This interface is a work in progress. More...

#include <sorted_data_interface.h>

Inheritance diagram for mongo::SortedDataInterface:

Detailed Description

This interface is a work in progress.

Notes below:

This interface began as the SortedDataInterface, a way to hide the fact that there were two on-disk formats for the btree. With the introduction of other storage engines, this interface was generalized to provide access to sorted data. Specifically:

Many other storage engines provide different Btree(-ish) implementations. This interface could allow those interfaces to avoid storing btree buckets in an already sorted structure.

TODO: See if there is actually a performance gain.

The existing btree implementation is written to assume that if it modifies a record it is modifying the underlying record. This interface is an attempt to work around that.

TODO: See if this actually works.

Classes
class	Cursor
	Navigates over the sorted data. More...

Public Member Functions
virtual	~SortedDataInterface ()

virtual SortedDataBuilderInterface *	getBulkBuilder (OperationContext *opCtx, bool dupsAllowed)=0
	Return a bulk builder for 'this' index. More...

virtual Status	insert (OperationContext *opCtx, const BSONObj &key, const RecordId &loc, bool dupsAllowed)=0
	Insert an entry into the index with the specified key and RecordId. More...

virtual void	unindex (OperationContext *opCtx, const BSONObj &key, const RecordId &loc, bool dupsAllowed)=0
	Remove the entry from the index with the specified key and RecordId. More...

virtual Status	dupKeyCheck (OperationContext *opCtx, const BSONObj &key, const RecordId &loc)=0
	Return ErrorCodes::DuplicateKey if 'key' already exists in 'this' index at a RecordId other than 'loc', and Status::OK() otherwise. More...

virtual Status	compact (OperationContext *opCtx)
	Attempt to reduce the storage space used by this index via compaction. More...

virtual void	fullValidate (OperationContext opCtx, long long numKeysOut, ValidateResults *fullResults) const =0
	TODO: expose full set of args for testing? More...

virtual bool	appendCustomStats (OperationContext opCtx, BSONObjBuilder output, double scale) const =0

virtual long long	getSpaceUsedBytes (OperationContext *opCtx) const =0
	Return the number of bytes consumed by 'this' index. More...

virtual bool	isEmpty (OperationContext *opCtx)=0
	Return true if 'this' index is empty, and false otherwise. More...

virtual Status	touch (OperationContext *opCtx) const
	Attempt to bring the entirety of 'this' index into memory. More...

virtual long long	numEntries (OperationContext *opCtx) const
	Return the number of entries in 'this' index. More...

virtual std::unique_ptr< Cursor >	newCursor (OperationContext *opCtx, bool isForward=true) const =0
	Returns an unpositioned cursor over 'this' index. More...

virtual std::unique_ptr< Cursor >	newRandomCursor (OperationContext *opCtx) const
	Constructs a cursor over an index that returns entries in a randomized order, and allows storage engines to provide a more efficient way to randomly sample a collection than MongoDB's default sampling methods, which are used when this method returns {}. More...

virtual Status	initAsEmpty (OperationContext *opCtx)=0

Constructor & Destructor Documentation

◆ ~SortedDataInterface()

virtual mongo::SortedDataInterface::~SortedDataInterface ( )

inlinevirtual

Member Function Documentation

◆ appendCustomStats()

virtual bool mongo::SortedDataInterface::appendCustomStats	(	OperationContext *	opCtx,
		BSONObjBuilder *	output,
		double	scale
	)		const

pure virtual

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ compact()

virtual Status mongo::SortedDataInterface::compact ( OperationContext * opCtx )

inlinevirtual

Attempt to reduce the storage space used by this index via compaction.

Only called if the indexed record store supports compaction-in-place.

Reimplemented in mongo::WiredTigerIndex.

◆ dupKeyCheck()

virtual Status mongo::SortedDataInterface::dupKeyCheck	(	OperationContext *	opCtx,
		const BSONObj &	key,
		const RecordId &	loc
	)

pure virtual

Return ErrorCodes::DuplicateKey if 'key' already exists in 'this' index at a RecordId other than 'loc', and Status::OK() otherwise.

Parameters

opCtx the transaction under which this operation takes place

TODO: Hide this by exposing an update method?

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ fullValidate()

virtual void mongo::SortedDataInterface::fullValidate	(	OperationContext *	opCtx,
		long long *	numKeysOut,
		ValidateResults *	fullResults
	)		const

pure virtual

TODO: expose full set of args for testing?

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ getBulkBuilder()

virtual SortedDataBuilderInterface* mongo::SortedDataInterface::getBulkBuilder	(	OperationContext *	opCtx,
		bool	dupsAllowed
	)

pure virtual

Return a bulk builder for 'this' index.

Implementations can assume that 'this' index outlives its bulk builder.

Parameters

opCtx	the transaction under which keys are added to 'this' index
dupsAllowed	true if duplicate keys are allowed, and false otherwise

Returns: caller takes ownership

Implemented in mongo::WiredTigerIndexStandard, mongo::WiredTigerIndexUnique, mongo::DevNullSortedDataInterface, mongo::MobileIndexUnique, and mongo::MobileIndexStandard.

◆ getSpaceUsedBytes()

virtual long long mongo::SortedDataInterface::getSpaceUsedBytes ( OperationContext * opCtx ) const

pure virtual

Return the number of bytes consumed by 'this' index.

Parameters

opCtx the transaction under which this operation takes place

See also: IndexAccessMethod::getSpaceUsedBytes

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ initAsEmpty()

virtual Status mongo::SortedDataInterface::initAsEmpty ( OperationContext * opCtx )

pure virtual

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ insert()

virtual Status mongo::SortedDataInterface::insert	(	OperationContext *	opCtx,
		const BSONObj &	key,
		const RecordId &	loc,
		bool	dupsAllowed
	)

pure virtual

Insert an entry into the index with the specified key and RecordId.

Parameters

opCtx	the transaction under which the insert takes place
dupsAllowed	true if duplicate keys are allowed, and false otherwise

Returns

Status::OK() if the insert succeeded,

    ErrorCodes::DuplicateKey if 'key' already exists in 'this' index
    at a RecordId other than 'loc' and duplicates were not allowed

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ isEmpty()

virtual bool mongo::SortedDataInterface::isEmpty ( OperationContext * opCtx )

pure virtual

Return true if 'this' index is empty, and false otherwise.

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

◆ newCursor()

virtual std::unique_ptr<Cursor> mongo::SortedDataInterface::newCursor	(	OperationContext *	opCtx,
		bool	isForward = `true`
	)		const

pure virtual

Returns an unpositioned cursor over 'this' index.

Implementations can assume that 'this' index outlives all cursors it produces.

Implemented in mongo::WiredTigerIndexStandard, mongo::DevNullSortedDataInterface, mongo::WiredTigerIndexUnique, mongo::MobileIndexUnique, and mongo::MobileIndexStandard.

◆ newRandomCursor()

virtual std::unique_ptr<Cursor> mongo::SortedDataInterface::newRandomCursor ( OperationContext * opCtx ) const

inlinevirtual

Constructs a cursor over an index that returns entries in a randomized order, and allows storage engines to provide a more efficient way to randomly sample a collection than MongoDB's default sampling methods, which are used when this method returns {}.

Note if it is possible to implement RecordStore::getRandomCursor(), that method is preferred, as it will return the entire document, whereas this method will only return the index key and the RecordId, requiring an extra lookup.

This method may be implemented using a pseudo-random walk over B-trees or a similar approach. Different cursors should return entries in a different order. Random cursors may return the same entry more than once and, as a result, may return more entries than exist in the index. Implementations should avoid obvious biases toward older, newer, larger smaller or other specific classes of entries.

◆ numEntries()

virtual long long mongo::SortedDataInterface::numEntries ( OperationContext * opCtx ) const

inlinevirtual

Return the number of entries in 'this' index.

The default implementation should be overridden with a more efficient one if at all possible.

Reimplemented in mongo::MobileIndex.

◆ touch()

virtual Status mongo::SortedDataInterface::touch ( OperationContext * opCtx ) const

inlinevirtual

Attempt to bring the entirety of 'this' index into memory.

If the underlying storage engine does not support the operation, returns ErrorCodes::CommandNotSupported

Returns: Status::OK()

Reimplemented in mongo::WiredTigerIndex.

◆ unindex()

virtual void mongo::SortedDataInterface::unindex	(	OperationContext *	opCtx,
		const BSONObj &	key,
		const RecordId &	loc,
		bool	dupsAllowed
	)

pure virtual

Remove the entry from the index with the specified key and RecordId.

Parameters

opCtx	the transaction under which the remove takes place
dupsAllowed	true if duplicate keys are allowed, and false otherwise

Implemented in mongo::DevNullSortedDataInterface, mongo::WiredTigerIndex, and mongo::MobileIndex.

The documentation for this class was generated from the following file:

/home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/sorted_data_interface.h

Detailed Description

Classes

Public Member Functions

Constructor & Destructor Documentation

◆ ~SortedDataInterface()

Member Function Documentation

◆ appendCustomStats()

◆ compact()

◆ dupKeyCheck()

◆ fullValidate()

◆ getBulkBuilder()

◆ getSpaceUsedBytes()

◆ initAsEmpty()

◆ insert()

◆ isEmpty()

◆ newCursor()

◆ newRandomCursor()

◆ numEntries()

◆ touch()

◆ unindex()