Smaller memory footprint for shards info (#9207)

3 files changed, 44 insertions, 14 deletions

diff --git a/ydb/core/kqp/common/kqp_tx.cpp b/ydb/core/kqp/common/kqp_tx.cpp
index 90ca0f9076..6e446d164a 100644
--- a/ydb/core/kqp/common/kqp_tx.cpp
+++ b/ydb/core/kqp/common/kqp_tx.cpp
@@ -40,10 +40,10 @@ NYql::TIssue GetLocksInvalidatedIssue(const TShardIdToTableInfo& shardIdToTableI
     TStringBuilder message;
     message << "Transaction locks invalidated.";
 
-    if (auto it = shardIdToTableInfo.find(shardId); it != std::end(shardIdToTableInfo)) {
+    if (auto tableInfoPtr = shardIdToTableInfo.GetPtr(shardId); tableInfoPtr) {
         message << " Tables: ";
         bool first = true;
-        for (const auto& path : it->second.Pathes) {
+        for (const auto& path : tableInfoPtr->Pathes) {
             if (!first) {
                 message << ", ";
                 first = false;
diff --git a/ydb/core/kqp/common/kqp_tx.h b/ydb/core/kqp/common/kqp_tx.h
index d5b2d7173b..23dc006957 100644
--- a/ydb/core/kqp/common/kqp_tx.h
+++ b/ydb/core/kqp/common/kqp_tx.h
@@ -123,10 +123,46 @@ private:
 
 struct TTableInfo {
     bool IsOlap = false;
-    THashSet<TString> Pathes;
+    THashSet<TStringBuf> Pathes;
 };
 
-using TShardIdToTableInfo = THashMap<ui64, TTableInfo>;
+
+class TShardIdToTableInfo {
+public:
+    const TTableInfo& Get(ui64 shardId) const {
+        const auto* result = GetPtr(shardId);
+        AFL_ENSURE(result);
+        return *result;
+    }
+
+    const TTableInfo* GetPtr(ui64 shardId) const {
+        auto it = ShardIdToInfo.find(shardId);
+        return it != std::end(ShardIdToInfo)
+            ? &it->second
+            : nullptr;
+    }
+
+    void Add(ui64 shardId, bool isOlap, const TString& path) {
+        const auto [stringsIter, _] = Strings.insert(path);
+        const TStringBuf pathBuf = *stringsIter;
+        auto infoIter = ShardIdToInfo.find(shardId);
+        if (infoIter != std::end(ShardIdToInfo)) {
+            AFL_ENSURE(infoIter->second.IsOlap == isOlap);
+            infoIter->second.Pathes.insert(pathBuf);
+        } else {
+            ShardIdToInfo.emplace(
+                shardId,
+                TTableInfo{
+                    .IsOlap = isOlap,
+                    .Pathes = {pathBuf},
+                });
+        }
+    }
+
+private:
+    THashMap<ui64, TTableInfo> ShardIdToInfo;
+    std::unordered_set<TString> Strings;// Pointers aren't invalidated.
+};
 using TShardIdToTableInfoPtr = std::shared_ptr<TShardIdToTableInfo>;
 
 class TKqpTransactionContext : public NYql::TKikimrTransactionContextBase  {
diff --git a/ydb/core/kqp/executer_actor/kqp_data_executer.cpp b/ydb/core/kqp/executer_actor/kqp_data_executer.cpp
index d139ae51e1..f129d4adfb 100644
--- a/ydb/core/kqp/executer_actor/kqp_data_executer.cpp
+++ b/ydb/core/kqp/executer_actor/kqp_data_executer.cpp
@@ -224,9 +224,7 @@ public:
 
                     const auto& task = TasksGraph.GetTask(taskId);
                     const auto& stageInfo = TasksGraph.GetStageInfo(task.StageId);
-                    auto& info = (*ShardIdToTableInfo)[lock.GetDataShard()];
-                    info.IsOlap = (stageInfo.Meta.TableKind == ETableKind::Olap);
-                    info.Pathes.insert(stageInfo.Meta.TablePath);
+                    ShardIdToTableInfo->Add(lock.GetDataShard(), stageInfo.Meta.TableKind == ETableKind::Olap, stageInfo.Meta.TablePath);
                 }
             } else if (data.GetData().template Is<NKikimrKqp::TEvKqpOutputActorResultInfo>()) {
                 NKikimrKqp::TEvKqpOutputActorResultInfo info;
@@ -236,9 +234,7 @@ public:
 
                     const auto& task = TasksGraph.GetTask(taskId);
                     const auto& stageInfo = TasksGraph.GetStageInfo(task.StageId);
-                    auto& info = (*ShardIdToTableInfo)[lock.GetDataShard()];
-                    info.IsOlap = (stageInfo.Meta.TableKind == ETableKind::Olap);
-                    info.Pathes.insert(stageInfo.Meta.TablePath);
+                    ShardIdToTableInfo->Add(lock.GetDataShard(), stageInfo.Meta.TableKind == ETableKind::Olap, stageInfo.Meta.TablePath);
                 }
             }
         };
@@ -1980,9 +1976,7 @@ private:
                 NYql::NDqProto::TDqTask* protoTask = ArenaSerializeTaskToProto(TasksGraph, task, true);
                 datashardTasks[task.Meta.ShardId].emplace_back(protoTask);
 
-                auto& info = (*ShardIdToTableInfo)[task.Meta.ShardId];
-                info.IsOlap = (stageInfo.Meta.TableKind == ETableKind::Olap);
-                info.Pathes.insert(stageInfo.Meta.TablePath);
+                ShardIdToTableInfo->Add(task.Meta.ShardId, stageInfo.Meta.TableKind == ETableKind::Olap, stageInfo.Meta.TablePath);
             } else if (stageInfo.Meta.IsSysView()) {
                 computeTasks.emplace_back(task.Id);
             } else {
@@ -2392,7 +2386,7 @@ private:
                         // Effects are only applied when all locks are valid
                         receivingShardsSet.insert(shardId);
 
-                        if (HtapTx && ShardIdToTableInfo->at(shardId).IsOlap) {
+                        if (HtapTx && ShardIdToTableInfo->Get(shardId).IsOlap) {
                             receivingColumnShardsSet.insert(shardId);
                         }
                     }