] Remote Write: Disable resharding during active retry backoffs #13562
• [ENHANCEMENT] Observability: Add native histograms to latency/duration metrics #13681
• [ENHANCEMENT] Observability: Add 'type' label to prometheus_tsdb_head_out_of_order_samples_appended_total #13607
• [ENHANCEMENT] API: Faster generation of targets into JSON #13469, #13484
• [ENHANCEMENT] Scraping, API: Use faster compression library #10782
• [ENHANCEMENT] OpenTelemetry: Performance improvements in OTLP parsing #13627
• [ENHANCEMENT] PromQL: Optimisations to reduce CPU and memory #13448, #13536
• [BUGFIX] PromQL: Constrain extrapolation in rate() to half of sample interval #13725
• [BUGFIX] Remote Write: Stop slowing down when a new WAL segment is created #13583, #13628
• [BUGFIX] PromQL: Fix wrongly scoped range vectors with @ modifier #13559
• [BUGFIX] Kubernetes SD: Pod status changes were not discovered by Endpoints service discovery #13337
• [BUGFIX] Azure SD: Fix 'error: parameter virtualMachineScaleSetName cannot be empty' (#13702)
• [BUGFIX] Remote Write: Fix signing for AWS sigv4 transport #13497
• [BUGFIX] Observability: Exemplars emitted by Prometheus use "trace_id" not "traceID" #13589

This is a bug-fix release for an issue that broke the /metadata API.

• [BUGFIX] API: Fix metadata API using wrong field names. #13633

Thanks to @itsmylife for the fix.

• [CHANGE] Remote Write: Error storage.ErrTooOldSample is now generating HTTP error 400 instead of HTTP error 500. #13335
• [FEATURE] Remote Write: Drop old inmemory samples. Activated using the config entry sample_age_limit. #13002
• [FEATURE] Experimental: Add support for ingesting zeros as created timestamps. (enabled under the feature-flag created-timestamp-zero-ingestion). #12733 #13279
• [FEATURE] Promtool: Add analyze histograms command. #12331
• [FEATURE] TSDB/compaction: Add a way to enable overlapping compaction. #13282 #13393 #13398
• [FEATURE] Add automatic memory limit handling. Activated using the feature flag. auto-gomemlimit #13395
• [ENHANCEMENT] Promtool: allow specifying multiple matchers in promtool tsdb dump. #13296
• [ENHANCEMENT] PromQL: Restore more efficient version of NewPossibleNonCounterInfo annotation. #13022
• [ENHANCEMENT] Kuma SD: Extend configuration to allow users to specify client ID. #13278
• [ENHANCEMENT] PromQL: Use natural sort in sort_by_label and sort_by_label_desc. This is experimental. #13411
• [ENHANCEMENT] Native Histograms: support native_histogram_min_bucket_factor in scrape_config. #13222
• [ENHANCEMENT] Native Histograms: Issue warning if histogramRate is applied to the wrong kind of histogram. #13392
• [ENHANCEMENT] TSDB: Make transaction isolation data structures smaller. #13015
• [ENHANCEMENT] TSDB/postings: Optimize merge using Loser Tree. #12878
• [ENHANCEMENT] TSDB: Simplify internal series delete function. #13261
• [ENHANCEMENT] Agent: Performance improvement by making the global hash lookup table smaller. #13262
• [ENHANCEMENT] PromQL: faster execution of metric functions, e.g. abs(), rate() #13446
• [ENHANCEMENT] TSDB: Optimize label values with matchers by taking shortcuts. #13426
• [ENHANCEMENT] Kubernetes SD: Check preconditions earlier and avoid unnecessary checks or iterations in kube_sd. #13408
• [ENHANCEMENT] Promtool: Improve visibility for promtool test rules with JSON colored formatting. #13342
• [ENHANCEMENT] Consoles: Exclude iowait and steal from CPU Utilisation. #9593
• [ENHANCEMENT] Various improvements and optimizations on Native Histograms. #13267, #13215, #13276 #13289, #13340
• [BUGFIX] Scraping: Fix quality value in HTTP Accept header. #13313
• [BUGFIX] UI: Fix usage of the function time() that was crashing. #13371
• [BUGFIX] Azure SD: Fix SD crashing when it finds a VM scale set. #13578

[BUGFIX] Azure SD: Fix SD crashing when it finds a VM scale set. #13578