250 lines
8.7 KiB
C++
250 lines
8.7 KiB
C++
// query.h
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/**
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* Copyright (C) 2008 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "../../pch.h"
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#include "../../util/net/message.h"
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#include "../dbmessage.h"
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#include "../jsobj.h"
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#include "../diskloc.h"
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#include "../projection.h"
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// struct QueryOptions, QueryResult, QueryResultFlags in:
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#include "../../client/dbclient.h"
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namespace mongo {
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extern const int MaxBytesToReturnToClientAtOnce;
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QueryResult* processGetMore(const char *ns, int ntoreturn, long long cursorid , CurOp& op, int pass, bool& exhaust);
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long long runCount(const char *ns, const BSONObj& cmd, string& err);
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const char * runQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result);
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/* This is for languages whose "objects" are not well ordered (JSON is well ordered).
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[ { a : ... } , { b : ... } ] -> { a : ..., b : ... }
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*/
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inline BSONObj transformOrderFromArrayFormat(BSONObj order) {
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/* note: this is slow, but that is ok as order will have very few pieces */
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BSONObjBuilder b;
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char p[2] = "0";
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while ( 1 ) {
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BSONObj j = order.getObjectField(p);
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if ( j.isEmpty() )
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break;
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BSONElement e = j.firstElement();
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uassert( 10102 , "bad order array", !e.eoo());
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uassert( 10103 , "bad order array [2]", e.isNumber());
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b.append(e);
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(*p)++;
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uassert( 10104 , "too many ordering elements", *p <= '9');
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}
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return b.obj();
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}
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/**
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* this represents a total user query
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* includes fields from the query message, both possible query levels
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* parses everything up front
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*/
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class ParsedQuery : boost::noncopyable {
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public:
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ParsedQuery( QueryMessage& qm )
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: _ns( qm.ns ) , _ntoskip( qm.ntoskip ) , _ntoreturn( qm.ntoreturn ) , _options( qm.queryOptions ) {
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init( qm.query );
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initFields( qm.fields );
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}
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ParsedQuery( const char* ns , int ntoskip , int ntoreturn , int queryoptions , const BSONObj& query , const BSONObj& fields )
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: _ns( ns ) , _ntoskip( ntoskip ) , _ntoreturn( ntoreturn ) , _options( queryoptions ) {
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init( query );
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initFields( fields );
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}
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const char * ns() const { return _ns; }
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bool isLocalDB() const { return strncmp(_ns, "local.", 6) == 0; }
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const BSONObj& getFilter() const { return _filter; }
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Projection* getFields() const { return _fields.get(); }
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shared_ptr<Projection> getFieldPtr() const { return _fields; }
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int getSkip() const { return _ntoskip; }
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int getNumToReturn() const { return _ntoreturn; }
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bool wantMore() const { return _wantMore; }
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int getOptions() const { return _options; }
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bool hasOption( int x ) const { return x & _options; }
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bool isExplain() const { return _explain; }
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bool isSnapshot() const { return _snapshot; }
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bool returnKey() const { return _returnKey; }
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bool showDiskLoc() const { return _showDiskLoc; }
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const BSONObj& getMin() const { return _min; }
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const BSONObj& getMax() const { return _max; }
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const BSONObj& getOrder() const { return _order; }
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const BSONElement& getHint() const { return _hint; }
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int getMaxScan() const { return _maxScan; }
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bool couldBeCommand() const {
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/* we assume you are using findOne() for running a cmd... */
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return _ntoreturn == 1 && strstr( _ns , ".$cmd" );
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}
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bool hasIndexSpecifier() const {
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return ! _hint.eoo() || ! _min.isEmpty() || ! _max.isEmpty();
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}
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/* if ntoreturn is zero, we return up to 101 objects. on the subsequent getmore, there
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is only a size limit. The idea is that on a find() where one doesn't use much results,
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we don't return much, but once getmore kicks in, we start pushing significant quantities.
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The n limit (vs. size) is important when someone fetches only one small field from big
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objects, which causes massive scanning server-side.
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*/
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bool enoughForFirstBatch( int n , int len ) const {
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if ( _ntoreturn == 0 )
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return ( len > 1024 * 1024 ) || n >= 101;
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return n >= _ntoreturn || len > MaxBytesToReturnToClientAtOnce;
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}
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bool enough( int n ) const {
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if ( _ntoreturn == 0 )
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return false;
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return n >= _ntoreturn;
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}
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private:
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void init( const BSONObj& q ) {
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_reset();
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uassert( 10105 , "bad skip value in query", _ntoskip >= 0);
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if ( _ntoreturn < 0 ) {
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/* _ntoreturn greater than zero is simply a hint on how many objects to send back per
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"cursor batch".
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A negative number indicates a hard limit.
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*/
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_wantMore = false;
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_ntoreturn = -_ntoreturn;
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}
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BSONElement e = q["query"];
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if ( ! e.isABSONObj() )
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e = q["$query"];
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if ( e.isABSONObj() ) {
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_filter = e.embeddedObject();
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_initTop( q );
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}
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else {
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_filter = q;
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}
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}
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void _reset() {
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_wantMore = true;
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_explain = false;
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_snapshot = false;
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_returnKey = false;
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_showDiskLoc = false;
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_maxScan = 0;
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}
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void _initTop( const BSONObj& top ) {
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BSONObjIterator i( top );
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while ( i.more() ) {
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BSONElement e = i.next();
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const char * name = e.fieldName();
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if ( strcmp( "$orderby" , name ) == 0 ||
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strcmp( "orderby" , name ) == 0 ) {
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if ( e.type() == Object ) {
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_order = e.embeddedObject();
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}
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else if ( e.type() == Array ) {
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_order = transformOrderFromArrayFormat( _order );
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}
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else {
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uasserted(13513, "sort must be an object or array");
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}
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continue;
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}
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if( *name == '$' ) {
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name++;
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if ( strcmp( "explain" , name ) == 0 )
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_explain = e.trueValue();
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else if ( strcmp( "snapshot" , name ) == 0 )
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_snapshot = e.trueValue();
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else if ( strcmp( "min" , name ) == 0 )
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_min = e.embeddedObject();
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else if ( strcmp( "max" , name ) == 0 )
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_max = e.embeddedObject();
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else if ( strcmp( "hint" , name ) == 0 )
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_hint = e;
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else if ( strcmp( "returnKey" , name ) == 0 )
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_returnKey = e.trueValue();
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else if ( strcmp( "maxScan" , name ) == 0 )
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_maxScan = e.numberInt();
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else if ( strcmp( "showDiskLoc" , name ) == 0 )
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_showDiskLoc = e.trueValue();
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else if ( strcmp( "comment" , name ) == 0 ) {
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; // no-op
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}
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}
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}
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if ( _snapshot ) {
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uassert( 12001 , "E12001 can't sort with $snapshot", _order.isEmpty() );
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uassert( 12002 , "E12002 can't use hint with $snapshot", _hint.eoo() );
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}
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}
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void initFields( const BSONObj& fields ) {
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if ( fields.isEmpty() )
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return;
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_fields.reset( new Projection() );
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_fields->init( fields );
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}
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const char * const _ns;
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const int _ntoskip;
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int _ntoreturn;
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BSONObj _filter;
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BSONObj _order;
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const int _options;
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shared_ptr< Projection > _fields;
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bool _wantMore;
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bool _explain;
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bool _snapshot;
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bool _returnKey;
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bool _showDiskLoc;
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BSONObj _min;
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BSONObj _max;
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BSONElement _hint;
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int _maxScan;
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};
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} // namespace mongo
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