Remove support for non-scan read columns requests (#1240)

ydb/core/tx/datashard/datashard.cpp

@@ -145,8 +145,6 @@ TDataShard::TDataShard(const TActorId &tablet, TTabletStorageInfo *info)
     , DataTxProfileLogThresholdMs(0, 0, 86400000)
     , DataTxProfileBufferThresholdMs(0, 0, 86400000)
     , DataTxProfileBufferSize(0, 1000, 100)
-    , ReadColumnsScanEnabled(1, 0, 1)
-    , ReadColumnsScanInUserPool(0, 0, 1)
     , BackupReadAheadLo(0, 0, 64*1024*1024)
     , BackupReadAheadHi(0, 0, 128*1024*1024)
     , TtlReadAheadLo(0, 0, 64*1024*1024)
@@ -314,9 +312,6 @@ void TDataShard::IcbRegister() {
         appData->Icb->RegisterSharedControl(HighDataSizeReportThreshlodBytes, "DataShardControls.HighDataSizeReportThreshlodBytes");
         appData->Icb->RegisterSharedControl(HighDataSizeReportIntervalSeconds, "DataShardControls.HighDataSizeReportIntervalSeconds");
 
-        appData->Icb->RegisterSharedControl(ReadColumnsScanEnabled, "DataShardControls.ReadColumnsScanEnabled");
-        appData->Icb->RegisterSharedControl(ReadColumnsScanInUserPool, "DataShardControls.ReadColumnsScanInUserPool");
-
         appData->Icb->RegisterSharedControl(BackupReadAheadLo, "DataShardControls.BackupReadAheadLo");
         appData->Icb->RegisterSharedControl(BackupReadAheadHi, "DataShardControls.BackupReadAheadHi");
 

ydb/core/tx/datashard/datashard__read_columns.cpp

@@ -184,7 +184,6 @@ private:
     bool InclusiveTo;
     ui64 RowsLimit = 100000;
     ui64 BytesLimit = 1024*1024;
-    ui64 Restarts = 0;
     TRowVersion ReadVersion = TRowVersion::Max();
 
 public:
@@ -200,18 +199,7 @@ public:
 
     TTxType GetTxType() const override { return TXTYPE_READ_COLUMNS; }
 
-    bool Precharge(NTable::TDatabase& db, ui32 localTid, const TVector<NTable::TTag>& valueColumns) {
-        bool ready =  db.Precharge(localTid,
-                                   KeyFrom,
-                                   KeyTo,
-                                   valueColumns,
-                                   0,
-                                   RowsLimit, BytesLimit,
-                                   NTable::EDirection::Forward, ReadVersion);
-        return ready;
-    }
-
-    bool Execute(TTransactionContext& txc, const TActorContext& ctx) override {
+    bool Execute(TTransactionContext&, const TActorContext& ctx) override {
         // FIXME: we need to transform HEAD into some non-repeatable snapshot here
         if (!ReadVersion.IsMax() && Self->GetVolatileTxManager().HasVolatileTxsAtSnapshot(ReadVersion)) {
             Self->GetVolatileTxManager().AttachWaitingSnapshotEvent(
@@ -223,38 +211,13 @@ public:
 
         Result = new TEvDataShard::TEvReadColumnsResponse(Self->TabletID());
 
-        bool useScan = Self->ReadColumnsScanEnabled;
-
         if (Self->IsFollower()) {
-            NKikimrTxDataShard::TError::EKind status = NKikimrTxDataShard::TError::OK;
-            TString errMessage;
-
-            if (!Self->SyncSchemeOnFollower(txc, ctx, status, errMessage))
-                return false;
-
-            if (status != NKikimrTxDataShard::TError::OK) {
-                SetError(status, errMessage);
-                return true;
-            }
-
-            if (!ReadVersion.IsMax()) {
-                NIceDb::TNiceDb db(txc.DB);
-                TRowVersion lastCompleteTx;
-                if (!TDataShard::SysGetUi64(db, Schema::Sys_LastCompleteStep, lastCompleteTx.Step))
-                    return false;
-                if (!TDataShard::SysGetUi64(db, Schema::Sys_LastCompleteTx, lastCompleteTx.TxId))
-                    return false;
-
-                if (ReadVersion > lastCompleteTx) {
-                    SetError(NKikimrTxDataShard::TError::WRONG_SHARD_STATE,
-                             TStringBuilder() << "RO replica last version " << lastCompleteTx
-                             << " lags behind the requested snapshot " << ReadVersion
-                             << " shard " << Self->TabletID());
-                    return true;
-                }
-            }
+            // Note: this request is no longer supported, and it has never been used with followers
+            NKikimrTxDataShard::TError::EKind status = NKikimrTxDataShard::TError::WRONG_SHARD_STATE;
+            TString errMessage = "followers are not supported";
 
-            useScan = false;
+            SetError(status, errMessage);
+            return true;
         }
 
         LOG_DEBUG_S(ctx, NKikimrServices::TX_DATASHARD, Self->TabletID() << " Read columns: " << Ev->Get()->Record);
@@ -330,26 +293,6 @@ public:
 
         TSerializedCellVec toKeyCells;
 
-        if (!useScan) {
-            // Use histogram to limit the range for single request
-            const auto& sizeHistogram = tableInfo.Stats.DataStats.DataSizeHistogram;
-            auto histIt = LowerBound(sizeHistogram.begin(), sizeHistogram.end(), fromKeyCells,
-                       [&tableInfo] (const NTable::TBucket& bucket, const TSerializedCellVec& key) {
-                TSerializedCellVec bk(bucket.EndKey);
-                return CompareTypedCellVectors(
-                            bk.GetCells().data(), key.GetCells().data(),
-                            tableInfo.KeyColumnTypes.data(),
-                            bk.GetCells().size(), key.GetCells().size()) < 0;
-            });
-
-            if (histIt != sizeHistogram.end() && ++histIt != sizeHistogram.end()) {
-                toKeyCells.Parse(histIt->EndKey);
-                for (ui32 i = 0; i < toKeyCells.GetCells().size(); ++i) {
-                    KeyTo.push_back(TRawTypeValue(toKeyCells.GetCells()[i].AsRef(), tableInfo.KeyColumnTypes[i]));
-                }
-            }
-        }
-
         TVector<NTable::TTag> valueColumns;
         TVector<NScheme::TTypeInfo> valueColumnTypes;
         TVector<std::pair<TString, NScheme::TTypeInfo>> columns;
@@ -384,121 +327,35 @@ public:
 
         tableInfo.Stats.AccessTime = TAppData::TimeProvider->Now();
 
-        if (useScan) {
-            if (snapshotKey) {
-                if (!Self->GetSnapshotManager().AcquireReference(*snapshotKey)) {
-                    SetError(NKikimrTxDataShard::TError::SNAPSHOT_NOT_EXIST,
-                        TStringBuilder() << "Table id " << tableId << " has no snapshot at " << ReadVersion
-                             << " shard " << Self->TabletID() << (Self->IsFollower() ? " RO replica" : ""));
-                    return true;
-                }
-            }
-
-            auto* scan = new TReadColumnsScan(TKeyBoundary{fromKeyCells, InclusiveFrom},
-                                              TKeyBoundary{toKeyCells, InclusiveTo},
-                                              valueColumns, valueColumnTypes,
-                                              std::move(blockBuilder), RowsLimit, BytesLimit,
-                                              TKeyBoundary{tableInfo.Range.To, tableInfo.Range.ToInclusive},
-                                              Ev->Sender, ctx.SelfID,
-                                              snapshotKey,
-                                              tableInfo.Path,
-                                              Self->TabletID());
-            auto opts = TScanOptions()
-                    .SetResourceBroker("scan", 10)
-                    .SetSnapshotRowVersion(ReadVersion)
-                    .SetActorPoolId(Self->ReadColumnsScanInUserPool ? AppData(ctx)->UserPoolId : AppData(ctx)->BatchPoolId)
-                    .SetReadAhead(512*1024, 1024*1024)
-                    .SetReadPrio(TScanOptions::EReadPrio::Low);
-
-            ui64 cookie = -1; // Should be ignored
-            Self->QueueScan(localTableId, scan, cookie, opts);
-
-            Result.Destroy(); // Scan is now responsible for sending the result
-
-            return true;
-        }
-
-        // TODO: make sure KeyFrom and KeyTo properly reference non-inline cells data
-
-        if (!Precharge(txc.DB, localTableId, valueColumns))
-            return false;
-
-        size_t rows = 0;
-        size_t bytes = 0;
-        bool shardFinished = false;
-
-        {
-            NTable::TKeyRange iterRange;
-            iterRange.MinKey = KeyFrom;
-            iterRange.MinInclusive = InclusiveFrom;
-
-            auto iter = txc.DB.IterateRange(localTableId, iterRange, valueColumns, ReadVersion);
-
-            TString lastKeySerialized;
-            bool lastKeyInclusive = true;
-            while (iter->Next(NTable::ENext::All) == NTable::EReady::Data) {
-                TDbTupleRef rowKey = iter->GetKey();
-                lastKeySerialized = TSerializedCellVec::Serialize(rowKey.Cells());
-
-                // Compare current row with right boundary
-                int cmp = -1;// CompareTypedCellVectors(tuple.Columns, KeyTo.data(), tuple.Types, KeyTo.size());
-
-                if (cmp == 0 && KeyTo.size() < rowKey.ColumnCount) {
-                    cmp = -1;
-                }
-                if (InclusiveTo) {
-                    if (cmp > 0)
-                        break; // Stop iff greater(cmp > 0)
-                } else {
-                    if (cmp >= 0)
-                        break; // Stop iff equal(cmp == 0) or greater(cmp > 0)
-                }
-
-                // Skip erased row
-                if (iter->Row().GetRowState() == NTable::ERowOp::Erase) {
-                    continue;
-                }
-
-                TDbTupleRef rowValues = iter->GetValues();
-
-                blockBuilder->AddRow(rowKey, rowValues);
-
-                rows++;
-                bytes = blockBuilder->Bytes();
-
-                if (rows >= RowsLimit || bytes >= BytesLimit)
-                    break;
-            }
-
-            // We don't want to do many restarts if pages weren't precharged
-            // So we just return whatever we read so far and the client can request more rows
-            if (iter->Last() == NTable::EReady::Page && rows < 1000 && bytes < 100000 && Restarts < 1) {
-                ++Restarts;
-                return false;
-            }
-
-            if (iter->Last() == NTable::EReady::Gone) {
-                shardFinished = true;
-                lastKeySerialized = tableInfo.Range.To.GetBuffer();
-                lastKeyInclusive = tableInfo.Range.ToInclusive;
+        if (snapshotKey) {
+            if (!Self->GetSnapshotManager().AcquireReference(*snapshotKey)) {
+                SetError(NKikimrTxDataShard::TError::SNAPSHOT_NOT_EXIST,
+                    TStringBuilder() << "Table id " << tableId << " has no snapshot at " << ReadVersion
+                            << " shard " << Self->TabletID() << (Self->IsFollower() ? " RO replica" : ""));
+                return true;
             }
-
-            TString buffer = blockBuilder->Finish();
-            buffer.resize(blockBuilder->Bytes());
-
-            Result->Record.SetBlocks(buffer);
-            Result->Record.SetLastKey(lastKeySerialized);
-            Result->Record.SetLastKeyInclusive(lastKeyInclusive);
-            Result->Record.SetEndOfShard(shardFinished);
         }
 
-        Self->IncCounter(COUNTER_READ_COLUMNS_ROWS, rows);
-        Self->IncCounter(COUNTER_READ_COLUMNS_BYTES, bytes);
-
-        LOG_DEBUG_S(ctx, NKikimrServices::TX_DATASHARD, Self->TabletID()
-                    << " Read columns result for table [" << tableInfo.Path << "]: "
-                    << rows << " rows, " << bytes << " bytes (event size "
-                    << Result->Record.GetBlocks().size() << ") shardFinished: " << shardFinished);
+        auto* scan = new TReadColumnsScan(TKeyBoundary{fromKeyCells, InclusiveFrom},
+                                            TKeyBoundary{toKeyCells, InclusiveTo},
+                                            valueColumns, valueColumnTypes,
+                                            std::move(blockBuilder), RowsLimit, BytesLimit,
+                                            TKeyBoundary{tableInfo.Range.To, tableInfo.Range.ToInclusive},
+                                            Ev->Sender, ctx.SelfID,
+                                            snapshotKey,
+                                            tableInfo.Path,
+                                            Self->TabletID());
+        auto opts = TScanOptions()
+                .SetResourceBroker("scan", 10)
+                .SetSnapshotRowVersion(ReadVersion)
+                .SetActorPoolId(AppData(ctx)->BatchPoolId)
+                .SetReadAhead(512*1024, 1024*1024)
+                .SetReadPrio(TScanOptions::EReadPrio::Low);
+
+        ui64 cookie = -1; // Should be ignored
+        Self->QueueScan(localTableId, scan, cookie, opts);
+
+        Result.Destroy(); // Scan is now responsible for sending the result
 
         return true;
     }

ydb/core/tx/datashard/datashard_impl.h

@@ -2631,9 +2631,6 @@ private:
     TControlWrapper DataTxProfileBufferThresholdMs;
     TControlWrapper DataTxProfileBufferSize;
 
-    TControlWrapper ReadColumnsScanEnabled;
-    TControlWrapper ReadColumnsScanInUserPool;
-
     TControlWrapper BackupReadAheadLo;
     TControlWrapper BackupReadAheadHi;