/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cassandra.cql3.statements;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.NavigableSet;
import java.util.Set;
import java.util.function.BiFunction;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.HashMultiset;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import accord.utils.Invariants;

import org.apache.cassandra.auth.Permission;
import org.apache.cassandra.cql3.Attributes;
import org.apache.cassandra.cql3.CQLStatement;
import org.apache.cassandra.cql3.ColumnIdentifier;
import org.apache.cassandra.cql3.ColumnSpecification;
import org.apache.cassandra.cql3.FunctionContext;
import org.apache.cassandra.cql3.Operation;
import org.apache.cassandra.cql3.Operations;
import org.apache.cassandra.cql3.QualifiedName;
import org.apache.cassandra.cql3.QueryOptions;
import org.apache.cassandra.cql3.QueryProcessor;
import org.apache.cassandra.cql3.ResultSet;
import org.apache.cassandra.cql3.RowUpdateBuilder;
import org.apache.cassandra.cql3.RowUpdateBuilder.RegularRowUpdateBuilder;
import org.apache.cassandra.cql3.StatementSource;
import org.apache.cassandra.cql3.Validation;
import org.apache.cassandra.cql3.VariableSpecifications;
import org.apache.cassandra.cql3.WhereClause;
import org.apache.cassandra.cql3.conditions.ColumnCondition;
import org.apache.cassandra.cql3.conditions.ColumnConditions;
import org.apache.cassandra.cql3.conditions.Conditions;
import org.apache.cassandra.cql3.constraints.ConstraintViolationException;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.cql3.restrictions.StatementRestrictions;
import org.apache.cassandra.cql3.selection.ResultSetBuilder;
import org.apache.cassandra.cql3.selection.Selection;
import org.apache.cassandra.cql3.selection.Selection.Selectors;
import org.apache.cassandra.cql3.terms.Constants;
import org.apache.cassandra.cql3.transactions.ReferenceOperation;
import org.apache.cassandra.db.CBuilder;
import org.apache.cassandra.db.Clustering;
import org.apache.cassandra.db.ConsistencyLevel;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.db.IMutation;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.db.ReadCommand.PotentialTxnConflicts;
import org.apache.cassandra.db.ReadExecutionController;
import org.apache.cassandra.db.RegularAndStaticColumns;
import org.apache.cassandra.db.SinglePartitionReadCommand;
import org.apache.cassandra.db.SinglePartitionReadQuery;
import org.apache.cassandra.db.Slice;
import org.apache.cassandra.db.Slices;
import org.apache.cassandra.db.filter.ClusteringIndexFilter;
import org.apache.cassandra.db.filter.ClusteringIndexNamesFilter;
import org.apache.cassandra.db.filter.ClusteringIndexSliceFilter;
import org.apache.cassandra.db.filter.ColumnFilter;
import org.apache.cassandra.db.filter.DataLimits;
import org.apache.cassandra.db.filter.IndexHints;
import org.apache.cassandra.db.filter.RowFilter;
import org.apache.cassandra.db.guardrails.Guardrails;
import org.apache.cassandra.db.marshal.BooleanType;
import org.apache.cassandra.db.partitions.FilteredPartition;
import org.apache.cassandra.db.partitions.Partition;
import org.apache.cassandra.db.partitions.PartitionIterator;
import org.apache.cassandra.db.partitions.PartitionIterators;
import org.apache.cassandra.db.partitions.PartitionUpdate;
import org.apache.cassandra.db.rows.Row;
import org.apache.cassandra.db.rows.RowIterator;
import org.apache.cassandra.db.view.View;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.exceptions.InvalidRequestException;
import org.apache.cassandra.exceptions.RequestExecutionException;
import org.apache.cassandra.exceptions.RequestValidationException;
import org.apache.cassandra.exceptions.UnauthorizedException;
import org.apache.cassandra.locator.NetworkTopologyStrategy;
import org.apache.cassandra.locator.Replica;
import org.apache.cassandra.locator.ReplicaLayout;
import org.apache.cassandra.metrics.ClientRequestSizeMetrics;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.schema.Schema;
import org.apache.cassandra.schema.SchemaConstants;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.schema.ViewMetadata;
import org.apache.cassandra.service.ClientState;
import org.apache.cassandra.service.PreserveTimestamp;
import org.apache.cassandra.service.QueryState;
import org.apache.cassandra.service.StorageProxy;
import org.apache.cassandra.service.accord.api.PartitionKey;
import org.apache.cassandra.service.accord.serializers.TableMetadatasAndKeys.KeyCollector;
import org.apache.cassandra.service.accord.txn.TxnReferenceOperation;
import org.apache.cassandra.service.accord.txn.TxnReferenceOperations;
import org.apache.cassandra.service.accord.txn.TxnWrite;
import org.apache.cassandra.service.disk.usage.DiskUsageBroadcaster;
import org.apache.cassandra.service.paxos.Ballot;
import org.apache.cassandra.service.paxos.BallotGenerator;
import org.apache.cassandra.service.paxos.Commit.Proposal;
import org.apache.cassandra.tcm.ClusterMetadata;
import org.apache.cassandra.transport.Dispatcher;
import org.apache.cassandra.transport.messages.ResultMessage;
import org.apache.cassandra.triggers.TriggerExecutor;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.MD5Digest;

import static org.apache.cassandra.cql3.statements.RequestValidations.checkFalse;
import static org.apache.cassandra.cql3.statements.RequestValidations.checkNull;
import static org.apache.cassandra.service.paxos.Ballot.Flag.NONE;

/*
 * Abstract parent class of individual modifications, i.e. INSERT, UPDATE and DELETE.
 */
public abstract class ModificationStatement implements CQLStatement.SingleKeyspaceCqlStatement
{
    protected static final Logger logger = LoggerFactory.getLogger(ModificationStatement.class);

    private final static MD5Digest EMPTY_HASH = MD5Digest.wrap(new byte[] {});

    public static final String CUSTOM_EXPRESSIONS_NOT_ALLOWED =
        "Custom index expressions cannot be used in WHERE clauses for UPDATE or DELETE statements";

    public static final ColumnIdentifier CAS_RESULT_COLUMN = new ColumnIdentifier("[applied]", false);

    protected final StatementType type;

    protected final VariableSpecifications bindVariables;

    public final TableMetadata metadata;
    protected final Attributes attrs;

    protected final StatementRestrictions restrictions;

    private final Operations operations;

    private final boolean isReadRequired;

    private final RegularAndStaticColumns updatedColumns;

    protected final Conditions conditions;

    private final RegularAndStaticColumns conditionColumns;

    private final RegularAndStaticColumns requiresRead;
    /**
     * Used by {@link #forTxn()} to only compute a migrated copy of this statement for transactions
     */
    private ModificationStatement txnStmt;

    private final List<Function> functions;

    public final StatementSource source;

    public ModificationStatement(StatementType type,
                                 VariableSpecifications bindVariables,
                                 TableMetadata metadata,
                                 Operations operations,
                                 StatementRestrictions restrictions,
                                 Conditions conditions,
                                 Attributes attrs,
                                 StatementSource source)
    {
        this.type = type;
        this.bindVariables = bindVariables;
        this.metadata = metadata;
        this.restrictions = restrictions;
        this.operations = operations;
        this.conditions = conditions;
        this.attrs = attrs;
        this.source = source;

        if (!conditions.isEmpty())
        {
            checkFalse(metadata.isCounter(), "Conditional updates are not supported on counter tables");
            checkFalse(attrs.isTimestampSet(), "Cannot provide custom timestamp for conditional updates");
        }

        RegularAndStaticColumns.Builder conditionColumnsBuilder = RegularAndStaticColumns.builder();
        Iterable<ColumnMetadata> columns = conditions.getColumns();
        if (columns != null)
            conditionColumnsBuilder.addAll(columns);

        RegularAndStaticColumns.Builder updatedColumnsBuilder = RegularAndStaticColumns.builder();
        RegularAndStaticColumns.Builder requiresReadBuilder = RegularAndStaticColumns.builder();
        for (Operation operation : operations)
        {
            updatedColumnsBuilder.add(operation.column);
            // If the operation requires a read-before-write and we're doing a conditional read, we want to read
            // the affected column as part of the read-for-conditions paxos phase (see #7499).
            if (operation.requiresRead())
            {
                conditionColumnsBuilder.add(operation.column);
                requiresReadBuilder.add(operation.column);
            }
        }
        for (ReferenceOperation operation : operations.allSubstitutions())
        {
            ColumnMetadata receiver = operation.getReceiver();
            updatedColumnsBuilder.add(receiver);
            // If the operation requires a read-before-write, make sure its receiver is selected by the auto-read the
            // transaction creates during update creation. (see createSelectForTxn())
            if (operation.requiresRead())
                requiresReadBuilder.add(receiver);
        }

        RegularAndStaticColumns modifiedColumns = updatedColumnsBuilder.build();

        // Compact tables have not row marker. So if we don't actually update any particular column,
        // this means that we're only updating the PK, which we allow if only those were declared in
        // the definition. In that case however, we do went to write the compactValueColumn (since again
        // we can't use a "row marker") so add it automatically.
        if (metadata.isCompactTable() && modifiedColumns.isEmpty() && updatesRegularRows())
            modifiedColumns = metadata.regularAndStaticColumns();

        this.updatedColumns = modifiedColumns;

        if (!this.metadata.notNullColumns.isEmpty())
        {
            if (this.type.isInsertOrUpdate())
            {
                for (ColumnMetadata notNullColumn : this.metadata.notNullColumns)
                {
                    if (!updatedColumns.contains(notNullColumn))
                        throw RequestValidations.invalidRequest(String.format("Column '%s' has to be specified as part of this query.",
                                                                              notNullColumn.name));
                }
            }
            else if (this.type.isDelete())
            {
                for (ColumnMetadata notNullColumn : this.metadata.notNullColumns)
                {
                    if (updatedColumns.contains(notNullColumn))
                        throw RequestValidations.invalidRequest(String.format("Column '%s' can not be set to null.",
                                                                              notNullColumn.name));
                }
            }
        }

        this.conditionColumns = conditionColumnsBuilder.build();
        this.requiresRead = requiresReadBuilder.build();
        this.functions = findAllFunctions();
        this.isReadRequired = operations.requiresRead();
    }

    @Override
    public ImmutableList<ColumnSpecification> getBindVariables()
    {
        return bindVariables.getImmutableBindVariables();
    }

    @Override
    public short[] getPartitionKeyBindVariableIndexes()
    {
        return bindVariables.getPartitionKeyBindVariableIndexes(metadata, attrs);
    }

    @Override
    public Iterable<Function> getFunctions()
    {
        return functions;
    }

    private List<Function> findAllFunctions()
    {
        List<Function> functions = new ArrayList<>();
        addFunctionsTo(functions);
        if (functions.isEmpty())
        {
            functions = Collections.emptyList(); // to avoid a new Iterator object creation during each authorization
        }

        return functions;
    }

    @Override
    public boolean eligibleAsPreparedStatement()
    {
        return true;
    }

    public void addFunctionsTo(List<Function> functions)
    {
        attrs.addFunctionsTo(functions);
        restrictions.addFunctionsTo(functions);
        operations.addFunctionsTo(functions);
        conditions.addFunctionsTo(functions);
    }

    public TableMetadata metadata()
    {
        return metadata;
    }

    /*
     * May be used by QueryHandler implementations
     */
    public StatementRestrictions getRestrictions()
    {
        return restrictions;
    }

    public abstract void addUpdateForKey(PartitionUpdate.Builder updateBuilder, Clustering<?> clustering, RowUpdateBuilder builder);

    public abstract void addUpdateForKey(PartitionUpdate.Builder updateBuilder, Slice slice, RowUpdateBuilder builder);

    @Override
    public String keyspace()
    {
        return metadata.keyspace;
    }

    public String table()
    {
        return metadata.name;
    }

    public boolean isCounter()
    {
        return metadata().isCounter();
    }

    public boolean isView()
    {
        return metadata().isView();
    }

    public boolean isVirtual()
    {
        return metadata().isVirtual();
    }

    public long getTimestamp(long now, FunctionContext context) throws InvalidRequestException
    {
        return attrs.getTimestamp(now, context);
    }

    public boolean isTimestampSet()
    {
        return attrs.isTimestampSet();
    }

    public int getTimeToLive(FunctionContext context) throws InvalidRequestException
    {
        return attrs.getTimeToLive(context, metadata);
    }

    @Override
    public void authorize(ClientState state) throws InvalidRequestException, UnauthorizedException
    {
        state.ensureTablePermission(metadata, Permission.MODIFY);

        // CAS updates can be used to simulate a SELECT query, so should require Permission.SELECT as well.
        if (hasConditions())
            state.ensureTablePermission(metadata, Permission.SELECT);

        // MV updates need to get the current state from the table, and might update the views
        // Require Permission.SELECT on the base table, and Permission.MODIFY on the views
        Iterator<ViewMetadata> views = View.findAll(keyspace(), table()).iterator();
        if (views.hasNext())
        {
            state.ensureTablePermission(metadata, Permission.SELECT);
            do
            {
                state.ensureTablePermission(views.next().metadata, Permission.MODIFY);
            } while (views.hasNext());
        }

        for (Function function : getFunctions())
            state.ensurePermission(Permission.EXECUTE, function);
    }

    public void validate(ClientState state) throws InvalidRequestException
    {
        checkFalse(hasConditions() && attrs.isTimestampSet(), "Cannot provide custom timestamp for conditional updates");
        checkFalse(isCounter() && attrs.isTimestampSet(), "Cannot provide custom timestamp for counter updates");
        checkFalse(isCounter() && attrs.isTimeToLiveSet(), "Cannot provide custom TTL for counter updates");
        checkFalse(isView(), "Cannot directly modify a materialized view");
        checkFalse(isVirtual() && attrs.isTimestampSet(), "Custom timestamp is not supported by virtual tables");
        checkFalse(isVirtual() && attrs.isTimeToLiveSet(), "Expiring columns are not supported by virtual tables");
        checkFalse(isVirtual() && hasConditions(), "Conditional updates are not supported by virtual tables");

        if (attrs.isTimestampSet())
            Guardrails.userTimestampsEnabled.ensureEnabled(state);
    }

    public void validateDiskUsage(QueryOptions options, ClientState state)
    {

        if (Guardrails.diskUsageKeyspaceWideProtection.enabled(state) &&
            Guardrails.instance.getDataDiskUsageKeyspaceWideProtectionEnabled() &&
            DiskUsageBroadcaster.instance.hasStuffedOrFullNode())
        {
            Keyspace keyspace = Keyspace.open(keyspace());
            // If the keyspace is using NetworkTopologyStrategy then we can check each datacenter on which
            // the keyspace is replicated.
            if (keyspace.getMetadata().replicationStrategy instanceof NetworkTopologyStrategy)
            {
                for (String datacenter : ((NetworkTopologyStrategy) keyspace.getMetadata().replicationStrategy).getDatacenters())
                {
                    Guardrails.diskUsageKeyspaceWideProtection.guard(datacenter, state);
                }
            }
            // Otherwise, if we are using SimpleStrategy then we have to check if any datacenter contains a full node.
            else
            {
                for (String datacenter : ClusterMetadata.current().directory.knownDatacenters())
                {
                    Guardrails.diskUsageKeyspaceWideProtection.guard(datacenter, state);
                }
            }
        }
        else if (Guardrails.replicaDiskUsage.enabled(state) && DiskUsageBroadcaster.instance.hasStuffedOrFullNode())
        {
            Keyspace keyspace = Keyspace.open(keyspace());
            for (ByteBuffer key : buildPartitionKeyNames(options, state))
            {
                Token token = metadata().partitioner.getToken(key);
                for (Replica replica : ReplicaLayout.forTokenWriteLiveAndDown(keyspace, token).all())
                {
                    Guardrails.replicaDiskUsage.guard(replica.endpoint(), state);
                }
            }
        }
    }

    public void validateTimestamp(QueryState queryState, FunctionContext context)
    {
        if (!isTimestampSet())
            return;

        long ts = attrs.getTimestamp(context.options().getTimestamp(queryState), context);
        Guardrails.maximumAllowableTimestamp.guard(ts, table(), false, queryState.getClientState());
        Guardrails.minimumAllowableTimestamp.guard(ts, table(), false, queryState.getClientState());
    }

    public RegularAndStaticColumns updatedColumns()
    {
        return updatedColumns;
    }

    public RegularAndStaticColumns conditionColumns()
    {
        return conditionColumns;
    }

    public boolean updatesRegularRows()
    {
        // We're updating regular rows if all the clustering columns are provided.
        // Note that the only case where we're allowed not to provide clustering
        // columns is if we set some static columns, and in that case no clustering
        // columns should be given. So in practice, it's enough to check if we have
        // either the table has no clustering or if it has at least one of them set.
        return metadata().clusteringColumns().isEmpty() || restrictions.hasClusteringColumnsRestrictions();
    }

    public boolean updatesStaticRow()
    {
        return operations.appliesToStaticColumns();
    }

    public List<Operation> getRegularOperations()
    {
        return operations.regularOperations();
    }

    public List<Operation> getStaticOperations()
    {
        return operations.staticOperations();
    }

    public Collection<ReferenceOperation> allReferenceOperations()
    {
        return operations.allSubstitutions();
    }

    public Iterable<ColumnMetadata> getColumnsWithConditions()
    {
         return conditions.getColumns();
    }

    public boolean hasIfNotExistCondition()
    {
        return conditions.isIfNotExists();
    }

    public boolean hasIfExistCondition()
    {
        return conditions.isIfExists();
    }

    public List<ByteBuffer> buildPartitionKeyNames(QueryOptions options, ClientState state)
    throws InvalidRequestException
    {
        List<ByteBuffer> partitionKeys = restrictions.getPartitionKeys(options, state);
        for (int i = 0; i < partitionKeys.size(); i++)
            QueryProcessor.validateKey(partitionKeys.get(i));

        return partitionKeys;
    }

    public NavigableSet<Clustering<?>> createClustering(QueryOptions options, ClientState state)
    throws InvalidRequestException
    {
        if (appliesOnlyToStaticColumns() && !restrictions.hasClusteringColumnsRestrictions())
            return FBUtilities.singleton(CBuilder.STATIC_BUILDER.build(), metadata().comparator);

        return restrictions.getClusteringColumns(options, state);
    }

    /**
     * Checks that the modification only apply to static columns.
     * @return <code>true</code> if the modification only apply to static columns, <code>false</code> otherwise.
     */
    private boolean appliesOnlyToStaticColumns()
    {
        return appliesOnlyToStaticColumns(operations, conditions);
    }

    /**
     * Checks that the specified operations and conditions only apply to static columns.
     * @return <code>true</code> if the specified operations and conditions only apply to static columns,
     * <code>false</code> otherwise.
     */
    public static boolean appliesOnlyToStaticColumns(Operations operation, Conditions conditions)
    {
        return !operation.appliesToRegularColumns() && !conditions.appliesToRegularColumns()
                && (operation.appliesToStaticColumns() || conditions.appliesToStaticColumns());
    }

    public boolean requiresRead()
    {
        // A subset of operations require a read before write:
        // * Setting list element by index
        // * Deleting list element by index
        // * Deleting list element by value
        // * Performing addition on a StringType (i.e. concatenation, only supported for CAS operations)
        // * Performing addition on a NumberType, again only supported for CAS operations.
        return isReadRequired;
    }

    private <F> Map<DecoratedKey, Partition> readRequiredLists(Collection<ByteBuffer> partitionKeys,
                                                           java.util.function.Function<F, ClusteringIndexFilter> filterBuilder,
                                                           F filterArg,
                                                           DataLimits limits,
                                                           boolean local,
                                                           ConsistencyLevel cl,
                                                           long nowInSeconds,
                                                           Dispatcher.RequestTime requestTime)
    {
        if (!requiresRead())
            return null;

        try
        {
            cl.validateForRead();
        }
        catch (InvalidRequestException e)
        {
            throw new InvalidRequestException(String.format("Write operation require a read but consistency %s is not supported on reads", cl));
        }

        List<SinglePartitionReadCommand> commands = new ArrayList<>(partitionKeys.size());
        for (ByteBuffer key : partitionKeys)
            commands.add(SinglePartitionReadCommand.create(metadata(),
                                                           nowInSeconds,
                                                           ColumnFilter.selection(this.requiresRead),
                                                           RowFilter.none(),
                                                           limits,
                                                           metadata().partitioner.decorateKey(key),
                                                           filterBuilder.apply(filterArg)));

        SinglePartitionReadCommand.Group group = SinglePartitionReadCommand.Group.create(commands, DataLimits.NONE);

        if (local)
        {
            try (ReadExecutionController executionController = group.executionController();
                 PartitionIterator iter = group.executeInternal(executionController))
            {
                return asMaterializedMap(iter);
            }
        }

        try (PartitionIterator iter = group.execute(cl, null, requestTime))
        {
            return asMaterializedMap(iter);
        }
    }

    private Map<DecoratedKey, Partition> asMaterializedMap(PartitionIterator iterator)
    {
        Map<DecoratedKey, Partition> map = new HashMap<>();
        while (iterator.hasNext())
        {
            try (RowIterator partition = iterator.next())
            {
                map.put(partition.partitionKey(), FilteredPartition.create(partition));
            }
        }
        return map;
    }

    public boolean hasConditions()
    {
        return !conditions.isEmpty();
    }

    public boolean hasSlices()
    {
        return type.allowClusteringColumnSlices()
               && getRestrictions().hasClusteringColumnsRestrictions()
               && getRestrictions().isColumnRange();
    }

    public ResultMessage execute(QueryState queryState, QueryOptions options, Dispatcher.RequestTime requestTime)
    throws RequestExecutionException, RequestValidationException
    {
        if (options.getConsistency() == null)
            throw new InvalidRequestException("Invalid empty consistency level");

        if (Guardrails.writeConsistencyLevels.enabled(queryState.getClientState())) // to avoid EnumSet allocation
            Guardrails.writeConsistencyLevels.guard(EnumSet.of(options.getConsistency(), options.getSerialConsistency()),
                                                    queryState.getClientState());

        return hasConditions()
             ? executeWithCondition(queryState, options, requestTime)
             : executeWithoutCondition(queryState, options, requestTime);
    }

    private ResultMessage executeWithoutCondition(QueryState queryState, QueryOptions options, Dispatcher.RequestTime requestTime)
    throws RequestExecutionException, RequestValidationException
    {
        if (isVirtual())
            return executeInternalWithoutCondition(queryState, options, requestTime);

        ConsistencyLevel cl = options.getConsistency();
        if (isCounter())
            cl.validateCounterForWrite(metadata());
        else
            cl.validateForWrite();

        validateDiskUsage(options, queryState.getClientState());
        validateTimestamp(queryState, options);

        List<? extends IMutation> mutations =
            getMutations(queryState.getClientState(),
                         options,
                         false,
                         options.getTimestamp(queryState),
                         options.getNowInSeconds(queryState),
                         requestTime
            );
        if (!mutations.isEmpty())
        {
            StorageProxy.mutateWithTriggers(mutations, cl, false, requestTime, attrs.isTimestampSet() ? PreserveTimestamp.yes : PreserveTimestamp.no);

            if (!SchemaConstants.isSystemKeyspace(metadata.keyspace))
                ClientRequestSizeMetrics.recordRowAndColumnCountMetrics(mutations);
        }

        return null;
    }

    private ResultMessage executeWithCondition(QueryState queryState, QueryOptions options, Dispatcher.RequestTime requestTime)
    {
        CQL3CasRequest request = makeCasRequest(queryState, options, requestTime);

        try (RowIterator result = StorageProxy.cas(keyspace(),
                                                   table(),
                                                   request.key,
                                                   request,
                                                   options.getSerialConsistency(),
                                                   options.getConsistency(),
                                                   queryState.getClientState(),
                                                   options.getNowInSeconds(queryState),
                                                   requestTime))
        {
            return new ResultMessage.Rows(buildCasResultSet(result, queryState, options));
        }
    }

    private CQL3CasRequest makeCasRequest(QueryState queryState, QueryOptions options, Dispatcher.RequestTime requestTime)
    {
        ClientState clientState = queryState.getClientState();
        List<ByteBuffer> keys = buildPartitionKeyNames(options, clientState);
        // We don't support IN for CAS operation so far
        checkFalse(restrictions.keyIsInRelation(),
                   "IN on the partition key is not supported with conditional %s",
                   type.isUpdate()? "updates" : "deletions");

        DecoratedKey key = metadata().partitioner.decorateKey(keys.get(0));
        long timestamp = options.getTimestamp(queryState);
        long nowInSeconds = options.getNowInSeconds(queryState);

        checkFalse(restrictions.clusteringKeyRestrictionsHasIN(),
                   "IN on the clustering key columns is not supported with conditional %s",
                    type.isUpdate()? "updates" : "deletions");

        Clustering<?> clustering = Iterables.getOnlyElement(createClustering(options, clientState));
        CQL3CasRequest request = new CQL3CasRequest(metadata(), key, conditionColumns(), updatesRegularRows(), updatesStaticRow(), requestTime);

        addConditions(clustering, request, options);
        request.addRowUpdate(clustering, this, options, timestamp, nowInSeconds);

        return request;
    }

    public void addConditions(Clustering<?> clustering, CQL3CasRequest request, QueryOptions options) throws InvalidRequestException
    {
        conditions.addConditionsTo(request, clustering, options);
    }

    private static ResultSet.ResultMetadata buildCASSuccessMetadata(String ksName, String cfName)
    {
        List<ColumnSpecification> specs = new ArrayList<>();
        specs.add(casResultColumnSpecification(ksName, cfName));

        return new ResultSet.ResultMetadata(EMPTY_HASH, specs);
    }

    private static ColumnSpecification casResultColumnSpecification(String ksName, String cfName)
    {
        return new ColumnSpecification(ksName, cfName, CAS_RESULT_COLUMN, BooleanType.instance);
    }

    private ResultSet buildCasResultSet(RowIterator partition, QueryState state, QueryOptions options)
    {
        return buildCasResultSet(keyspace(), table(), partition, getColumnsWithConditions(), false, state, options);
    }

    static ResultSet buildCasResultSet(String ksName,
                                       String tableName,
                                       RowIterator partition,
                                       Iterable<ColumnMetadata> columnsWithConditions,
                                       boolean isBatch,
                                       QueryState state,
                                       QueryOptions options)
    {
        boolean success = partition == null;

        ResultSet.ResultMetadata metadata = buildCASSuccessMetadata(ksName, tableName);
        List<List<byte[]>> rows = Collections.singletonList(
            Collections.singletonList(
                ByteBufferUtil.getArrayUnsafeNullable(BooleanType.instance.decompose(success))
            )
        );

        ResultSet rs = new ResultSet(metadata, rows);
        return success ? rs : merge(rs, buildCasFailureResultSet(partition, columnsWithConditions, isBatch, options, options.getNowInSeconds(state)));
    }

    private static ResultSet merge(ResultSet left, ResultSet right)
    {
        if (left.size() == 0)
            return right;
        else if (right.size() == 0)
            return left;

        assert left.size() == 1;
        int size = left.metadata.names.size() + right.metadata.names.size();
        List<ColumnSpecification> specs = new ArrayList<>(size);
        specs.addAll(left.metadata.names);
        specs.addAll(right.metadata.names);
        List<List<byte[]>> rows = new ArrayList<>(right.size());
        for (int i = 0; i < right.size(); i++)
        {
            List<byte[]> row = new ArrayList<>(size);
            row.addAll(left.rows.get(0));
            row.addAll(right.rows.get(i));
            rows.add(row);
        }
        return new ResultSet(new ResultSet.ResultMetadata(EMPTY_HASH, specs), rows);
    }

    private static ResultSet buildCasFailureResultSet(RowIterator partition,
                                                      Iterable<ColumnMetadata> columnsWithConditions,
                                                      boolean isBatch,
                                                      QueryOptions options,
                                                      long nowInSeconds)
    {
        TableMetadata metadata = partition.metadata();
        Selection selection;
        if (columnsWithConditions == null)
        {
            selection = Selection.wildcard(metadata, false, false);
        }
        else
        {
            // We can have multiple conditions on the same columns (for collections) so use a set
            // to avoid duplicate, but preserve the order just to it follows the order of IF in the query in general
            Set<ColumnMetadata> defs = new LinkedHashSet<>();
            // Adding the partition key for batches to disambiguate if the conditions span multipe rows (we don't add them outside
            // of batches for compatibility sakes).
            if (isBatch)
                Iterables.addAll(defs, metadata.primaryKeyColumns());
            Iterables.addAll(defs, columnsWithConditions);
            selection = Selection.forColumns(metadata, new ArrayList<>(defs), false);
        }

        Selectors selectors = selection.newSelectors(options);
        ResultSetBuilder builder = new ResultSetBuilder(selection.getResultMetadata(), options, selectors, false);
        SelectStatement.forSelection(metadata, selection)
                       .processPartition(partition, options, builder, nowInSeconds);

        return builder.build();
    }

    public ResultMessage executeLocally(QueryState queryState, QueryOptions options) throws RequestValidationException, RequestExecutionException
    {
        return hasConditions()
               ? executeInternalWithCondition(queryState, options, Dispatcher.RequestTime.forImmediateExecution())
               : executeInternalWithoutCondition(queryState, options, Dispatcher.RequestTime.forImmediateExecution());
    }

    public ResultMessage executeInternalWithoutCondition(QueryState queryState, QueryOptions options, Dispatcher.RequestTime requestTime)
    throws RequestValidationException, RequestExecutionException
    {
        long timestamp = options.getTimestamp(queryState);
        long nowInSeconds = options.getNowInSeconds(queryState);
        for (IMutation mutation : getMutations(queryState.getClientState(), options, true, timestamp, nowInSeconds, requestTime))
            mutation.apply();
        return null;
    }

    public ResultMessage executeInternalWithCondition(QueryState state, QueryOptions options, Dispatcher.RequestTime requestTime)
    {
        CQL3CasRequest request = makeCasRequest(state, options, requestTime);

        try (RowIterator result = casInternal(state.getClientState(), request, options.getTimestamp(state), options.getNowInSeconds(state)))
        {
            return new ResultMessage.Rows(buildCasResultSet(result, state, options));
        }
    }

    static RowIterator casInternal(ClientState state, CQL3CasRequest request, long timestamp, long nowInSeconds)
    {
        Ballot ballot = BallotGenerator.Global.atUnixMicros(timestamp, NONE);

        SinglePartitionReadQuery readCommand = request.readCommand(nowInSeconds);
        FilteredPartition current;
        try (ReadExecutionController executionController = readCommand.executionController();
             PartitionIterator iter = readCommand.executeInternal(executionController))
        {
            current = FilteredPartition.create(PartitionIterators.getOnlyElement(iter, readCommand));
        }

        if (!request.appliesTo(current))
            return current.rowIterator(false);

        PartitionUpdate updates = request.makeUpdates(current, state, ballot);
        updates = TriggerExecutor.instance.execute(updates);

        Proposal proposal = Proposal.of(ballot, updates);
        proposal.makeMutation().apply();
        return null;
    }

    /**
     * Convert statement into a list of mutations to apply on the server
     *
     * @param state the client state
     * @param options value for prepared statement markers
     * @param local if true, any requests (for collections) performed by getMutation should be done locally only.
     * @param timestamp the current timestamp in microseconds to use if no timestamp is user provided.
     *
     * @return list of the mutations
     */
    public List<? extends IMutation> getMutations(ClientState state,
                                                  QueryOptions options,
                                                  boolean local,
                                                  long timestamp,
                                                  long nowInSeconds,
                                                  Dispatcher.RequestTime requestTime)
    {
        List<ByteBuffer> keys = buildPartitionKeyNames(options, state);

        if (keys.size() == 1)
        {
            SingleTableSinglePartitionUpdatesCollector collector = new SingleTableSinglePartitionUpdatesCollector(metadata, updatedColumns);
            addUpdates(collector, keys, state, options, local, timestamp, nowInSeconds, requestTime);
            // local means this is test or internal things that are bypassing distributed system modification/checks
            return collector.toMutations(state, local ? PotentialTxnConflicts.ALLOW : PotentialTxnConflicts.DISALLOW);
        }
        else
        {
            HashMultiset<ByteBuffer> perPartitionKeyCounts = HashMultiset.create(keys);
            SingleTableUpdatesCollector collector = new SingleTableUpdatesCollector(metadata, updatedColumns, perPartitionKeyCounts);
            addUpdates(collector, keys, state, options, local, timestamp, nowInSeconds, requestTime);
            // local means this is test or internal things that are bypassing distributed system modification/checks
            return collector.toMutations(state, local ? PotentialTxnConflicts.ALLOW : PotentialTxnConflicts.DISALLOW);
        }
    }

    public List<PartitionUpdate> getTxnUpdate(ClientState state, QueryOptions options)
    {
        List<? extends IMutation> mutations = getMutations(state, options, false, 0, 0, new Dispatcher.RequestTime(0, 0));
        if (mutations.isEmpty())
            return Collections.emptyList();
        List<PartitionUpdate> updates = new ArrayList<>(mutations.size());
        for (IMutation m : mutations)
            updates.addAll(m.getPartitionUpdates());
        return updates;
    }

    private static List<TxnReferenceOperation> getTxnReferenceOps(List<ReferenceOperation> operations, QueryOptions options)
    {
        if (operations.isEmpty())
            return Collections.emptyList();

        List<TxnReferenceOperation> result = new ArrayList<>(operations.size());
        for (ReferenceOperation operation : operations)
            result.add(operation.bindAndGet(options));
        return result;
    }

    public TxnReferenceOperations getTxnReferenceOps(QueryOptions options, ClientState state)
    {
        List<TxnReferenceOperation> regularOps = getTxnReferenceOps(operations.regularSubstitutions(), options);
        List<TxnReferenceOperation> staticOps = getTxnReferenceOps(operations.staticSubstitutions(), options);
        List<Clustering<?>> clusterings = txnClusterings(options, state);
        return new TxnReferenceOperations(metadata, clusterings, regularOps, staticOps);
    }

    private List<Clustering<?>> txnClusterings(QueryOptions options, ClientState state)
    {
        if (restrictions.hasAllPrimaryKeyColumnsRestrictedByEqualities())
            return new ArrayList<>(restrictions.getClusteringColumns(options, state));
        // Range/Partition delete, static only
        return Collections.emptyList();
    }

    public ModificationStatement forTxn()
    {
        if (requiresRead.isEmpty()) return this;
        ModificationStatement migrated = txnStmt;
        if (migrated == null)
        {
            synchronized (requiresRead)
            {
                migrated = txnStmt;
                if (migrated == null)
                    txnStmt = migrated = withOperations(operations.forTxn(metadata));
            }
        }
        return migrated;
    }

    protected abstract ModificationStatement withOperations(Operations operations);

    @VisibleForTesting
    public List<ReferenceOperation> getSubstitutions()
    {
        return operations.allSubstitutions();
    }

    public List<TxnWrite.Fragment> getTxnWriteFragment(int index, ClientState state, QueryOptions options, PartitionKey partitionKey)
    {
        return getTxnWriteFragment(index, state, options, baseUpdate -> {
            Invariants.require(baseUpdate.partitionKey().equals(partitionKey.partitionKey()), "PartitionUpdate generated a partition key different than the one expected");
            return partitionKey;
        });
    }

    public List<TxnWrite.Fragment> getTxnWriteFragment(int index, ClientState state, QueryOptions options, KeyCollector keyCollector)
    {
        return getTxnWriteFragment(index, state, options, baseUpdate -> keyCollector.collect(baseUpdate.metadata(), baseUpdate.partitionKey()));
    }

    private List<TxnWrite.Fragment> getTxnWriteFragment(int index, ClientState state, QueryOptions options, java.util.function.Function<PartitionUpdate, PartitionKey> keyCollector)
    {
        List<PartitionUpdate> baseUpdates = getTxnUpdate(state, options);
        TxnReferenceOperations referenceOps = getTxnReferenceOps(options, state);
        long timestamp = attrs.isTimestampSet() ? attrs.getTimestamp(TxnWrite.NO_TIMESTAMP, options) : TxnWrite.NO_TIMESTAMP;
        if (baseUpdates.size() == 1)
        {
            PartitionUpdate baseUpdate = baseUpdates.get(0);
            return Collections.singletonList(new TxnWrite.Fragment(keyCollector.apply(baseUpdate), index, baseUpdate, referenceOps, timestamp));
        }
        List<TxnWrite.Fragment> fragments = new ArrayList<>(baseUpdates.size());
        for (PartitionUpdate baseUpdate : baseUpdates)
            fragments.add(new TxnWrite.Fragment(keyCollector.apply(baseUpdate), index, baseUpdate, referenceOps, timestamp));
        return fragments;
    }

    public <V> void forEachRowKey(List<TxnWrite.Fragment> writeFragments, Map<? super RowKey, V> map, V param, BiFunction<V, V, V> merge)
    {
        for (int i = 0, size = writeFragments.size() ; i < size ; i++)
        {
            TxnWrite.Fragment writeFragment = writeFragments.get(i);
            DecoratedKey key = writeFragment.key.partitionKey();
            for (Row row : writeFragment.baseUpdate)
                map.merge(new RowKey(key, row.clustering()), param, merge);
        }
    }

    public <V> void forEachPartitionKey(List<TxnWrite.Fragment> writeFragments, Map<? super DecoratedKey, V> map, V param, BiFunction<V, V, V> mergeFunction)
    {
        for (int i = 0, size = writeFragments.size(); i < size; i++)
        {
            TxnWrite.Fragment writeFragment = writeFragments.get(i);
            DecoratedKey key = writeFragment.key.partitionKey();
            map.merge(key, param, mergeFunction);
        }
    }

    public static class RowKey
    {
        public final DecoratedKey key;
        public final Clustering<?> clustering;

        public RowKey(DecoratedKey key, Clustering<?> clustering)
        {
            this.key = key;
            this.clustering = clustering;
        }

        public DecoratedKey partitionKey()
        {
            return key;
        }

        public Clustering<?> clustering()
        {
            return clustering;
        }

        @Override
        public boolean equals(Object other)
        {
            if (other == this)
                return true;
            if (!(other instanceof RowKey))
                return false;

            RowKey that = (RowKey) other;
            return this.partitionKey().equals(that.partitionKey()) && this.clustering().equals(that.clustering());
        }

        @Override
        public int hashCode()
        {
            return partitionKey().hashCode() * 31 + clustering().hashCode();
        }
    }

    final void addUpdates(UpdatesCollector collector,
                          List<ByteBuffer> keys,
                          ClientState state,
                          QueryOptions options,
                          boolean local,
                          long timestamp,
                          long nowInSeconds,
                          Dispatcher.RequestTime requestTime)
    {
        if (hasSlices())
        {
            Slices slices = createSlices(options);

            // If all the ranges were invalid we do not need to do anything.
            if (slices.isEmpty())
                return;

            RowUpdateBuilder params = makeUpdateParameters(keys,
                                                           (slicesToFilter) -> new ClusteringIndexSliceFilter(slicesToFilter, false),
                                                           slices,
                                                           state,
                                                           options,
                                                           DataLimits.NONE,
                                                           local,
                                                           timestamp,
                                                           nowInSeconds,
                                                           requestTime
            );
            for (ByteBuffer key : keys)
            {
                Validation.validateKey(metadata(), key);
                DecoratedKey dk = metadata().partitioner.decorateKey(key);

                PartitionUpdate.Builder updateBuilder = collector.getPartitionUpdateBuilder(metadata(), dk, options.getConsistency());

                if (slices == Slices.ALL) // to avoid Slices iterator allocation for a common case
                    addUpdateForKey(updateBuilder, Slice.ALL, params);
                else
                    for (Slice slice : slices)
                        addUpdateForKey(updateBuilder, slice, params);
            }
        }
        else
        {
            NavigableSet<Clustering<?>> clusterings = createClustering(options, state);

            // If some of the restrictions were unspecified (e.g. empty IN restrictions) we do not need to do anything.
            if (restrictions.hasClusteringColumnsRestrictions() && clusterings.isEmpty())
                return;

            RowUpdateBuilder params = makeUpdateBuilder(keys, clusterings, state, options, local, timestamp, nowInSeconds, requestTime);

            for (ByteBuffer key : keys)
            {
                Validation.validateKey(metadata(), key);
                Validation.checkConstraints(metadata(), key);
                DecoratedKey dk = metadata().partitioner.decorateKey(key);

                PartitionUpdate.Builder updateBuilder = collector.getPartitionUpdateBuilder(metadata(), dk, options.getConsistency());

                if (!restrictions.hasClusteringColumnsRestrictions())
                {
                    addUpdateForKey(updateBuilder, Clustering.EMPTY, params);
                }
                else
                {
                    // Clustering keys need to be checked on their own
                    for (Clustering<?> clustering : clusterings)
                    {
                        clustering.validate();
                        checkClusteringConstraints(clustering);
                        addUpdateForKey(updateBuilder, clustering, params);
                    }
                }
            }
        }
    }

    private void checkClusteringConstraints(Clustering<?> clustering)
    {
        for (ColumnMetadata column : metadata.clusteringColumns())
        {
            if (column.hasConstraint())
            {
                try
                {
                    clustering.checkConstraints(column.position(), metadata.comparator, column.getColumnConstraints());
                }
                catch (ConstraintViolationException e)
                {
                    throw new InvalidRequestException(e.getMessage(), e);
                }
            }
        }
    }

    public Slices createSlices(QueryOptions options)
    {
        return restrictions.getSlices(options);
    }

    private RowUpdateBuilder makeUpdateBuilder(Collection<ByteBuffer> keys,
                                               NavigableSet<Clustering<?>> clusterings,
                                               ClientState state,
                                               QueryOptions options,
                                               boolean local,
                                               long timestamp,
                                               long nowInSeconds,
                                               Dispatcher.RequestTime requestTime)
    {
        if (clusterings.contains(Clustering.STATIC_CLUSTERING))
            return makeUpdateParameters(keys,
                                        (clusteringsToFilter) -> new ClusteringIndexSliceFilter(Slices.ALL, false),
                                        clusterings,
                                        state,
                                        options,
                                        DataLimits.cqlLimits(1),
                                        local,
                                        timestamp,
                                        nowInSeconds,
                                        requestTime
            );

        return makeUpdateParameters(keys,
                                    (clusteringsToFilter) -> new ClusteringIndexNamesFilter(clusteringsToFilter, false),
                                    clusterings,
                                    state,
                                    options,
                                    DataLimits.NONE,
                                    local,
                                    timestamp,
                                    nowInSeconds,
                                    requestTime
        );
    }

    private <F> RowUpdateBuilder makeUpdateParameters(Collection<ByteBuffer> keys,
                                                  // filter is needed rarely, so we allocate it on demand
                                                  java.util.function.Function<F, ClusteringIndexFilter> filterBuilder,
                                                  F filterArg,
                                                  ClientState state,
                                                  QueryOptions options,
                                                  DataLimits limits,
                                                  boolean local,
                                                  long timestamp,
                                                  long nowInSeconds,
                                                  Dispatcher.RequestTime requestTime)
    {
        // Some lists operation requires reading
        Map<DecoratedKey, Partition> lists =
            readRequiredLists(keys,
                              filterBuilder,
                              filterArg,
                              limits,
                              local,
                              options.getConsistency(),
                              nowInSeconds,
                              requestTime);

        return new RegularRowUpdateBuilder(metadata(),
                                           state,
                                           options,
                                           getTimestamp(timestamp, options),
                                           nowInSeconds,
                                           getTimeToLive(options),
                                           lists);
    }

    public static abstract class Parsed extends QualifiedStatement
    {
        protected final StatementType type;
        private final Attributes.Raw attrs;
        private final List<ColumnCondition.Raw> conditions;
        private final boolean ifNotExists;
        private final boolean ifExists;
        protected final StatementSource source;

        protected Parsed(QualifiedName name,
                         StatementType type,
                         Attributes.Raw attrs,
                         List<ColumnCondition.Raw> conditions,
                         boolean ifNotExists,
                         boolean ifExists,
                         StatementSource source)
        {
            super(name);
            this.type = type;
            this.attrs = attrs;
            this.conditions = conditions == null ? Collections.emptyList() : conditions;
            this.ifNotExists = ifNotExists;
            this.ifExists = ifExists;
            this.source = source;
        }

        public ModificationStatement prepare(ClientState state)
        {
            return prepare(state, bindVariables);
        }

        public ModificationStatement prepare(ClientState state, VariableSpecifications bindVariables)
        {
            TableMetadata metadata = Schema.instance.validateTable(keyspace(), name());

            Attributes preparedAttributes = attrs.prepare(keyspace(), name());
            preparedAttributes.collectMarkerSpecification(bindVariables);

            Conditions preparedConditions = prepareConditions(metadata, bindVariables);

            // TODO: if this is a txn and has a read name, and updates non-static columns, confirm it selects an entire row
            return prepareInternal(state, metadata, bindVariables, preparedConditions, preparedAttributes);
        }

        /**
         * Returns the column conditions.
         *
         * @param metadata the column family meta data
         * @param bindVariables the bound names
         * @return the column conditions.
         */
        private Conditions prepareConditions(TableMetadata metadata, VariableSpecifications bindVariables)
        {
            // To have both 'IF EXISTS'/'IF NOT EXISTS' and some other conditions doesn't make sense.
            // So far this is enforced by the parser, but let's assert it for sanity if ever the parse changes.
            if (ifExists)
            {
                assert conditions.isEmpty();
                assert !ifNotExists;
                return Conditions.IF_EXISTS_CONDITION;
            }

            if (ifNotExists)
            {
                assert conditions.isEmpty();
                return Conditions.IF_NOT_EXISTS_CONDITION;
            }

            if (conditions.isEmpty())
                return Conditions.EMPTY_CONDITION;

            return prepareColumnConditions(metadata, bindVariables);
        }

        /**
         * Returns the column conditions.
         *
         * @param metadata the column family meta data
         * @param bindVariables the bound names
         * @return the column conditions.
         */
        private ColumnConditions prepareColumnConditions(TableMetadata metadata, VariableSpecifications bindVariables)
        {
            checkNull(attrs.timestamp, "Cannot provide custom timestamp for conditional updates");

            ColumnConditions.Builder builder = ColumnConditions.newBuilder();

            for (ColumnCondition.Raw rawCondition : conditions)
            {
                ColumnCondition condition = rawCondition.prepare(metadata);
                condition.collectMarkerSpecification(bindVariables, attrs);

                builder.add(condition);
            }
            return builder.build();
        }

        protected abstract ModificationStatement prepareInternal(ClientState state,
                                                                 TableMetadata metadata,
                                                                 VariableSpecifications bindVariables,
                                                                 Conditions conditions,
                                                                 Attributes attrs);

        /**
         * Creates the restrictions.
         *
         * @param metadata the table meta data
         * @param boundNames the bound names
         * @param operations the column operations
         * @param where the where clause
         * @param conditions the conditions
         * @return the restrictions
         */
        protected StatementRestrictions newRestrictions(ClientState state,
                                                        TableMetadata metadata,
                                                        VariableSpecifications boundNames,
                                                        Operations operations,
                                                        WhereClause where,
                                                        Conditions conditions,
                                                        Object owner)
        {
            if (where.containsCustomExpressions())
                throw new InvalidRequestException(CUSTOM_EXPRESSIONS_NOT_ALLOWED);

            boolean applyOnlyToStaticColumns = appliesOnlyToStaticColumns(operations, conditions);
            return new StatementRestrictions(state, type, metadata, IndexHints.NONE, where, boundNames, Collections.emptyList(), owner, applyOnlyToStaticColumns, false, false);
        }

        public List<ColumnCondition.Raw> getConditions()
        {
            return conditions;
        }
    }

    private static final Constants.Value ONE = new Constants.Value(ByteBufferUtil.bytes(1));

    public SelectStatement createSelectForTxn()
    {
        // TODO: get working with static-only updates that don't specify any/all primary key columns
        Preconditions.checkState(getRestrictions().hasAllPrimaryKeyColumnsRestrictedByEqualities());
        Selection selection = Selection.forColumns(metadata, Lists.newArrayList(requiresRead), false);
        return new SelectStatement(metadata,
                                   bindVariables,
                                   SelectStatement.defaultParameters,
                                   selection,
                                   getRestrictions(),
                                   false,
                                   null,
                                   null,
                                   ONE,
                                   null,
                                   StatementSource.INTERNAL,
                                   SelectOptions.EMPTY);
    }
}
