The struct 'lob::ref_t' represents an external field reference. More...

#include <lob0lob.h>

Public Member Functions
	ref_t (byte *ptr)
	Constructor. More...

bool	use_single_z_stream () const
	For compressed LOB, if the length is less than or equal to Z_CHUNK_SIZE then use the older single z stream format to store the LOB. More...

bool	is_big (const page_size_t &page_size) const
	Check if this LOB is big enough to do partial update. More...

void	parse (ref_mem_t &obj) const
	Parse the LOB reference object and copy data into the given ref_mem_t object. More...

void	copy (byte *field_ref) const
	Copy the LOB reference into the given memory location. More...

bool	is_equal (const byte *ptr) const
	Check whether the stored external field reference is equal to the given field reference. More...

void	set_ref (byte *ptr)
	Set the external field reference to the given memory location. More...

bool	is_null_relaxed () const
	Check if the field reference is made of zeroes except the being_modified bit. More...

bool	is_null () const
	Check if the field reference is made of zeroes. More...

void	set_owner (bool owner, mtr_t *mtr)
	Set the ownership flag in the blob reference. More...

void	set_being_modified (bool modifying, mtr_t *mtr)
	Set the being_modified flag in the field reference. More...

bool	is_being_modified () const
	Check if the current blob is being modified. More...

void	set_inherited (bool inherited, mtr_t *mtr)
	Set the inherited flag in the field reference. More...

bool	is_owner () const
	Check if the current row is the owner of the blob. More...

bool	is_inherited () const
	Check if the current row inherited the blob from parent row. More...

space_id_t	space_id () const
	Read the space id from the blob reference. More...

page_no_t	page_no () const
	Read the page number from the blob reference. More...

ulint	offset () const
	Read the offset of blob header from the blob reference. More...

uint32_t	version () const
	Read the LOB version from the blob reference. More...

ulint	length () const
	Read the length from the blob reference. More...

void	update (space_id_t space_id, ulint page_no, ulint offset, mtr_t *mtr)
	Update the information stored in the external field reference. More...

void	set_space_id (const space_id_t space_id, mtr_t *mtr)
	Set the space_id in the external field reference. More...

void	set_page_no (const ulint page_no, mtr_t *mtr)
	Set the page number in the external field reference. More...

void	set_offset (const ulint offset, mtr_t *mtr)
	Set the offset information in the external field reference. More...

void	set_length (const ulint len, mtr_t *mtr)
	Set the length of blob in the external field reference. More...

page_t *	page_align () const
	Get the start of a page containing this blob reference. More...

bool	validate (mtr_t *mtr)
	Check if the given mtr has necessary latches to update this LOB reference. More...

bool	check_space_id (dict_index_t *index) const
	Check if the space_id in the LOB reference is equal to the space_id of the index to which it belongs. More...

bool	is_lob_partially_updatable (const dict_index_t *index) const
	Check if the LOB can be partially updated. More...

void	mark_not_partially_updatable (trx_t trx, mtr_t mtr, dict_index_t *index, const page_size_t &page_size)
	Load the first page of the LOB and mark it as not partially updatable anymore. More...

ulint	get_lob_page_info (const dict_index_t *index, const page_size_t &page_size, bool &is_partially_updatable) const
	Load the first page of LOB and read its page type. More...

std::ostream &	print (std::ostream &out) const
	Print this LOB reference into the given output stream. More...

Static Public Member Functions
static bool	use_single_z_stream (ulint len)
	For compressed LOB, if the length is less than or equal to Z_CHUNK_SIZE then use the older single z stream format to store the LOB. More...

static bool	is_big (const page_size_t &page_size, const ulint lob_length)
	Check if this LOB is big enough to do partial update. More...

static bool	is_null_relaxed (const byte *ref)
	Check if the LOB reference is null (all zeroes) except the "is being modified" bit. More...

static bool	is_null (const byte *ref)
	Check if the LOB reference is null (all zeroes). More...

static void	set_being_modified (byte ref, bool modifying, mtr_t mtr)
	Set the being_modified flag in the field reference. More...

static bool	is_being_modified (const byte *field_ref)
	Check if the current blob is being modified. More...

static space_id_t	space_id (const byte *ref)
	Read the space id from the given blob reference. More...

static page_no_t	page_no (const byte *ref)
	Read the page no from the blob reference. More...

Static Public Attributes
static const ulint	LOB_SMALL_CHANGE_THRESHOLD = 100
	If the total number of bytes modified in an LOB, in an update operation, is less than or equal to this threshold LOB_SMALL_CHANGE_THRESHOLD, then it is considered as a small change. More...

static const uint	SIZE = BTR_EXTERN_FIELD_REF_SIZE
	The size of an LOB reference object (in bytes) More...

Private Attributes
byte *	m_ref
	Pointing to a memory of size BTR_EXTERN_FIELD_REF_SIZE. More...

Static Private Attributes
static const ulint	LOB_BIG_THRESHOLD_SIZE = 2
	If the LOB size is equal to or above this limit (in physical page size terms), then the LOB is big enough to be partially updated. More...

Detailed Description

The struct 'lob::ref_t' represents an external field reference.

The reference in a field for which data is stored on a different page. The reference is at the end of the 'locally' stored part of the field. 'Locally' means storage in the index record. We store locally a long enough prefix of each column so that we can determine the ordering parts of each index record without looking into the externally stored part.

Constructor & Destructor Documentation

◆ ref_t()

lob::ref_t::ref_t ( byte * ptr )

inlineexplicit

Constructor.

Parameters

[in] ptr Pointer to the external field reference.

Member Function Documentation

◆ check_space_id()

bool lob::ref_t::check_space_id ( dict_index_t * index ) const

Check if the space_id in the LOB reference is equal to the space_id of the index to which it belongs.

Parameters

[in] index the index to which LOB belongs.

Returns: true if space is valid in LOB reference, false otherwise.

◆ copy()

void lob::ref_t::copy ( byte * field_ref ) const

inline

Copy the LOB reference into the given memory location.

Parameters

[out] field_ref write LOB reference in this location.

◆ get_lob_page_info()

ulint lob::ref_t::get_lob_page_info	(	const dict_index_t *	index,
		const page_size_t &	page_size,
		bool &	is_partially_updatable
	)		const

Load the first page of LOB and read its page type.

Parameters

[in]	index	the index object.
[in]	page_size	the page size of LOB.
[out]	is_partially_updatable	is the LOB partially updatable.

Returns: the page type of first page of LOB.

◆ is_being_modified() [1/2]

bool lob::ref_t::is_being_modified ( ) const

inline

Check if the current blob is being modified.

Returns: true if it is being modified, false otherwise.

◆ is_being_modified() [2/2]

static bool lob::ref_t::is_being_modified ( const byte * field_ref )

inlinestatic

Check if the current blob is being modified.

Parameters

[in] field_ref blob field reference

Returns: true if it is being modified, false otherwise.

◆ is_big() [1/2]

bool lob::ref_t::is_big ( const page_size_t & page_size ) const

inline

Check if this LOB is big enough to do partial update.

Parameters

[in] page_size the page size

Returns: true if LOB is big enough, false otherwise.

◆ is_big() [2/2]

static bool lob::ref_t::is_big	(	const page_size_t &	page_size,
		const ulint	lob_length
	)

inlinestatic

Check if this LOB is big enough to do partial update.

Parameters

[in]	page_size	the page size
[in]	lob_length	the size of BLOB in bytes.

Returns: true if LOB is big enough, false otherwise.

◆ is_equal()

bool lob::ref_t::is_equal ( const byte * ptr ) const

inline

Check whether the stored external field reference is equal to the given field reference.

Parameters

[in] ptr supplied external field reference.

◆ is_inherited()

bool lob::ref_t::is_inherited ( ) const

inline

Check if the current row inherited the blob from parent row.

Returns: true if inherited, false otherwise.

◆ is_lob_partially_updatable()

bool lob::ref_t::is_lob_partially_updatable ( const dict_index_t * index ) const

Check if the LOB can be partially updated.

This is done by loading the first page of LOB and looking at the flags.

Parameters

[in] index the index to which LOB belongs.

Returns: true if LOB is partially updatable, false otherwise.

◆ is_null() [1/2]

bool lob::ref_t::is_null ( ) const

inline

Check if the field reference is made of zeroes.

Returns: true if field reference is made of zeroes, false otherwise.

◆ is_null() [2/2]

static bool lob::ref_t::is_null ( const byte * ref )

inlinestatic

Check if the LOB reference is null (all zeroes).

Parameters

[in] ref the LOB reference.

Returns: true if the LOB reference is null (all zeros), false otherwise.

◆ is_null_relaxed() [1/2]

bool lob::ref_t::is_null_relaxed ( ) const

inline

Check if the field reference is made of zeroes except the being_modified bit.

Returns: true if field reference is made of zeroes, false otherwise.

◆ is_null_relaxed() [2/2]

static bool lob::ref_t::is_null_relaxed ( const byte * ref )

inlinestatic

Check if the LOB reference is null (all zeroes) except the "is being modified" bit.

Parameters

[in] ref the LOB reference.

Returns: true if the LOB reference is null (all zeros) except the "is being modified" bit, false otherwise.

◆ is_owner()

bool lob::ref_t::is_owner ( ) const

inline

Check if the current row is the owner of the blob.

Returns: true if owner, false otherwise.

◆ length()

ulint lob::ref_t::length ( ) const

inline

Read the length from the blob reference.

Returns: length of the blob

◆ mark_not_partially_updatable()

void lob::ref_t::mark_not_partially_updatable	(	trx_t *	trx,
		mtr_t *	mtr,
		dict_index_t *	index,
		const page_size_t &	page_size
	)

Load the first page of the LOB and mark it as not partially updatable anymore.

Parameters

[in]	trx	Current transaction
[in]	mtr	Mini-transaction context.
[in]	index	Index dictionary object.
[in]	page_size	Page size information.

◆ offset()

ulint lob::ref_t::offset ( ) const

inline

Read the offset of blob header from the blob reference.

Returns: the offset of the blob header

◆ page_align()

page_t * lob::ref_t::page_align ( ) const

inline

Get the start of a page containing this blob reference.

Returns: start of the page

◆ page_no() [1/2]

page_no_t lob::ref_t::page_no ( ) const

inline

Read the page number from the blob reference.

Returns: the page number

◆ page_no() [2/2]

static page_no_t lob::ref_t::page_no ( const byte * ref )

inlinestatic

Read the page no from the blob reference.

Returns: the page no

◆ parse()

void lob::ref_t::parse ( ref_mem_t & obj ) const

inline

Parse the LOB reference object and copy data into the given ref_mem_t object.

Parameters

[out] obj LOB reference memory object.

◆ print()

std::ostream & lob::ref_t::print ( std::ostream & out ) const

Print this LOB reference into the given output stream.

Parameters

[in] out the output stream.

Returns: the output stream.

◆ set_being_modified() [1/2]

void lob::ref_t::set_being_modified	(	bool	modifying,
		mtr_t *	mtr
	)

inline

Set the being_modified flag in the field reference.

Parameters

[in]	modifying	true, if blob is being modified.
[in]	mtr	Mini-transaction context.

◆ set_being_modified() [2/2]

static void lob::ref_t::set_being_modified	(	byte *	ref,
		bool	modifying,
		mtr_t *	mtr
	)

inlinestatic

Set the being_modified flag in the field reference.

Parameters

[in,out]	ref	The LOB reference
[in]	modifying	true, if blob is being modified.
[in]	mtr	Mini-transaction context.

◆ set_inherited()

void lob::ref_t::set_inherited	(	bool	inherited,
		mtr_t *	mtr
	)

inline

Set the inherited flag in the field reference.

Parameters

[in]	inherited	true, if inherited.
[in]	mtr	Mini-transaction context.

◆ set_length()

void lob::ref_t::set_length	(	const ulint	len,
		mtr_t *	mtr
	)

inline

Set the length of blob in the external field reference.

Parameters

[in]	len	the blob length .
[in]	mtr	mini-trx or NULL.

◆ set_offset()

void lob::ref_t::set_offset	(	const ulint	offset,
		mtr_t *	mtr
	)

inline

Set the offset information in the external field reference.

Parameters

[in]	offset	the offset.
[in]	mtr	mini-trx or NULL.

◆ set_owner()

void lob::ref_t::set_owner	(	bool	owner,
		mtr_t *	mtr
	)

inline

Set the ownership flag in the blob reference.

Parameters

[in]	owner	Whether to own or disown. If owner, unset the owner flag.
[in]	mtr	Mini-transaction or NULL.

◆ set_page_no()

void lob::ref_t::set_page_no	(	const ulint	page_no,
		mtr_t *	mtr
	)

inline

Set the page number in the external field reference.

Parameters

[in]	page_no	the page number.
[in]	mtr	mini-trx or NULL.

◆ set_ref()

void lob::ref_t::set_ref ( byte * ptr )

inline

Set the external field reference to the given memory location.

Parameters

[in] ptr the new external field reference.

◆ set_space_id()

void lob::ref_t::set_space_id	(	const space_id_t	space_id,
		mtr_t *	mtr
	)

inline

Set the space_id in the external field reference.

Parameters

[in]	space_id	the space identifier.
[in]	mtr	mini-trx or NULL.

◆ space_id() [1/2]

space_id_t lob::ref_t::space_id ( ) const

inline

Read the space id from the blob reference.

Returns: the space id

◆ space_id() [2/2]

static space_id_t lob::ref_t::space_id ( const byte * ref )

inlinestatic

Read the space id from the given blob reference.

Parameters

[in] ref the blob reference.

Returns: the space id

◆ update()

void lob::ref_t::update	(	space_id_t	space_id,
		ulint	page_no,
		ulint	offset,
		mtr_t *	mtr
	)

inline

Update the information stored in the external field reference.

Parameters

[in]	space_id	the space identifier.
[in]	page_no	the page number.
[in]	offset	the offset within the page_no
[in]	mtr	the mini trx or NULL.

◆ use_single_z_stream() [1/2]

bool lob::ref_t::use_single_z_stream ( ) const

inline

For compressed LOB, if the length is less than or equal to Z_CHUNK_SIZE then use the older single z stream format to store the LOB.

◆ use_single_z_stream() [2/2]

static bool lob::ref_t::use_single_z_stream ( ulint len )

inlinestatic

For compressed LOB, if the length is less than or equal to Z_CHUNK_SIZE then use the older single z stream format to store the LOB.

◆ validate()

bool lob::ref_t::validate ( mtr_t * mtr )

inline

Check if the given mtr has necessary latches to update this LOB reference.

Parameters

[in] mtr Mini-transaction that needs to be checked.

Returns: true if valid, false otherwise.

◆ version()

uint32_t lob::ref_t::version ( ) const

inline

Read the LOB version from the blob reference.

Returns: the LOB version number.

Member Data Documentation

◆ LOB_BIG_THRESHOLD_SIZE

const ulint lob::ref_t::LOB_BIG_THRESHOLD_SIZE = 2

staticprivate

If the LOB size is equal to or above this limit (in physical page size terms), then the LOB is big enough to be partially updated.

Only in this case LOB index needs to be built.

◆ LOB_SMALL_CHANGE_THRESHOLD

const ulint lob::ref_t::LOB_SMALL_CHANGE_THRESHOLD = 100

static

If the total number of bytes modified in an LOB, in an update operation, is less than or equal to this threshold LOB_SMALL_CHANGE_THRESHOLD, then it is considered as a small change.

For small changes to LOB, the changes are undo logged like any other update operation.

◆ m_ref

byte* lob::ref_t::m_ref

private

Pointing to a memory of size BTR_EXTERN_FIELD_REF_SIZE.

◆ SIZE

const uint lob::ref_t::SIZE = BTR_EXTERN_FIELD_REF_SIZE

static

The size of an LOB reference object (in bytes)

The documentation for this struct was generated from the following files:

storage/innobase/include/lob0lob.h
storage/innobase/lob/lob0lob.cc

Public Member Functions

Static Public Member Functions

Static Public Attributes

Private Attributes

Static Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ref_t()

Member Function Documentation

◆ check_space_id()

◆ copy()

◆ get_lob_page_info()

◆ is_being_modified() [1/2]

◆ is_being_modified() [2/2]

◆ is_big() [1/2]

◆ is_big() [2/2]

◆ is_equal()

◆ is_inherited()

◆ is_lob_partially_updatable()

◆ is_null() [1/2]

◆ is_null() [2/2]

◆ is_null_relaxed() [1/2]

◆ is_null_relaxed() [2/2]

◆ is_owner()

◆ length()

◆ mark_not_partially_updatable()

◆ offset()

◆ page_align()

◆ page_no() [1/2]

◆ page_no() [2/2]

◆ parse()

◆ print()

◆ set_being_modified() [1/2]

◆ set_being_modified() [2/2]

◆ set_inherited()

◆ set_length()

◆ set_offset()

◆ set_owner()

◆ set_page_no()

◆ set_ref()

◆ set_space_id()

◆ space_id() [1/2]

◆ space_id() [2/2]

◆ update()

◆ use_single_z_stream() [1/2]

◆ use_single_z_stream() [2/2]

◆ validate()

◆ version()

Member Data Documentation

◆ LOB_BIG_THRESHOLD_SIZE

◆ LOB_SMALL_CHANGE_THRESHOLD

◆ m_ref

◆ SIZE