From 2828c543bc9c6d4f262fc57336abfc7a284e57a1 Mon Sep 17 00:00:00 2001
From: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>
Date: Thu, 2 Apr 2026 10:26:48 +0200
Subject: [PATCH] tsdb: reduce chunk segment size in
 TestDiskFillingUpAfterDisablingOOO

The test only writes ~80 samples, so the default 512MB chunk segment
pre-allocation during compaction is unnecessary. Use 1MB instead to
avoid large file allocations on constrained CI environments.

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>
---
 tsdb/db_test.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tsdb/db_test.go b/tsdb/db_test.go
index 2ca2f70529..1758518e6f 100644
--- a/tsdb/db_test.go
+++ b/tsdb/db_test.go
@@ -8361,6 +8361,10 @@ func testDiskFillingUpAfterDisablingOOO(t *testing.T, scenario sampleTypeScenari
 	// (important for slow CI like i386 which can be 60x+ slower).
 	opts.SamplesPerChunk = 15
 	opts.OutOfOrderCapMax = 5
+	// Reduce the chunk segment size from the 512MB default: the test only writes
+	// ~80 samples so 1MB is sufficient and avoids large file pre-allocations
+	// during compaction on slow or constrained CI environments.
+	opts.MaxBlockChunkSegmentSize = 1024 * 1024
 
 	db := newTestDB(t, withOpts(opts))
 	db.DisableCompactions()