From 67a3cbb31a8fe3f4b4d6132a0f4f321beb5dcaca Mon Sep 17 00:00:00 2001
From: Joe Elliott <number101010@gmail.com>
Date: Fri, 25 Oct 2024 15:45:51 -0400
Subject: [PATCH] changelog, docs and lint

Signed-off-by: Joe Elliott <number101010@gmail.com>
---
 CHANGELOG.md                         | 1 +
 docs/sources/tempo/traceql/_index.md | 9 +++++++++
 modules/frontend/search_sharder.go   | 6 ++++--
 pkg/traceql/combine.go               | 1 -
 4 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e58871a3e44..32d1c662a6c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -41,6 +41,7 @@
 * [ENHANCEMENT] Speedup collection of results from ingesters in the querier [#4100](https://github.com/grafana/tempo/pull/4100) (@electron0zero)
 * [ENHANCEMENT] Speedup DistinctValue collector and exit early for ingesters [#4104](https://github.com/grafana/tempo/pull/4104) (@electron0zero)
 * [ENHANCEMENT] Add disk caching in ingester SearchTagValuesV2 for completed blocks [#4069](https://github.com/grafana/tempo/pull/4069) (@electron0zero)
+* [ENHANCEMENT] Added most_recent=true query hint to TraceQL to return most recent results. [#4238](https://github.com/grafana/tempo/pull/4238) (@joe-elliott)
 * [BUGFIX] Replace hedged requests roundtrips total with a counter. [#4063](https://github.com/grafana/tempo/pull/4063) [#4078](https://github.com/grafana/tempo/pull/4078) (@galalen)
 * [BUGFIX] Metrics generators: Correctly drop from the ring before stopping ingestion to reduce drops during a rollout. [#4101](https://github.com/grafana/tempo/pull/4101) (@joe-elliott)
 * [BUGFIX] Correctly handle 400 Bad Request and 404 Not Found in gRPC streaming [#4144](https://github.com/grafana/tempo/pull/4144) (@mapno)
diff --git a/docs/sources/tempo/traceql/_index.md b/docs/sources/tempo/traceql/_index.md
index cc97015b423..1742f259d2d 100644
--- a/docs/sources/tempo/traceql/_index.md
+++ b/docs/sources/tempo/traceql/_index.md
@@ -451,6 +451,15 @@ TraceQL can select arbitrary fields from spans. This is particularly performant
 { status=error } | select(span.http.status_code, span.http.url)
 ```
 
+## Retrieving most recent results (experimental)
+
+The TraceQL query hint `most_recent=true` can be used with any TraceQL selection query to force Tempo to return the most recent results ordered by time. Examples:
+
+```
+{} with (most_recent=true)
+{ span.foo = "bar" } >> { status = error } with (most_recent=true)
+```
+
 ## Experimental TraceQL metrics
 
 TraceQL metrics are experimental, but easy to get started with. Refer to [the TraceQL metrics]({{< relref "../operations/traceql-metrics.md" >}}) documentation for more information.
diff --git a/modules/frontend/search_sharder.go b/modules/frontend/search_sharder.go
index 16fd6f48fcc..6fe03ad11e1 100644
--- a/modules/frontend/search_sharder.go
+++ b/modules/frontend/search_sharder.go
@@ -405,8 +405,10 @@ func buildIngesterRequestChan(ctx context.Context, tenantID string, parent pipel
 	return nil
 }
 
-type shardIterFn func(jobs int, sz uint64, completedThroughTime uint32)
-type jobIterFn func(m *backend.BlockMeta, shard, startPage, pages int)
+type (
+	shardIterFn func(jobs int, sz uint64, completedThroughTime uint32)
+	jobIterFn   func(m *backend.BlockMeta, shard, startPage, pages int)
+)
 
 // backendJobsFunc provides an iter func with 2 callbacks designed to be used once to calculate job and shard metrics and a second time
 // to generate actual jobs.
diff --git a/pkg/traceql/combine.go b/pkg/traceql/combine.go
index 1c7ab688a06..a25b01619e0 100644
--- a/pkg/traceql/combine.go
+++ b/pkg/traceql/combine.go
@@ -22,7 +22,6 @@ type MetadataCombiner interface {
 }
 
 const TimestampNever = uint32(math.MaxUint32)
-const TimestampAllTime = uint32(1)
 
 func NewMetadataCombiner(limit int, keepMostRecent bool) MetadataCombiner {
 	if keepMostRecent {