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diff --git a/src/mongo/db/key.h b/src/mongo/db/key.h
new file mode 100644
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+// @file key.h class(es) representing individual keys in a btree
+
+/**
+*    Copyright (C) 2011 10gen 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/>.
+*/
+
+#pragma once
+ 
+#include "jsobj.h"
+
+namespace mongo { 
+
+    /** Key class for precomputing a small format index key that is denser than a traditional BSONObj. 
+
+        KeyBson is a legacy wrapper implementation for old BSONObj style keys for v:0 indexes.
+
+        KeyV1 is the new implementation.
+    */
+    class KeyBson /* "KeyV0" */ { 
+    public:
+        KeyBson() { }
+        explicit KeyBson(const char *keyData) : _o(keyData) { }
+        explicit KeyBson(const BSONObj& obj) : _o(obj) { }
+        int woCompare(const KeyBson& r, const Ordering &o) const;
+        BSONObj toBson() const { return _o; }
+        string toString() const { return _o.toString(); }
+        int dataSize() const { return _o.objsize(); }
+        const char * data() const { return _o.objdata(); }
+        BSONElement _firstElement() const { return _o.firstElement(); }
+        bool isCompactFormat() const { return false; }
+        bool woEqual(const KeyBson& r) const;
+        void assign(const KeyBson& rhs) { *this = rhs; }
+    private:
+        BSONObj _o;
+    };
+
+    class KeyV1Owned;
+
+    // corresponding to BtreeData_V1
+    class KeyV1 { 
+        void operator=(const KeyV1&); // disallowed just to make people be careful as we don't own the buffer
+        KeyV1(const KeyV1Owned&);     // disallowed as this is not a great idea as KeyV1Owned likely will go out of scope
+    public:
+        KeyV1() { _keyData = 0; }
+        ~KeyV1() { DEV _keyData = (const unsigned char *) 1; }
+
+        KeyV1(const KeyV1& rhs) : _keyData(rhs._keyData) { 
+            dassert( _keyData > (const unsigned char *) 1 );
+        }
+
+        // explicit version of operator= to be safe
+        void assign(const KeyV1& rhs) { 
+            _keyData = rhs._keyData;
+        }
+
+        /** @param keyData can be a buffer containing data in either BSON format, OR in KeyV1 format. 
+                   when BSON, we are just a wrapper
+        */
+        explicit KeyV1(const char *keyData) : _keyData((unsigned char *) keyData) { }
+
+        int woCompare(const KeyV1& r, const Ordering &o) const;
+        bool woEqual(const KeyV1& r) const;
+        BSONObj toBson() const;
+        string toString() const { return toBson().toString(); }
+
+        /** get the key data we want to store in the btree bucket */
+        const char * data() const { return (const char *) _keyData; }
+
+        /** @return size of data() */
+        int dataSize() const;
+
+        /** only used by geo, which always has bson keys */
+        BSONElement _firstElement() const { return bson().firstElement(); }
+        bool isCompactFormat() const { return *_keyData != IsBSON; }
+    protected:
+        enum { IsBSON = 0xff };
+        const unsigned char *_keyData;
+        BSONObj bson() const {
+            dassert( !isCompactFormat() );
+            return BSONObj((const char *) _keyData+1);
+        }
+    private:
+        int compareHybrid(const KeyV1& right, const Ordering& order) const;
+    };
+
+    class KeyV1Owned : public KeyV1 { 
+        void operator=(const KeyV1Owned&);
+    public:
+        /** @obj a BSON object to be translated to KeyV1 format.  If the object isn't 
+                 representable in KeyV1 format (which happens, intentionally, at times)
+                 it will stay as bson herein.
+        */
+        KeyV1Owned(const BSONObj& obj);
+
+        /** makes a copy (memcpy's the whole thing) */
+        KeyV1Owned(const KeyV1& rhs);
+
+    private:
+        StackBufBuilder b;
+        void traditional(const BSONObj& obj); // store as traditional bson not as compact format
+    };
+
+};