From de084ae0e7adeafbcc8fcac30b9bf3fdf10481ff Mon Sep 17 00:00:00 2001
From: Linas Medziunas <linas.medziunas@gmail.com>
Date: Tue, 18 Nov 2025 12:06:32 +0200
Subject: [PATCH] [PromQL] Improve BenchmarkJoinQuery

Signed-off-by: Linas Medziunas <linas.medziunas@gmail.com>
---
 promql/bench_test.go | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/promql/bench_test.go b/promql/bench_test.go
index 37c8311305..a15f19e17e 100644
--- a/promql/bench_test.go
+++ b/promql/bench_test.go
@@ -393,40 +393,44 @@ func BenchmarkJoinQuery(b *testing.B) {
 	}
 	engine := promqltest.NewTestEngineWithOpts(b, opts)
 
-	const interval = 10000 // 10s interval.
+	const (
+		interval     = 10000 // 10s interval.
+		steps        = 5000
+		numInstances = 1000
+	)
 
-	// A day of data plus 10k steps.
-	numIntervals := 8640 + 10000
+	// A day of data plus steps.
+	numIntervals := 8640 + steps
 
-	require.NoError(b, setupJoinQueryTestData(stor, engine, interval, numIntervals, 1000))
+	require.NoError(b, setupJoinQueryTestData(stor, engine, interval, numIntervals, numInstances))
 
 	for _, c := range []benchCase{
 		{
 			expr:  `rpc_request_success_total + rpc_request_error_total`,
-			steps: 10000,
+			steps: steps,
 		},
 		{
 			expr:  `rpc_request_success_total + ON (job, instance) GROUP_LEFT rpc_request_error_total`,
-			steps: 10000,
+			steps: steps,
 		},
 		{
 			expr:  `rpc_request_success_total AND rpc_request_error_total{instance=~"0.*"}`, // 0.* keeps 1/16 of UUID values
-			steps: 10000,
+			steps: steps,
 		},
 		{
 			expr:  `rpc_request_success_total OR rpc_request_error_total{instance=~"0.*"}`, // 0.* keeps 1/16 of UUID values
-			steps: 10000,
+			steps: steps,
 		},
 		{
 			expr:  `rpc_request_success_total UNLESS rpc_request_error_total{instance=~"0.*"}`, // 0.* keeps 1/16 of UUID values
-			steps: 10000,
+			steps: steps,
 		},
 	} {
 		name := fmt.Sprintf("expr=%s/steps=%d", c.expr, c.steps)
 		b.Run(name, func(b *testing.B) {
 			ctx := context.Background()
-			b.ReportAllocs()
-			for b.Loop() {
+
+			queryFn := func() {
 				qry, err := engine.NewRangeQuery(
 					ctx, stor, nil, c.expr,
 					timestamp.Time(int64((numIntervals-c.steps)*10_000)),
@@ -439,6 +443,14 @@ func BenchmarkJoinQuery(b *testing.B) {
 
 				qry.Close()
 			}
+
+			queryFn() // Warm up run.
+
+			b.ResetTimer()
+			b.ReportAllocs()
+			for b.Loop() {
+				queryFn()
+			}
 		})
 	}
 }