From 669c3a6f6abae948c727d4158b68a67ac84c61fd Mon Sep 17 00:00:00 2001
From: Chris Lu <chrislusf@users.noreply.github.com>
Date: Wed, 7 Oct 2026 09:59:05 -0700
Subject: [PATCH] iceberg maintenance: keep ordered runs when the full repack
 yields nothing

The bestEffort leftover fallback removed the ordered runs before checking
whether repacking the whole bin produced any bins, discarding valid
compaction work.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
---
 weed/worker/tasks/iceberg/compact.go          | 11 +++++----
 .../tasks/iceberg/compact_order_test.go       | 23 +++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/weed/worker/tasks/iceberg/compact.go b/weed/worker/tasks/iceberg/compact.go
index d7ca2ef14c..eb99e68ca9 100644
--- a/weed/worker/tasks/iceberg/compact.go
+++ b/weed/worker/tasks/iceberg/compact.go
@@ -598,10 +598,13 @@ func buildCompactionBins(entries []iceberg.ManifestEntry, targetSize int64, minF
 				packed := splitOversizedBin(runtBin, targetSize, minFiles)
 				if len(packed) == 0 {
 					// Stragglers cannot merge even with each other; repacking
-					// the whole bin lets them pair across the ordered runs
-					// instead of stranding them for every later pass.
-					result = result[:len(result)-len(runs)]
-					packed = splitOversizedBin(*bin, targetSize, minFiles)
+					// the whole bin lets them pair across the ordered runs.
+					// Only replace the runs when the repack yields bins —
+					// otherwise the runs stay valid compaction work.
+					if full := splitOversizedBin(*bin, targetSize, minFiles); len(full) > 0 {
+						result = result[:len(result)-len(runs)]
+						packed = full
+					}
 				}
 				result = append(result, packed...)
 			}
diff --git a/weed/worker/tasks/iceberg/compact_order_test.go b/weed/worker/tasks/iceberg/compact_order_test.go
index 32a673dccc..8a4b1fdf78 100644
--- a/weed/worker/tasks/iceberg/compact_order_test.go
+++ b/weed/worker/tasks/iceberg/compact_order_test.go
@@ -363,3 +363,26 @@ func TestResolveCompactionOrderSkipsUncoveredSortField(t *testing.T) {
 		t.Fatalf("uncovered sort field: got %+v, want nil", order)
 	}
 }
+// A full-bin repack that produces nothing must not discard the ordered runs
+// it was meant to replace — they are still valid compaction work.
+func TestCompactDataFilesKeepsRunsWhenRepackFails(t *testing.T) {
+	fs, client := startFakeFiler(t)
+	setup := tableSetup{BucketName: "tb", Namespace: "ns", TableName: "tbl"}
+	populateBoundedTable(t, fs, setup, []boundedFile{
+		{Name: "r1.parquet", IDs: []int64{1}, Lower: 1, Upper: 2, SizeBytes: 4 << 20},
+		{Name: "r2.parquet", IDs: []int64{3}, Lower: 3, Upper: 4, SizeBytes: 3 << 20},
+		{Name: "r3.parquet", IDs: []int64{5}, Lower: 5, Upper: 6, SizeBytes: 3 << 20},
+		{Name: "r4.parquet", IDs: []int64{7}, Lower: 7, Upper: 8, SizeBytes: 6 << 20},
+		{Name: "r5.parquet", IDs: []int64{9}, Lower: 9, Upper: 10, SizeBytes: 6 << 20},
+	})
+
+	handler := NewHandler(nil)
+	config := Config{TargetFileSizeBytes: 10 << 20, MinInputFiles: 3, MaxCommitRetries: 3}
+	result, _, err := handler.compactDataFiles(context.Background(), client, setup.BucketName, setup.tablePath(), config, nil)
+	if err != nil {
+		t.Fatalf("compactDataFiles: %v", err)
+	}
+	if !strings.Contains(result, "compacted 3 files into 1") {
+		t.Fatalf("expected the ordered run to survive the failed repack, got %q", result)
+	}
+}