From 684832aa44baf807c1ee74ec6072e5259c19c16d Mon Sep 17 00:00:00 2001
From: neethuhaneesha <nbingi@apple.com>
Date: Mon, 16 Feb 2026 11:17:32 -0800
Subject: [PATCH] Fix for minRestorableVersion and maxRestorableVersion not
 updating correctly in case of missing mutation logs. (#12710)

---
 fdbclient/BackupContainerFileSystem.actor.cpp | 30 +++++++++----------
 ...kupAndParallelRestoreCorrectness.actor.cpp | 15 ++++------
 2 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/fdbclient/BackupContainerFileSystem.actor.cpp b/fdbclient/BackupContainerFileSystem.actor.cpp
index 0ec137223f..44b135d570 100644
--- a/fdbclient/BackupContainerFileSystem.actor.cpp
+++ b/fdbclient/BackupContainerFileSystem.actor.cpp
@@ -716,24 +716,26 @@ public:
 
 			desc.snapshotBytes += s.totalSize;
 
-			// If the snapshot is at a single version then it requires no logs.  Update min and max restorable.
-			// TODO:  Somehow check / report if the restorable range is not or may not be contiguous.
-			if (s.beginVersion == s.endVersion &&
-			    (!desc.contiguousLogEnd.present() || // no logs
-			     (desc.contiguousLogEnd.present() &&
-			      desc.contiguousLogEnd.get() >= s.beginVersion)) // have logs, then should cover snapshot
-			) {
-				if (!desc.minRestorableVersion.present() || s.endVersion < desc.minRestorableVersion.get())
-					desc.minRestorableVersion = s.endVersion;
-
-				if (!desc.maxRestorableVersion.present() || s.endVersion > desc.maxRestorableVersion.get())
-					desc.maxRestorableVersion = s.endVersion;
+			// If the snapshot is at a single version and then it requires no logs.  Update min and max restorable.
+			// Update only if minRestorableVersion and maxRestorableVersion are not set. If they are set, we should
+			// check for log continuity between current minRestorableVersion to s.endVersion which happens in the
+			// next if block.
+			if (s.beginVersion == s.endVersion && !desc.minRestorableVersion.present() &&
+			    !desc.maxRestorableVersion.present()) {
+				desc.minRestorableVersion = s.endVersion;
+				desc.maxRestorableVersion = s.endVersion;
 			}
 
 			// If the snapshot is covered by the contiguous log chain then update min/max restorable.
 			if (desc.minLogBegin.present() && s.beginVersion >= desc.minLogBegin.get() &&
 			    s.endVersion < desc.contiguousLogEnd.get()) {
-				if (!desc.minRestorableVersion.present() || s.endVersion < desc.minRestorableVersion.get())
+				// If minRestorableVersion not present, update minRestorableVersion to snapshot endVersion.
+				// If minRestorableVersion present and if it has continuous logs from minRestorableVersion
+				// to snapshot endVersion, don't update the minRestorableVersion.
+				// Else, means it has no continous logs, so update minRestorableVersion to s.endVersion.
+				if (!desc.minRestorableVersion.present() ||
+				    !(desc.minRestorableVersion.get() >= desc.minLogBegin.get() &&
+				      desc.minRestorableVersion.get() < desc.contiguousLogEnd.get()))
 					desc.minRestorableVersion = s.endVersion;
 
 				if (!desc.maxRestorableVersion.present() ||
@@ -749,8 +751,6 @@ public:
 			     (desc.contiguousLogEnd.get() == s.beginVersion && s.beginVersion != s.endVersion)) &&
 			    s.restorable.get()) {
 				if (desc.minRestorableVersion.present() && desc.maxRestorableVersion.present()) {
-					ASSERT(desc.minRestorableVersion.get() < s.beginVersion);
-
 					// check if we have contiguous logs from minRestorableVersion to current snapshot endVersion
 					bool contiguousLogs = false;
 					if (desc.partitioned)
diff --git a/fdbserver/workloads/BackupAndParallelRestoreCorrectness.actor.cpp b/fdbserver/workloads/BackupAndParallelRestoreCorrectness.actor.cpp
index 690a062aac..ff0cf33f07 100644
--- a/fdbserver/workloads/BackupAndParallelRestoreCorrectness.actor.cpp
+++ b/fdbserver/workloads/BackupAndParallelRestoreCorrectness.actor.cpp
@@ -561,16 +561,11 @@ struct BackupAndParallelRestoreCorrectnessWorkload : TestWorkload {
 						targetVersion = desc.minRestorableVersion.get();
 					} else if (deterministicRandom()->random01() < 0.1) {
 						targetVersion = desc.maxRestorableVersion.get();
-					} else if (deterministicRandom()->random01() < 0.5 &&
-					           desc.minRestorableVersion.get() < desc.contiguousLogEnd.get()) {
-						// The assertion may fail because minRestorableVersion may be decided by snapshot version.
-						// ASSERT_WE_THINK(desc.minRestorableVersion.get() <= desc.contiguousLogEnd.get());
-						// This assertion can fail when contiguousLogEnd < maxRestorableVersion and
-						// the snapshot version > contiguousLogEnd. I.e., there is a gap between
-						// contiguousLogEnd and snapshot version.
-						// ASSERT_WE_THINK(desc.contiguousLogEnd.get() > desc.maxRestorableVersion.get());
-						targetVersion = deterministicRandom()->randomInt64(desc.minRestorableVersion.get(),
-						                                                   desc.contiguousLogEnd.get());
+					} else if (deterministicRandom()->random01() < 0.5) {
+						targetVersion = (desc.minRestorableVersion.get() != desc.maxRestorableVersion.get())
+						                    ? deterministicRandom()->randomInt64(desc.minRestorableVersion.get(),
+						                                                         desc.maxRestorableVersion.get())
+						                    : desc.maxRestorableVersion.get();
 					}
 				}