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// distinct.cpp
/**
* Copyright (C) 2012-2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery
#include "mongo/platform/basic.h"
#include <string>
#include <vector>
#include "mongo/bson/util/bson_extract.h"
#include "mongo/db/auth/action_set.h"
#include "mongo/db/auth/action_type.h"
#include "mongo/db/auth/privilege.h"
#include "mongo/db/bson/dotted_path_support.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/client.h"
#include "mongo/db/clientcursor.h"
#include "mongo/db/commands.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/db/instance.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/extensions_callback_real.h"
#include "mongo/db/query/cursor_response.h"
#include "mongo/db/query/explain.h"
#include "mongo/db/query/find_common.h"
#include "mongo/db/query/get_executor.h"
#include "mongo/db/query/parsed_distinct.h"
#include "mongo/db/query/plan_summary_stats.h"
#include "mongo/db/query/query_planner_common.h"
#include "mongo/db/query/view_response_formatter.h"
#include "mongo/db/server_options.h"
#include "mongo/db/views/resolved_view.h"
#include "mongo/stdx/memory.h"
#include "mongo/util/log.h"
namespace mongo {
using std::unique_ptr;
using std::string;
using std::stringstream;
namespace dps = ::mongo::dotted_path_support;
class DistinctCommand : public Command {
public:
DistinctCommand() : Command("distinct") {}
virtual bool slaveOk() const {
return false;
}
virtual bool slaveOverrideOk() const {
return true;
}
virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
return false;
}
bool supportsReadConcern() const final {
return true;
}
ReadWriteType getReadWriteType() const {
return ReadWriteType::kRead;
}
std::size_t reserveBytesForReply() const override {
return FindCommon::kInitReplyBufferSize;
}
virtual void addRequiredPrivileges(const std::string& dbname,
const BSONObj& cmdObj,
std::vector<Privilege>* out) {
ActionSet actions;
actions.addAction(ActionType::find);
out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
}
virtual void help(stringstream& help) const {
help << "{ distinct : 'collection name' , key : 'a.b' , query : {} }";
}
virtual Status explain(OperationContext* txn,
const std::string& dbname,
const BSONObj& cmdObj,
ExplainCommon::Verbosity verbosity,
const rpc::ServerSelectionMetadata&,
BSONObjBuilder* out) const {
const string ns = parseNs(dbname, cmdObj);
const NamespaceString nss(ns);
const ExtensionsCallbackReal extensionsCallback(txn, &nss);
auto parsedDistinct = ParsedDistinct::parse(txn, nss, cmdObj, extensionsCallback, true);
if (!parsedDistinct.isOK()) {
return parsedDistinct.getStatus();
}
if (!parsedDistinct.getValue().getQuery()->getQueryRequest().getCollation().isEmpty() &&
serverGlobalParams.featureCompatibility.version.load() ==
ServerGlobalParams::FeatureCompatibility::Version::k32) {
return Status(ErrorCodes::InvalidOptions,
"The featureCompatibilityVersion must be 3.4 to use collation. See "
"http://dochub.mongodb.org/core/3.4-feature-compatibility.");
}
AutoGetCollectionOrViewForRead ctx(txn, ns);
Collection* collection = ctx.getCollection();
if (ctx.getView()) {
ctx.releaseLocksForView();
auto viewAggregation = parsedDistinct.getValue().asAggregationCommand();
if (!viewAggregation.isOK()) {
return viewAggregation.getStatus();
}
std::string errmsg;
(void)Command::findCommand("aggregate")
->run(txn, dbname, viewAggregation.getValue(), 0, errmsg, *out);
return Status::OK();
}
auto executor = getExecutorDistinct(
txn, collection, ns, &parsedDistinct.getValue(), PlanExecutor::YIELD_AUTO);
if (!executor.isOK()) {
return executor.getStatus();
}
Explain::explainStages(executor.getValue().get(), collection, verbosity, out);
return Status::OK();
}
bool run(OperationContext* txn,
const string& dbname,
BSONObj& cmdObj,
int options,
string& errmsg,
BSONObjBuilder& result) {
const string ns = parseNs(dbname, cmdObj);
const NamespaceString nss(ns);
const ExtensionsCallbackReal extensionsCallback(txn, &nss);
auto parsedDistinct = ParsedDistinct::parse(txn, nss, cmdObj, extensionsCallback, false);
if (!parsedDistinct.isOK()) {
return appendCommandStatus(result, parsedDistinct.getStatus());
}
if (!parsedDistinct.getValue().getQuery()->getQueryRequest().getCollation().isEmpty() &&
serverGlobalParams.featureCompatibility.version.load() ==
ServerGlobalParams::FeatureCompatibility::Version::k32) {
return appendCommandStatus(
result,
Status(ErrorCodes::InvalidOptions,
"The featureCompatibilityVersion must be 3.4 to use collation. See "
"http://dochub.mongodb.org/core/3.4-feature-compatibility."));
}
AutoGetCollectionOrViewForRead ctx(txn, ns);
Collection* collection = ctx.getCollection();
if (ctx.getView()) {
ctx.releaseLocksForView();
auto viewAggregation = parsedDistinct.getValue().asAggregationCommand();
if (!viewAggregation.isOK()) {
return appendCommandStatus(result, viewAggregation.getStatus());
}
BSONObjBuilder aggResult;
(void)Command::findCommand("aggregate")
->run(txn, dbname, viewAggregation.getValue(), options, errmsg, aggResult);
if (ResolvedView::isResolvedViewErrorResponse(aggResult.asTempObj())) {
result.appendElements(aggResult.obj());
return false;
}
ViewResponseFormatter formatter(aggResult.obj());
Status formatStatus = formatter.appendAsDistinctResponse(&result);
if (!formatStatus.isOK()) {
return appendCommandStatus(result, formatStatus);
}
return true;
}
auto executor = getExecutorDistinct(
txn, collection, ns, &parsedDistinct.getValue(), PlanExecutor::YIELD_AUTO);
if (!executor.isOK()) {
return appendCommandStatus(result, executor.getStatus());
}
{
stdx::lock_guard<Client>(*txn->getClient());
CurOp::get(txn)->setPlanSummary_inlock(
Explain::getPlanSummary(executor.getValue().get()));
}
string key = cmdObj[ParsedDistinct::kKeyField].valuestrsafe();
int bufSize = BSONObjMaxUserSize - 4096;
BufBuilder bb(bufSize);
char* start = bb.buf();
BSONArrayBuilder arr(bb);
BSONElementSet values(executor.getValue()->getCanonicalQuery()->getCollator());
BSONObj obj;
PlanExecutor::ExecState state;
while (PlanExecutor::ADVANCED == (state = executor.getValue()->getNext(&obj, NULL))) {
// Distinct expands arrays.
//
// If our query is covered, each value of the key should be in the index key and
// available to us without this. If a collection scan is providing the data, we may
// have to expand an array.
BSONElementSet elts;
dps::extractAllElementsAlongPath(obj, key, elts);
for (BSONElementSet::iterator it = elts.begin(); it != elts.end(); ++it) {
BSONElement elt = *it;
if (values.count(elt)) {
continue;
}
int currentBufPos = bb.len();
uassert(17217,
"distinct too big, 16mb cap",
(currentBufPos + elt.size() + 1024) < bufSize);
arr.append(elt);
BSONElement x(start + currentBufPos);
values.insert(x);
}
}
// Return an error if execution fails for any reason.
if (PlanExecutor::FAILURE == state || PlanExecutor::DEAD == state) {
log() << "Plan executor error during distinct command: "
<< redact(PlanExecutor::statestr(state))
<< ", stats: " << redact(Explain::getWinningPlanStats(executor.getValue().get()));
return appendCommandStatus(result,
Status(ErrorCodes::OperationFailed,
str::stream()
<< "Executor error during distinct command: "
<< WorkingSetCommon::toStatusString(obj)));
}
auto curOp = CurOp::get(txn);
// Get summary information about the plan.
PlanSummaryStats stats;
Explain::getSummaryStats(*executor.getValue(), &stats);
if (collection) {
collection->infoCache()->notifyOfQuery(txn, stats.indexesUsed);
}
curOp->debug().setPlanSummaryMetrics(stats);
if (curOp->shouldDBProfile()) {
BSONObjBuilder execStatsBob;
Explain::getWinningPlanStats(executor.getValue().get(), &execStatsBob);
curOp->debug().execStats = execStatsBob.obj();
}
verify(start == bb.buf());
result.appendArray("values", arr.done());
return true;
}
} distinctCmd;
} // namespace mongo