Better message for data materialization error. (#2841)

Author: spuchin

ydb/core/kqp/executer_actor/kqp_data_executer.cpp

@@ -279,8 +279,16 @@ class TKqpDataExecuter : public TKqpExecuterBase<TKqpDataExecuter, EExecType::Da
 
         auto resultSize = ResponseEv->GetByteSize();
         if (resultSize > (int)ReplySizeLimit) {
-            TString message = TStringBuilder() << "Query result size limit exceeded. ("
-                << resultSize << " > " << ReplySizeLimit << ")";
+            TString message;
+            if (ResponseEv->TxResults.size() == 1 && !ResponseEv->TxResults[0].QueryResultIndex.Defined()) {
+                message = TStringBuilder() << "Intermediate data materialization exceeded size limit"
+                    << " (" << resultSize << " > " << ReplySizeLimit << ")."
+                    << " This usually happens when trying to write large amounts of data or to perform lookup"
+                    << " by big collection of keys in single query. Consider using smaller batches of data.";
+            } else {
+                message = TStringBuilder() << "Query result size limit exceeded. ("
+                    << resultSize << " > " << ReplySizeLimit << ")";
+            }
 
             auto issue = YqlIssue({}, TIssuesIds::KIKIMR_RESULT_UNAVAILABLE, message);
             ReplyErrorAndDie(Ydb::StatusIds::PRECONDITION_FAILED, issue);

ydb/core/kqp/ut/query/kqp_limits_ut.cpp

@@ -1034,6 +1034,24 @@ Y_UNIT_TEST_SUITE(KqpLimits) {
             last = current;
         }
     }
+
+    Y_UNIT_TEST(QSReplySize) {
+        TKikimrRunner kikimr;
+        CreateLargeTable(kikimr, 100'000, 100, 1'000, 1'000, 1);
+
+        auto db = kikimr.GetQueryClient();
+
+        auto result = db.ExecuteQuery(R"(
+            UPSERT INTO KeyValue2
+            SELECT
+                KeyText AS Key,
+                DataText AS Value
+            FROM `/Root/LargeTable`;
+        )", NQuery::TTxControl::BeginTx().CommitTx()).ExtractValueSync();
+        result.GetIssues().PrintTo(Cerr);
+        UNIT_ASSERT_VALUES_EQUAL(result.GetStatus(), EStatus::PRECONDITION_FAILED);
+        UNIT_ASSERT(!to_lower(result.GetIssues().ToString()).Contains("query result"));
+    }
 }
 
 } // namespace NKqp