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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.*;
import com.google.common.base.Objects;
import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.auth.Permission;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.ColumnDefinition;
import org.apache.cassandra.cql3.*;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.cql3.restrictions.StatementRestrictions;
import org.apache.cassandra.cql3.selection.RawSelector;
import org.apache.cassandra.cql3.selection.Selection;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.filter.*;
import org.apache.cassandra.db.marshal.CollectionType;
import org.apache.cassandra.db.marshal.CompositeType;
import org.apache.cassandra.db.marshal.Int32Type;
import org.apache.cassandra.db.partitions.PartitionIterator;
import org.apache.cassandra.db.rows.ComplexColumnData;
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.AbstractBounds;
import org.apache.cassandra.exceptions.*;
import org.apache.cassandra.index.SecondaryIndexManager;
import org.apache.cassandra.serializers.MarshalException;
import org.apache.cassandra.service.ClientState;
import org.apache.cassandra.service.ClientWarn;
import org.apache.cassandra.service.QueryState;
import org.apache.cassandra.service.pager.PagingState;
import org.apache.cassandra.service.pager.QueryPager;
import org.apache.cassandra.thrift.ThriftValidation;
import org.apache.cassandra.transport.messages.ResultMessage;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.FBUtilities;
import static org.apache.cassandra.cql3.statements.RequestValidations.checkFalse;
import static org.apache.cassandra.cql3.statements.RequestValidations.checkNotNull;
import static org.apache.cassandra.cql3.statements.RequestValidations.checkTrue;
import static org.apache.cassandra.cql3.statements.RequestValidations.invalidRequest;
import static org.apache.cassandra.utils.ByteBufferUtil.UNSET_BYTE_BUFFER;
/**
* Encapsulates a completely parsed SELECT query, including the target
* column family, expression, result count, and ordering clause.
*
* A number of public methods here are only used internally. However,
* many of these are made accessible for the benefit of custom
* QueryHandler implementations, so before reducing their accessibility
* due consideration should be given.
*/
public class SelectStatement implements CQLStatement
{
private static final Logger logger = LoggerFactory.getLogger(SelectStatement.class);
private static final int DEFAULT_COUNT_PAGE_SIZE = 10000;
private final int boundTerms;
public final CFMetaData cfm;
public final Parameters parameters;
private final Selection selection;
private final Term limit;
private final StatementRestrictions restrictions;
private final boolean isReversed;
/**
* The comparator used to orders results when multiple keys are selected (using IN).
*/
private final Comparator> orderingComparator;
private final ColumnFilter queriedColumns;
// Used by forSelection below
private static final Parameters defaultParameters = new Parameters(Collections.emptyMap(), false, false, false);
public SelectStatement(CFMetaData cfm,
int boundTerms,
Parameters parameters,
Selection selection,
StatementRestrictions restrictions,
boolean isReversed,
Comparator> orderingComparator,
Term limit)
{
this.cfm = cfm;
this.boundTerms = boundTerms;
this.selection = selection;
this.restrictions = restrictions;
this.isReversed = isReversed;
this.orderingComparator = orderingComparator;
this.parameters = parameters;
this.limit = limit;
this.queriedColumns = gatherQueriedColumns();
}
public Iterable getFunctions()
{
return Iterables.concat(selection.getFunctions(),
restrictions.getFunctions(),
limit != null ? limit.getFunctions() : Collections.emptySet());
}
// Note that the queried columns internally is different from the one selected by the
// user as it also include any column for which we have a restriction on.
private ColumnFilter gatherQueriedColumns()
{
if (selection.isWildcard())
return ColumnFilter.all(cfm);
ColumnFilter.Builder builder = ColumnFilter.allColumnsBuilder(cfm);
// Adds all selected columns
for (ColumnDefinition def : selection.getColumns())
if (!def.isPrimaryKeyColumn())
builder.add(def);
// as well as any restricted column (so we can actually apply the restriction)
builder.addAll(restrictions.nonPKRestrictedColumns(true));
return builder.build();
}
// Creates a simple select based on the given selection.
// Note that the results select statement should not be used for actual queries, but only for processing already
// queried data through processColumnFamily.
static SelectStatement forSelection(CFMetaData cfm, Selection selection)
{
return new SelectStatement(cfm,
0,
defaultParameters,
selection,
StatementRestrictions.empty(StatementType.SELECT, cfm),
false,
null,
null);
}
public ResultSet.ResultMetadata getResultMetadata()
{
return selection.getResultMetadata(parameters.isJson);
}
public int getBoundTerms()
{
return boundTerms;
}
public void checkAccess(ClientState state) throws InvalidRequestException, UnauthorizedException
{
if (cfm.isView())
{
CFMetaData baseTable = View.findBaseTable(keyspace(), columnFamily());
if (baseTable != null)
state.hasColumnFamilyAccess(baseTable, Permission.SELECT);
}
else
{
state.hasColumnFamilyAccess(cfm, Permission.SELECT);
}
for (Function function : getFunctions())
state.ensureHasPermission(Permission.EXECUTE, function);
}
public void validate(ClientState state) throws InvalidRequestException
{
// Nothing to do, all validation has been done by RawStatement.prepare()
}
public ResultMessage.Rows execute(QueryState state, QueryOptions options) throws RequestExecutionException, RequestValidationException
{
ConsistencyLevel cl = options.getConsistency();
checkNotNull(cl, "Invalid empty consistency level");
cl.validateForRead(keyspace());
int nowInSec = FBUtilities.nowInSeconds();
int userLimit = getLimit(options);
ReadQuery query = getQuery(options, nowInSec, userLimit);
int pageSize = getPageSize(options);
if (pageSize <= 0 || query.limits().count() <= pageSize)
return execute(query, options, state, nowInSec, userLimit);
QueryPager pager = query.getPager(options.getPagingState(), options.getProtocolVersion());
return execute(Pager.forDistributedQuery(pager, cl, state.getClientState()), options, pageSize, nowInSec, userLimit);
}
private int getPageSize(QueryOptions options)
{
int pageSize = options.getPageSize();
// An aggregation query will never be paged for the user, but we always page it internally to avoid OOM.
// If we user provided a pageSize we'll use that to page internally (because why not), otherwise we use our default
// Note that if there are some nodes in the cluster with a version less than 2.0, we can't use paging (CASSANDRA-6707).
if (selection.isAggregate() && pageSize <= 0)
pageSize = DEFAULT_COUNT_PAGE_SIZE;
return pageSize;
}
public ReadQuery getQuery(QueryOptions options, int nowInSec) throws RequestValidationException
{
return getQuery(options, nowInSec, getLimit(options));
}
public ReadQuery getQuery(QueryOptions options, int nowInSec, int userLimit) throws RequestValidationException
{
DataLimits limit = getDataLimits(userLimit);
if (restrictions.isKeyRange() || restrictions.usesSecondaryIndexing())
return getRangeCommand(options, limit, nowInSec);
return getSliceCommands(options, limit, nowInSec);
}
private ResultMessage.Rows execute(ReadQuery query,
QueryOptions options,
QueryState state,
int nowInSec,
int userLimit) throws RequestValidationException, RequestExecutionException
{
try (PartitionIterator data = query.execute(options.getConsistency(), state.getClientState()))
{
return processResults(data, options, nowInSec, userLimit);
}
}
// Simple wrapper class to avoid some code duplication
private static abstract class Pager
{
protected QueryPager pager;
protected Pager(QueryPager pager)
{
this.pager = pager;
}
public static Pager forInternalQuery(QueryPager pager, ReadExecutionController executionController)
{
return new InternalPager(pager, executionController);
}
public static Pager forDistributedQuery(QueryPager pager, ConsistencyLevel consistency, ClientState clientState)
{
return new NormalPager(pager, consistency, clientState);
}
public boolean isExhausted()
{
return pager.isExhausted();
}
public PagingState state()
{
return pager.state();
}
public abstract PartitionIterator fetchPage(int pageSize);
public static class NormalPager extends Pager
{
private final ConsistencyLevel consistency;
private final ClientState clientState;
private NormalPager(QueryPager pager, ConsistencyLevel consistency, ClientState clientState)
{
super(pager);
this.consistency = consistency;
this.clientState = clientState;
}
public PartitionIterator fetchPage(int pageSize)
{
return pager.fetchPage(pageSize, consistency, clientState);
}
}
public static class InternalPager extends Pager
{
private final ReadExecutionController executionController;
private InternalPager(QueryPager pager, ReadExecutionController executionController)
{
super(pager);
this.executionController = executionController;
}
public PartitionIterator fetchPage(int pageSize)
{
return pager.fetchPageInternal(pageSize, executionController);
}
}
}
private ResultMessage.Rows execute(Pager pager,
QueryOptions options,
int pageSize,
int nowInSec,
int userLimit) throws RequestValidationException, RequestExecutionException
{
if (selection.isAggregate())
return pageAggregateQuery(pager, options, pageSize, nowInSec);
// We can't properly do post-query ordering if we page (see #6722)
checkFalse(needsPostQueryOrdering(),
"Cannot page queries with both ORDER BY and a IN restriction on the partition key;"
+ " you must either remove the ORDER BY or the IN and sort client side, or disable paging for this query");
ResultMessage.Rows msg;
try (PartitionIterator page = pager.fetchPage(pageSize))
{
msg = processResults(page, options, nowInSec, userLimit);
}
// Please note that the isExhausted state of the pager only gets updated when we've closed the page, so this
// shouldn't be moved inside the 'try' above.
if (!pager.isExhausted())
msg.result.metadata.setHasMorePages(pager.state());
return msg;
}
private ResultMessage.Rows pageAggregateQuery(Pager pager, QueryOptions options, int pageSize, int nowInSec)
throws RequestValidationException, RequestExecutionException
{
if (!restrictions.hasPartitionKeyRestrictions())
{
logger.warn("Aggregation query used without partition key");
ClientWarn.instance.warn("Aggregation query used without partition key");
}
else if (restrictions.keyIsInRelation())
{
logger.warn("Aggregation query used on multiple partition keys (IN restriction)");
ClientWarn.instance.warn("Aggregation query used on multiple partition keys (IN restriction)");
}
Selection.ResultSetBuilder result = selection.resultSetBuilder(parameters.isJson);
while (!pager.isExhausted())
{
try (PartitionIterator iter = pager.fetchPage(pageSize))
{
while (iter.hasNext())
{
try (RowIterator partition = iter.next())
{
processPartition(partition, options, result, nowInSec);
}
}
}
}
return new ResultMessage.Rows(result.build(options.getProtocolVersion()));
}
private ResultMessage.Rows processResults(PartitionIterator partitions,
QueryOptions options,
int nowInSec,
int userLimit) throws RequestValidationException
{
ResultSet rset = process(partitions, options, nowInSec, userLimit);
return new ResultMessage.Rows(rset);
}
public ResultMessage.Rows executeInternal(QueryState state, QueryOptions options) throws RequestExecutionException, RequestValidationException
{
int nowInSec = FBUtilities.nowInSeconds();
int userLimit = getLimit(options);
ReadQuery query = getQuery(options, nowInSec, userLimit);
int pageSize = getPageSize(options);
try (ReadExecutionController executionController = query.executionController())
{
if (pageSize <= 0 || query.limits().count() <= pageSize)
{
try (PartitionIterator data = query.executeInternal(executionController))
{
return processResults(data, options, nowInSec, userLimit);
}
}
else
{
QueryPager pager = query.getPager(options.getPagingState(), options.getProtocolVersion());
return execute(Pager.forInternalQuery(pager, executionController), options, pageSize, nowInSec, userLimit);
}
}
}
public ResultSet process(PartitionIterator partitions, int nowInSec) throws InvalidRequestException
{
return process(partitions, QueryOptions.DEFAULT, nowInSec, getLimit(QueryOptions.DEFAULT));
}
public String keyspace()
{
return cfm.ksName;
}
public String columnFamily()
{
return cfm.cfName;
}
/**
* May be used by custom QueryHandler implementations
*/
public Selection getSelection()
{
return selection;
}
/**
* May be used by custom QueryHandler implementations
*/
public StatementRestrictions getRestrictions()
{
return restrictions;
}
private ReadQuery getSliceCommands(QueryOptions options, DataLimits limit, int nowInSec) throws RequestValidationException
{
Collection keys = restrictions.getPartitionKeys(options);
if (keys.isEmpty())
return ReadQuery.EMPTY;
ClusteringIndexFilter filter = makeClusteringIndexFilter(options);
if (filter == null)
return ReadQuery.EMPTY;
RowFilter rowFilter = getRowFilter(options);
// Note that we use the total limit for every key, which is potentially inefficient.
// However, IN + LIMIT is not a very sensible choice.
List commands = new ArrayList<>(keys.size());
for (ByteBuffer key : keys)
{
QueryProcessor.validateKey(key);
DecoratedKey dk = cfm.decorateKey(ByteBufferUtil.clone(key));
commands.add(SinglePartitionReadCommand.create(cfm, nowInSec, queriedColumns, rowFilter, limit, dk, filter));
}
return new SinglePartitionReadCommand.Group(commands, limit);
}
/**
* Returns a read command that can be used internally to filter individual rows for materialized views.
*/
public SinglePartitionReadCommand internalReadForView(DecoratedKey key, int nowInSec)
{
QueryOptions options = QueryOptions.forInternalCalls(Collections.emptyList());
ClusteringIndexFilter filter = makeClusteringIndexFilter(options);
RowFilter rowFilter = getRowFilter(options);
return SinglePartitionReadCommand.create(cfm, nowInSec, queriedColumns, rowFilter, DataLimits.NONE, key, filter);
}
private ReadQuery getRangeCommand(QueryOptions options, DataLimits limit, int nowInSec) throws RequestValidationException
{
ClusteringIndexFilter clusteringIndexFilter = makeClusteringIndexFilter(options);
if (clusteringIndexFilter == null)
return ReadQuery.EMPTY;
RowFilter rowFilter = getRowFilter(options);
// The LIMIT provided by the user is the number of CQL row he wants returned.
// We want to have getRangeSlice to count the number of columns, not the number of keys.
AbstractBounds keyBounds = restrictions.getPartitionKeyBounds(options);
if (keyBounds == null)
return ReadQuery.EMPTY;
PartitionRangeReadCommand command = new PartitionRangeReadCommand(cfm,
nowInSec,
queriedColumns,
rowFilter,
limit,
new DataRange(keyBounds, clusteringIndexFilter),
Optional.empty());
// If there's a secondary index that the command can use, have it validate
// the request parameters. Note that as a side effect, if a viable Index is
// identified by the CFS's index manager, it will be cached in the command
// and serialized during distribution to replicas in order to avoid performing
// further lookups.
command.maybeValidateIndex();
return command;
}
private ClusteringIndexFilter makeClusteringIndexFilter(QueryOptions options)
throws InvalidRequestException
{
if (parameters.isDistinct)
{
// We need to be able to distinguish between partition having live rows and those that don't. But
// doing so is not trivial since "having a live row" depends potentially on
// 1) when the query is performed, due to TTLs
// 2) how thing reconcile together between different nodes
// so that it's hard to really optimize properly internally. So to keep it simple, we simply query
// for the first row of the partition and hence uses Slices.ALL. We'll limit it to the first live
// row however in getLimit().
return new ClusteringIndexSliceFilter(Slices.ALL, false);
}
if (restrictions.isColumnRange())
{
Slices slices = makeSlices(options);
if (slices == Slices.NONE && !selection.containsStaticColumns())
return null;
return new ClusteringIndexSliceFilter(slices, isReversed);
}
else
{
NavigableSet clusterings = getRequestedRows(options);
// We can have no clusterings if either we're only selecting the static columns, or if we have
// a 'IN ()' for clusterings. In that case, we still want to query if some static columns are
// queried. But we're fine otherwise.
if (clusterings.isEmpty() && queriedColumns.fetchedColumns().statics.isEmpty())
return null;
return new ClusteringIndexNamesFilter(clusterings, isReversed);
}
}
private Slices makeSlices(QueryOptions options)
throws InvalidRequestException
{
SortedSet startBounds = restrictions.getClusteringColumnsBounds(Bound.START, options);
SortedSet endBounds = restrictions.getClusteringColumnsBounds(Bound.END, options);
assert startBounds.size() == endBounds.size();
// The case where startBounds == 1 is common enough that it's worth optimizing
if (startBounds.size() == 1)
{
Slice.Bound start = startBounds.first();
Slice.Bound end = endBounds.first();
return cfm.comparator.compare(start, end) > 0
? Slices.NONE
: Slices.with(cfm.comparator, Slice.make(start, end));
}
Slices.Builder builder = new Slices.Builder(cfm.comparator, startBounds.size());
Iterator startIter = startBounds.iterator();
Iterator endIter = endBounds.iterator();
while (startIter.hasNext() && endIter.hasNext())
{
Slice.Bound start = startIter.next();
Slice.Bound end = endIter.next();
// Ignore slices that are nonsensical
if (cfm.comparator.compare(start, end) > 0)
continue;
builder.add(start, end);
}
return builder.build();
}
private DataLimits getDataLimits(int userLimit)
{
int cqlRowLimit = DataLimits.NO_LIMIT;
// If we aggregate, the limit really apply to the number of rows returned to the user, not to what is queried, and
// since in practice we currently only aggregate at top level (we have no GROUP BY support yet), we'll only ever
// return 1 result and can therefore basically ignore the user LIMIT in this case.
// Whenever we support GROUP BY, we'll have to add a new DataLimits kind that knows how things are grouped and is thus
// able to apply the user limit properly.
// If we do post ordering we need to get all the results sorted before we can trim them.
if (!selection.isAggregate() && !needsPostQueryOrdering())
cqlRowLimit = userLimit;
if (parameters.isDistinct)
return cqlRowLimit == DataLimits.NO_LIMIT ? DataLimits.DISTINCT_NONE : DataLimits.distinctLimits(cqlRowLimit);
return cqlRowLimit == DataLimits.NO_LIMIT ? DataLimits.NONE : DataLimits.cqlLimits(cqlRowLimit);
}
/**
* Returns the limit specified by the user.
* May be used by custom QueryHandler implementations
*
* @return the limit specified by the user or DataLimits.NO_LIMIT if no value
* as been specified.
*/
public int getLimit(QueryOptions options)
{
int userLimit = DataLimits.NO_LIMIT;
if (limit != null)
{
ByteBuffer b = checkNotNull(limit.bindAndGet(options), "Invalid null value of limit");
// treat UNSET limit value as 'unlimited'
if (b != UNSET_BYTE_BUFFER)
{
try
{
Int32Type.instance.validate(b);
userLimit = Int32Type.instance.compose(b);
checkTrue(userLimit > 0, "LIMIT must be strictly positive");
}
catch (MarshalException e)
{
throw new InvalidRequestException("Invalid limit value");
}
}
}
return userLimit;
}
private NavigableSet getRequestedRows(QueryOptions options) throws InvalidRequestException
{
// Note: getRequestedColumns don't handle static columns, but due to CASSANDRA-5762
// we always do a slice for CQL3 tables, so it's ok to ignore them here
assert !restrictions.isColumnRange();
return restrictions.getClusteringColumns(options);
}
/**
* May be used by custom QueryHandler implementations
*/
public RowFilter getRowFilter(QueryOptions options) throws InvalidRequestException
{
ColumnFamilyStore cfs = Keyspace.open(keyspace()).getColumnFamilyStore(columnFamily());
SecondaryIndexManager secondaryIndexManager = cfs.indexManager;
RowFilter filter = restrictions.getRowFilter(secondaryIndexManager, options);
return filter;
}
private ResultSet process(PartitionIterator partitions,
QueryOptions options,
int nowInSec,
int userLimit) throws InvalidRequestException
{
Selection.ResultSetBuilder result = selection.resultSetBuilder(parameters.isJson);
while (partitions.hasNext())
{
try (RowIterator partition = partitions.next())
{
processPartition(partition, options, result, nowInSec);
}
}
ResultSet cqlRows = result.build(options.getProtocolVersion());
orderResults(cqlRows);
cqlRows.trim(userLimit);
return cqlRows;
}
public static ByteBuffer[] getComponents(CFMetaData cfm, DecoratedKey dk)
{
ByteBuffer key = dk.getKey();
if (cfm.getKeyValidator() instanceof CompositeType)
{
return ((CompositeType)cfm.getKeyValidator()).split(key);
}
else
{
return new ByteBuffer[]{ key };
}
}
// Used by ModificationStatement for CAS operations
void processPartition(RowIterator partition, QueryOptions options, Selection.ResultSetBuilder result, int nowInSec)
throws InvalidRequestException
{
int protocolVersion = options.getProtocolVersion();
ByteBuffer[] keyComponents = getComponents(cfm, partition.partitionKey());
Row staticRow = partition.staticRow();
// If there is no rows, and there's no restriction on clustering/regular columns,
// then provided the select was a full partition selection (either by partition key and/or by static column),
// we want to include static columns and we're done.
if (!partition.hasNext())
{
if (!staticRow.isEmpty() && (!restrictions.hasClusteringColumnsRestriction() || cfm.isStaticCompactTable()))
{
result.newRow(protocolVersion);
for (ColumnDefinition def : selection.getColumns())
{
switch (def.kind)
{
case PARTITION_KEY:
result.add(keyComponents[def.position()]);
break;
case STATIC:
addValue(result, def, staticRow, nowInSec, protocolVersion);
break;
default:
result.add((ByteBuffer)null);
}
}
}
return;
}
while (partition.hasNext())
{
Row row = partition.next();
result.newRow(protocolVersion);
// Respect selection order
for (ColumnDefinition def : selection.getColumns())
{
switch (def.kind)
{
case PARTITION_KEY:
result.add(keyComponents[def.position()]);
break;
case CLUSTERING:
result.add(row.clustering().get(def.position()));
break;
case REGULAR:
addValue(result, def, row, nowInSec, protocolVersion);
break;
case STATIC:
addValue(result, def, staticRow, nowInSec, protocolVersion);
break;
}
}
}
}
private static void addValue(Selection.ResultSetBuilder result, ColumnDefinition def, Row row, int nowInSec, int protocolVersion)
{
if (def.isComplex())
{
// Collections are the only complex types we have so far
assert def.type.isCollection() && def.type.isMultiCell();
ComplexColumnData complexData = row.getComplexColumnData(def);
if (complexData == null)
result.add((ByteBuffer)null);
else
result.add(((CollectionType)def.type).serializeForNativeProtocol(def, complexData.iterator(), protocolVersion));
}
else
{
result.add(row.getCell(def), nowInSec);
}
}
private boolean needsPostQueryOrdering()
{
// We need post-query ordering only for queries with IN on the partition key and an ORDER BY.
return restrictions.keyIsInRelation() && !parameters.orderings.isEmpty();
}
/**
* Orders results when multiple keys are selected (using IN)
*/
private void orderResults(ResultSet cqlRows)
{
if (cqlRows.size() == 0 || !needsPostQueryOrdering())
return;
Collections.sort(cqlRows.rows, orderingComparator);
}
public static class RawStatement extends CFStatement
{
public final Parameters parameters;
public final List selectClause;
public final WhereClause whereClause;
public final Term.Raw limit;
public RawStatement(CFName cfName, Parameters parameters, List selectClause, WhereClause whereClause, Term.Raw limit)
{
super(cfName);
this.parameters = parameters;
this.selectClause = selectClause;
this.whereClause = whereClause;
this.limit = limit;
}
public ParsedStatement.Prepared prepare() throws InvalidRequestException
{
return prepare(false);
}
public ParsedStatement.Prepared prepare(boolean forView) throws InvalidRequestException
{
CFMetaData cfm = ThriftValidation.validateColumnFamily(keyspace(), columnFamily());
VariableSpecifications boundNames = getBoundVariables();
Selection selection = selectClause.isEmpty()
? Selection.wildcard(cfm)
: Selection.fromSelectors(cfm, selectClause);
StatementRestrictions restrictions = prepareRestrictions(cfm, boundNames, selection, forView);
if (parameters.isDistinct)
validateDistinctSelection(cfm, selection, restrictions);
Comparator> orderingComparator = null;
boolean isReversed = false;
if (!parameters.orderings.isEmpty())
{
assert !forView;
verifyOrderingIsAllowed(restrictions);
orderingComparator = getOrderingComparator(cfm, selection, restrictions);
isReversed = isReversed(cfm);
if (isReversed)
orderingComparator = Collections.reverseOrder(orderingComparator);
}
checkNeedsFiltering(restrictions);
SelectStatement stmt = new SelectStatement(cfm,
boundNames.size(),
parameters,
selection,
restrictions,
isReversed,
orderingComparator,
prepareLimit(boundNames));
return new ParsedStatement.Prepared(stmt, boundNames, boundNames.getPartitionKeyBindIndexes(cfm));
}
/**
* Prepares the restrictions.
*
* @param cfm the column family meta data
* @param boundNames the variable specifications
* @param selection the selection
* @return the restrictions
* @throws InvalidRequestException if a problem occurs while building the restrictions
*/
private StatementRestrictions prepareRestrictions(CFMetaData cfm,
VariableSpecifications boundNames,
Selection selection,
boolean forView) throws InvalidRequestException
{
try
{
return new StatementRestrictions(StatementType.SELECT,
cfm,
whereClause,
boundNames,
selection.containsOnlyStaticColumns(),
selection.containsACollection(),
parameters.allowFiltering,
forView);
}
catch (UnrecognizedEntityException e)
{
if (containsAlias(e.entity))
throw invalidRequest("Aliases aren't allowed in the where clause ('%s')", e.relation);
throw e;
}
}
/** Returns a Term for the limit or null if no limit is set */
private Term prepareLimit(VariableSpecifications boundNames) throws InvalidRequestException
{
if (limit == null)
return null;
Term prepLimit = limit.prepare(keyspace(), limitReceiver());
prepLimit.collectMarkerSpecification(boundNames);
return prepLimit;
}
private static void verifyOrderingIsAllowed(StatementRestrictions restrictions) throws InvalidRequestException
{
checkFalse(restrictions.usesSecondaryIndexing(), "ORDER BY with 2ndary indexes is not supported.");
checkFalse(restrictions.isKeyRange(), "ORDER BY is only supported when the partition key is restricted by an EQ or an IN.");
}
private static void validateDistinctSelection(CFMetaData cfm,
Selection selection,
StatementRestrictions restrictions)
throws InvalidRequestException
{
Collection requestedColumns = selection.getColumns();
for (ColumnDefinition def : requestedColumns)
checkFalse(!def.isPartitionKey() && !def.isStatic(),
"SELECT DISTINCT queries must only request partition key columns and/or static columns (not %s)",
def.name);
// If it's a key range, we require that all partition key columns are selected so we don't have to bother
// with post-query grouping.
if (!restrictions.isKeyRange())
return;
for (ColumnDefinition def : cfm.partitionKeyColumns())
checkTrue(requestedColumns.contains(def),
"SELECT DISTINCT queries must request all the partition key columns (missing %s)", def.name);
}
private void handleUnrecognizedOrderingColumn(ColumnIdentifier column) throws InvalidRequestException
{
checkFalse(containsAlias(column), "Aliases are not allowed in order by clause ('%s')", column);
checkFalse(true, "Order by on unknown column %s", column);
}
private Comparator> getOrderingComparator(CFMetaData cfm,
Selection selection,
StatementRestrictions restrictions)
throws InvalidRequestException
{
if (!restrictions.keyIsInRelation())
return null;
Map orderingIndexes = getOrderingIndex(cfm, selection);
List idToSort = new ArrayList();
List> sorters = new ArrayList>();
for (ColumnIdentifier.Raw raw : parameters.orderings.keySet())
{
ColumnIdentifier identifier = raw.prepare(cfm);
ColumnDefinition orderingColumn = cfm.getColumnDefinition(identifier);
idToSort.add(orderingIndexes.get(orderingColumn.name));
sorters.add(orderingColumn.type);
}
return idToSort.size() == 1 ? new SingleColumnComparator(idToSort.get(0), sorters.get(0))
: new CompositeComparator(sorters, idToSort);
}
private Map getOrderingIndex(CFMetaData cfm, Selection selection)
throws InvalidRequestException
{
// If we order post-query (see orderResults), the sorted column needs to be in the ResultSet for sorting,
// even if we don't
// ultimately ship them to the client (CASSANDRA-4911).
Map orderingIndexes = new HashMap<>();
for (ColumnIdentifier.Raw raw : parameters.orderings.keySet())
{
ColumnIdentifier column = raw.prepare(cfm);
final ColumnDefinition def = cfm.getColumnDefinition(column);
if (def == null)
handleUnrecognizedOrderingColumn(column);
int index = selection.getResultSetIndex(def);
if (index < 0)
index = selection.addColumnForOrdering(def);
orderingIndexes.put(def.name, index);
}
return orderingIndexes;
}
private boolean isReversed(CFMetaData cfm) throws InvalidRequestException
{
Boolean[] reversedMap = new Boolean[cfm.clusteringColumns().size()];
int i = 0;
for (Map.Entry entry : parameters.orderings.entrySet())
{
ColumnIdentifier column = entry.getKey().prepare(cfm);
boolean reversed = entry.getValue();
ColumnDefinition def = cfm.getColumnDefinition(column);
if (def == null)
handleUnrecognizedOrderingColumn(column);
checkTrue(def.isClusteringColumn(),
"Order by is currently only supported on the clustered columns of the PRIMARY KEY, got %s", column);
checkTrue(i++ == def.position(),
"Order by currently only support the ordering of columns following their declared order in the PRIMARY KEY");
reversedMap[def.position()] = (reversed != def.isReversedType());
}
// Check that all boolean in reversedMap, if set, agrees
Boolean isReversed = null;
for (Boolean b : reversedMap)
{
// Column on which order is specified can be in any order
if (b == null)
continue;
if (isReversed == null)
{
isReversed = b;
continue;
}
checkTrue(isReversed.equals(b), "Unsupported order by relation");
}
assert isReversed != null;
return isReversed;
}
/** If ALLOW FILTERING was not specified, this verifies that it is not needed */
private void checkNeedsFiltering(StatementRestrictions restrictions) throws InvalidRequestException
{
// non-key-range non-indexed queries cannot involve filtering underneath
if (!parameters.allowFiltering && (restrictions.isKeyRange() || restrictions.usesSecondaryIndexing()))
{
// We will potentially filter data if either:
// - Have more than one IndexExpression
// - Have no index expression and the row filter is not the identity
checkFalse(restrictions.needFiltering(), StatementRestrictions.REQUIRES_ALLOW_FILTERING_MESSAGE);
}
}
private boolean containsAlias(final ColumnIdentifier name)
{
return Iterables.any(selectClause, new Predicate()
{
public boolean apply(RawSelector raw)
{
return name.equals(raw.alias);
}
});
}
private ColumnSpecification limitReceiver()
{
return new ColumnSpecification(keyspace(), columnFamily(), new ColumnIdentifier("[limit]", true), Int32Type.instance);
}
@Override
public String toString()
{
return Objects.toStringHelper(this)
.add("name", cfName)
.add("selectClause", selectClause)
.add("whereClause", whereClause)
.add("isDistinct", parameters.isDistinct)
.toString();
}
}
public static class Parameters
{
// Public because CASSANDRA-9858
public final Map orderings;
public final boolean isDistinct;
public final boolean allowFiltering;
public final boolean isJson;
public Parameters(Map orderings,
boolean isDistinct,
boolean allowFiltering,
boolean isJson)
{
this.orderings = orderings;
this.isDistinct = isDistinct;
this.allowFiltering = allowFiltering;
this.isJson = isJson;
}
}
private static abstract class ColumnComparator implements Comparator
{
protected final int compare(Comparator comparator, ByteBuffer aValue, ByteBuffer bValue)
{
if (aValue == null)
return bValue == null ? 0 : -1;
return bValue == null ? 1 : comparator.compare(aValue, bValue);
}
}
/**
* Used in orderResults(...) method when single 'ORDER BY' condition where given
*/
private static class SingleColumnComparator extends ColumnComparator>
{
private final int index;
private final Comparator comparator;
public SingleColumnComparator(int columnIndex, Comparator orderer)
{
index = columnIndex;
comparator = orderer;
}
public int compare(List a, List b)
{
return compare(comparator, a.get(index), b.get(index));
}
}
/**
* Used in orderResults(...) method when multiple 'ORDER BY' conditions where given
*/
private static class CompositeComparator extends ColumnComparator>
{
private final List> orderTypes;
private final List positions;
private CompositeComparator(List> orderTypes, List positions)
{
this.orderTypes = orderTypes;
this.positions = positions;
}
public int compare(List a, List b)
{
for (int i = 0; i < positions.size(); i++)
{
Comparator type = orderTypes.get(i);
int columnPos = positions.get(i);
int comparison = compare(type, a.get(columnPos), b.get(columnPos));
if (comparison != 0)
return comparison;
}
return 0;
}
}
}
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