Fix Discover query

2 files changed, 26 insertions, 7 deletions

diff --git a/ydb/core/blob_depot/agent/storage_discover.cpp b/ydb/core/blob_depot/agent/storage_discover.cpp
index db1ea8f96b..27bfab0593 100644
--- a/ydb/core/blob_depot/agent/storage_discover.cpp
+++ b/ydb/core/blob_depot/agent/storage_discover.cpp
@@ -18,6 +18,9 @@ namespace NKikimr::NBlobDepot {
 
             std::unordered_set<TString> ValueChainsWithNodata;
             TString ValueChain;
+            bool IsUnassimilated = false;
+
+            NKikimrBlobDepot::TEvResolve Resolve;
 
         public:
             using TBlobStorageQuery::TBlobStorageQuery;
@@ -26,6 +29,7 @@ namespace NKikimr::NBlobDepot {
                 BDEV_QUERY(BDEV16, "TEvDiscover_begin", (U.TabletId, Request.TabletId), (U.ReadBody, Request.ReadBody),
                     (U.MinGeneration, Request.MinGeneration));
 
+                GenerateInitialResolve();
                 IssueResolve();
 
                 if (Request.DiscoverBlockedGeneration) {
@@ -40,13 +44,12 @@ namespace NKikimr::NBlobDepot {
                 }
             }
 
-            void IssueResolve() {
+            void GenerateInitialResolve() {
                 const ui8 channel = 0;
                 const TLogoBlobID from(Request.TabletId, Request.MinGeneration, 0, channel, 0, 0);
                 const TLogoBlobID to(Request.TabletId, Max<ui32>(), Max<ui32>(), channel, TLogoBlobID::MaxBlobSize, TLogoBlobID::MaxCookie);
 
-                NKikimrBlobDepot::TEvResolve resolve;
-                auto *item = resolve.AddItems();
+                auto *item = Resolve.AddItems();
                 auto *range = item->MutableKeyRange();
                 range->SetBeginningKey(from.AsBinaryString());
                 range->SetIncludeBeginning(true);
@@ -56,8 +59,10 @@ namespace NKikimr::NBlobDepot {
                 range->SetReverse(true);
                 item->SetTabletId(Request.TabletId);
                 item->SetMustRestoreFirst(true);
+            }
 
-                Agent.Issue(std::move(resolve), this, nullptr);
+            void IssueResolve() {
+                Agent.Issue(Resolve, this, nullptr);
             }
 
             void ProcessResponse(ui64 id, TRequestContext::TPtr context, TResponse response) override {
@@ -111,6 +116,8 @@ namespace NKikimr::NBlobDepot {
                                 return EndWithError(NKikimrProto::ERROR, TStringBuilder() << "empty ValueChain");
                             }
                             ValueChain = GetValueChainId(item.GetValueChain());
+                            IsUnassimilated = item.ValueChainSize() == 1 && item.GetValueChain(0).GetGroupId() == Agent.DecommitGroupId &&
+                                LogoBlobIDFromLogoBlobID(item.GetValueChain(0).GetBlobId()) == Id;
                             TReadArg arg{
                                 item.GetValueChain(),
                                 NKikimrBlobStorage::Discover,
@@ -153,6 +160,13 @@ namespace NKikimr::NBlobDepot {
                     if (ValueChainsWithNodata.insert(std::exchange(ValueChain, {})).second) {
                         // this may indicate a data race between locator and key value, we have to restart our resolution query
                         IssueResolve();
+                    } else if (IsUnassimilated) {
+                        // we are reading blob from the original group and it may be partially written -- it is totally
+                        // okay to have some; we need to advance to the next readable blob
+                        auto *range = Resolve.MutableItems(0)->MutableKeyRange();
+                        range->SetEndingKey(Id.AsBinaryString());
+                        range->ClearIncludeEnding();
+                        IssueResolve();
                     } else {
                         Y_VERIFY_DEBUG_S(false, "data is lost AgentId# " << Agent.LogId << " BlobId# " << Id);
                         STLOG(PRI_CRIT, BLOB_DEPOT_AGENT, BDA39, "failed to Discover blob -- data is lost",
diff --git a/ydb/core/blob_depot/blob_depot_tablet.h b/ydb/core/blob_depot/blob_depot_tablet.h
index e229220259..d2efc2bff7 100644
--- a/ydb/core/blob_depot/blob_depot_tablet.h
+++ b/ydb/core/blob_depot/blob_depot_tablet.h
@@ -202,11 +202,16 @@ namespace NKikimr::NBlobDepot {
         TString GetLogId() const {
             const auto *executor = Executor();
             const ui32 generation = executor ? executor->Generation() : 0;
+            TStringBuilder sb;
+            sb << '{' << TabletID();
             if (Config.HasVirtualGroupId()) {
-                return TStringBuilder() << "{" << TabletID() << ":" << generation << "@" << Config.GetVirtualGroupId() << "}";
-            } else {
-                return TStringBuilder() << "{" << TabletID() << ":" << generation << "}";
+                sb << '@' << Config.GetVirtualGroupId();
+            }
+            sb << '}';
+            if (generation) {
+                sb << ':' << generation;
             }
+            return sb;
         }
 
         ////////////////////////////////////////////////////////////////////////////////////////////////////////////////