Rollback segment. More...

#include <vector>
#include "fut0lst.h"
#include "trx0sys.h"
#include "trx0types.h"
#include "univ.i"
#include "trx0rseg.ic"

Macros
#define	TRX_RSEG_N_SLOTS (UNIV_PAGE_SIZE / 16)
	Number of undo log slots in a rollback segment file copy. More...

#define	TRX_RSEG_MAX_N_TRXS (TRX_RSEG_N_SLOTS / 2)
	Maximum number of transactions supported by a single rollback segment. More...

#define	TRX_RSEG_SLOT_END (TRX_RSEG_UNDO_SLOTS + TRX_RSEG_SLOT_SIZE * TRX_RSEG_N_SLOTS)
	End of undo slots in rollback segment page. More...

#define	TRX_RSEG_MAX_TRX_NO TRX_RSEG_SLOT_END

Functions
static trx_rsegf_t *	trx_rsegf_get (space_id_t space, page_no_t page_no, const page_size_t &page_size, mtr_t *mtr)
	Gets a rollback segment header. More...

static trx_rsegf_t *	trx_rsegf_get_new (space_id_t space, page_no_t page_no, const page_size_t &page_size, mtr_t *mtr)
	Gets a newly created rollback segment header. More...

static page_no_t	trx_rsegf_get_nth_undo (trx_rsegf_t rsegf, ulint n, mtr_t mtr)
	Gets the file page number of the nth undo log slot. More...

static void	trx_rsegf_set_nth_undo (trx_rsegf_t rsegf, ulint n, page_no_t page_no, mtr_t mtr)
	Sets the file page number of the nth undo log slot. More...

static ulint	trx_rsegf_undo_find_free (trx_rsegf_t rsegf, mtr_t mtr)
	Looks for a free slot for an undo log segment. More...

page_no_t	trx_rseg_header_create (space_id_t space_id, const page_size_t &page_size, page_no_t max_size, ulint rseg_slot, mtr_t *mtr)
	Creates a rollback segment header. More...

bool	trx_rseg_adjust_rollback_segments (ulong target_rollback_segments)
	Add more rsegs to the rseg list in each tablespace until there are srv_rollback_segments of them. More...

bool	trx_rseg_init_rollback_segments (space_id_t space_id, ulong target_rollback_segments)
	Create the requested number of Rollback Segments in a newly created undo tablespace and add them to the Rsegs object. More...

void	trx_rsegs_init (purge_pq_t *purge_queue)
	Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY page of each undo tablespace. More...

void	trx_rsegs_parallel_init (purge_pq_t *purge_queue)
	Initialize rollback segments in parallel. More...

trx_rseg_t *	trx_rseg_mem_create (ulint id, space_id_t space_id, page_no_t page_no, const page_size_t &page_size, trx_id_t gtid_trx_no, purge_pq_t purge_queue, mtr_t mtr)
	Create and initialize a rollback segment object. More...

page_no_t	trx_rseg_create (space_id_t space_id, ulint rseg_id)
	Create a rollback segment in the given tablespace. More...

void	trx_rseg_get_n_undo_tablespaces (Space_Ids *spaces_to_open)
	Build a list of unique undo tablespaces found in the TRX_SYS page. More...

void	trx_rseg_upgrade_undo_tablespaces ()
	Upgrade the TRX_SYS page so that it no longer tracks rsegs in undo tablespaces other than the system tablespace. More...

void	trx_rseg_array_create (space_id_t space_id, mtr_t *mtr)
	Create the file page for the rollback segment directory in an undo tablespace. More...

static void	trx_rsegsf_set_page_no (trx_rsegsf_t rsegs_header, ulint slot, page_no_t page_no, mtr_t mtr)
	Sets the page number of the nth rollback segment slot in the independent undo tablespace. More...

Variables
constexpr uint32_t	TRX_RSEG_SLOT_PAGE_NO = 0
	Page number of the header page of an undo log segment. More...

constexpr uint32_t	TRX_RSEG_SLOT_SIZE = 4
	Slot size. More...

constexpr uint32_t	TRX_RSEG = FSEG_PAGE_DATA
	The offset of the rollback segment header on its page. More...

constexpr uint32_t	TRX_RSEG_MAX_SIZE = 0
	Maximum allowed size for rollback segment in pages. More...

constexpr uint32_t	TRX_RSEG_HISTORY_SIZE = 4
	Number of file pages occupied by the logs in the history list. More...

constexpr uint32_t	TRX_RSEG_HISTORY = 8

constexpr uint32_t	TRX_RSEG_FSEG_HEADER = 8 + FLST_BASE_NODE_SIZE

constexpr uint32_t	TRX_RSEG_UNDO_SLOTS
	Undo log segment slots. More...

constexpr uint32_t	RSEG_ARRAY_HEADER = FSEG_PAGE_DATA
	The offset of the Rollback Segment Directory header on an RSEG_ARRAY page. More...

constexpr uint32_t	RSEG_ARRAY_VERSION = 0x52534547 + 1
	Rollback Segment Array Header. More...

constexpr uint32_t	RSEG_ARRAY_VERSION_OFFSET = 0
	The RSEG ARRAY version offset in the header. More...

constexpr uint32_t	RSEG_ARRAY_SIZE_OFFSET = 4
	The current number of rollback segments being tracked in this array. More...

constexpr uint32_t	RSEG_ARRAY_FSEG_HEADER_OFFSET = 8
	This is the pointer to the file segment inode that tracks this rseg array page. More...

constexpr uint32_t	RSEG_ARRAY_PAGES_OFFSET = 8 + FSEG_HEADER_SIZE
	The start of the array of rollback segment header page numbers for this undo tablespace. More...

constexpr uint32_t	RSEG_ARRAY_RESERVED_BYTES = 200
	Reserved space at the end of an RSEG_ARRAY page reserved for future use. More...

constexpr uint32_t	RSEG_ARRAY_SLOT_SIZE = 4

Detailed Description

Rollback segment.

Created 3/26/1996 Heikki Tuuri

Macro Definition Documentation

◆ TRX_RSEG_MAX_N_TRXS

#define TRX_RSEG_MAX_N_TRXS (TRX_RSEG_N_SLOTS / 2)

Maximum number of transactions supported by a single rollback segment.

◆ TRX_RSEG_MAX_TRX_NO

#define TRX_RSEG_MAX_TRX_NO TRX_RSEG_SLOT_END

◆ TRX_RSEG_N_SLOTS

#define TRX_RSEG_N_SLOTS (UNIV_PAGE_SIZE / 16)

Number of undo log slots in a rollback segment file copy.

◆ TRX_RSEG_SLOT_END

#define TRX_RSEG_SLOT_END (TRX_RSEG_UNDO_SLOTS + TRX_RSEG_SLOT_SIZE * TRX_RSEG_N_SLOTS)

End of undo slots in rollback segment page.

Function Documentation

◆ trx_rseg_adjust_rollback_segments()

bool trx_rseg_adjust_rollback_segments ( ulong target_rollback_segments )

Add more rsegs to the rseg list in each tablespace until there are srv_rollback_segments of them.

Use any rollback segment that already exists so that the purge_queue can be filled and processed with any existing undo log. If the rollback segments do not exist in this tablespace and we need them according to target_rollback_segments, then build them in the tablespace.

Parameters

[in] target_rollback_segments new number of rollback segments per space

Returns: true if all necessary rollback segments and trx_rseg_t objects were created.

The number of rollback segments created in the datafile.

◆ trx_rseg_array_create()

void trx_rseg_array_create	(	space_id_t	space_id,
		mtr_t *	mtr
	)

Create the file page for the rollback segment directory in an undo tablespace.

This function is called just after an undo tablespace is created so the next page created here should by FSP_FSEG_DIR_PAGE_NUM.

Parameters

[in]	space_id	Undo Tablespace ID
[in]	mtr	mtr

◆ trx_rseg_create()

page_no_t trx_rseg_create	(	space_id_t	space_id,
		ulint	rseg_id
	)

Create a rollback segment in the given tablespace.

This could be either the system tablespace, the temporary tablespace, or an undo tablespace.

Parameters

[in]	space_id	tablespace to get the rollback segment
[in]	rseg_id	slot number of the rseg within this tablespace

Returns: page number of the rollback segment header page created

◆ trx_rseg_get_n_undo_tablespaces()

void trx_rseg_get_n_undo_tablespaces ( Space_Ids * spaces_to_open )

Build a list of unique undo tablespaces found in the TRX_SYS page.

Do not count the system tablespace. The vector will be sorted on space id.

Parameters

[in,out] spaces_to_open list of undo tablespaces found.

◆ trx_rseg_header_create()

page_no_t trx_rseg_header_create	(	space_id_t	space_id,
		const page_size_t &	page_size,
		page_no_t	max_size,
		ulint	rseg_slot,
		mtr_t *	mtr
	)

Creates a rollback segment header.

This function is called only when a new rollback segment is created in the database.

Parameters

[in]	space_id	Space id
[in]	page_size	Page size
[in]	max_size	Max size in pages
[in]	rseg_slot	Rseg id == slot number in RSEG_ARRAY
[in,out]	mtr	Mini-transaction

Returns: page number of the created segment, FIL_NULL if fail

◆ trx_rseg_init_rollback_segments()

bool trx_rseg_init_rollback_segments	(	space_id_t	space_id,
		ulong	target_rollback_segments
	)

Create the requested number of Rollback Segments in a newly created undo tablespace and add them to the Rsegs object.

Parameters

[in]	space_id	undo tablespace ID
[in]	target_rollback_segments	number of rollback segments per space

Returns: true if all necessary rollback segments and trx_rseg_t objects were created.

The number of rollback segments created in the datafile.

◆ trx_rseg_mem_create()

trx_rseg_t * trx_rseg_mem_create	(	ulint	id,
		space_id_t	space_id,
		page_no_t	page_no,
		const page_size_t &	page_size,
		trx_id_t	gtid_trx_no,
		purge_pq_t *	purge_queue,
		mtr_t *	mtr
	)

Create and initialize a rollback segment object.

Some of the values for the fields are read from the segment header page. The caller must insert it into the correct list.

Parameters

[in]	id	Rollback segment id
[in]	space_id	Space where the segment is placed
[in]	page_no	Page number of the segment header
[in]	page_size	Page size
[in]	gtid_trx_no	Trx number up to which GTID is persisted
[in,out]	purge_queue	Rseg queue
[in,out]	mtr	Mini-transaction

Returns: own: rollback segment object

◆ trx_rseg_upgrade_undo_tablespaces()

void trx_rseg_upgrade_undo_tablespaces ( )

Upgrade the TRX_SYS page so that it no longer tracks rsegs in undo tablespaces other than the system tablespace.

Add these tablespaces to undo::spaces and put FIL_NULL in the slots in TRX_SYS.

Upgrade the TRX_SYS page so that it no longer tracks rsegs in undo tablespaces other than the system tablespace.

It should only track rollback segments in the system tablespace. Put FIL_NULL in the slots in TRX_SYS. Latch protection is not needed since this is during single-threaded startup.

◆ trx_rsegf_get()

static trx_rsegf_t * trx_rsegf_get	(	space_id_t	space,
		page_no_t	page_no,
		const page_size_t &	page_size,
		mtr_t *	mtr
	)

inlinestatic

Gets a rollback segment header.

Parameters

[in]	space	Space where placed
[in]	page_no	Page number of the header
[in]	page_size	Page size
[in,out]	mtr	Mini-transaction

Returns: rollback segment header, page x-latched

◆ trx_rsegf_get_new()

static trx_rsegf_t * trx_rsegf_get_new	(	space_id_t	space,
		page_no_t	page_no,
		const page_size_t &	page_size,
		mtr_t *	mtr
	)

inlinestatic

Gets a newly created rollback segment header.

Parameters

[in]	space	Space where placed
[in]	page_no	Page number of the header
[in]	page_size	Page size
[in,out]	mtr	Mini-transaction

Returns: rollback segment header, page x-latched

◆ trx_rsegf_get_nth_undo()

static page_no_t trx_rsegf_get_nth_undo	(	trx_rsegf_t *	rsegf,
		ulint	n,
		mtr_t *	mtr
	)

inlinestatic

Gets the file page number of the nth undo log slot.

Parameters

[in]	rsegf	rollback segment header
[in]	n	index of slot
[in]	mtr	mtr

Returns: page number of the undo log segment

◆ trx_rsegf_set_nth_undo()

static void trx_rsegf_set_nth_undo	(	trx_rsegf_t *	rsegf,
		ulint	n,
		page_no_t	page_no,
		mtr_t *	mtr
	)

inlinestatic

Sets the file page number of the nth undo log slot.

Parameters

[in]	rsegf	rollback segment header
[in]	n	index of slot
[in]	page_no	page number of the undo log segment
[in]	mtr	mtr

◆ trx_rsegf_undo_find_free()

static ulint trx_rsegf_undo_find_free	(	trx_rsegf_t *	rsegf,
		mtr_t *	mtr
	)

inlinestatic

Looks for a free slot for an undo log segment.

Parameters

[in]	rsegf	rollback segment header
[in]	mtr	mtr

Returns: slot index or ULINT_UNDEFINED if not found

◆ trx_rsegs_init()

void trx_rsegs_init ( purge_pq_t * purge_queue )

Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY page of each undo tablespace.

Create trx_rseg_t objects for all rollback segments found. This runs at database startup and initializes the in-memory lists of trx_rseg_t objects. We need to look at all slots in TRX_SYS and each RSEG_ARRAY page because we need to look for any existing undo log that may need to be recovered by purge. No latch is needed since this is still single-threaded startup. If we find existing rseg slots in TRX_SYS page that reference undo tablespaces and have active undo logs, then quit. They require an upgrade of undo tablespaces and that cannot happen with active undo logs.

Parameters

[in] purge_queue queue of rsegs to purge

◆ trx_rsegs_parallel_init()

void trx_rsegs_parallel_init ( purge_pq_t * purge_queue )

Initialize rollback segments in parallel.

Parameters

[in] purge_queue queue of rsegs to purge

Parameters

purge_queue in: rseg queue

◆ trx_rsegsf_set_page_no()

static void trx_rsegsf_set_page_no	(	trx_rsegsf_t *	rsegs_header,
		ulint	slot,
		page_no_t	page_no,
		mtr_t *	mtr
	)

inlinestatic

Sets the page number of the nth rollback segment slot in the independent undo tablespace.

Parameters

[in]	rsegs_header	rollback segment array page header
[in]	slot	slot number on page == rseg id
[in]	page_no	rollback regment header page number
[in]	mtr	mtr

Variable Documentation

◆ RSEG_ARRAY_FSEG_HEADER_OFFSET

constexpr uint32_t RSEG_ARRAY_FSEG_HEADER_OFFSET = 8

constexpr

This is the pointer to the file segment inode that tracks this rseg array page.

◆ RSEG_ARRAY_HEADER

constexpr uint32_t RSEG_ARRAY_HEADER = FSEG_PAGE_DATA

constexpr

The offset of the Rollback Segment Directory header on an RSEG_ARRAY page.

◆ RSEG_ARRAY_PAGES_OFFSET

constexpr uint32_t RSEG_ARRAY_PAGES_OFFSET = 8 + FSEG_HEADER_SIZE

constexpr

The start of the array of rollback segment header page numbers for this undo tablespace.

The potential size of this array is limited only by the page size minus overhead. The actual size of the array is limited by srv_rollback_segments.

◆ RSEG_ARRAY_RESERVED_BYTES

constexpr uint32_t RSEG_ARRAY_RESERVED_BYTES = 200

constexpr

Reserved space at the end of an RSEG_ARRAY page reserved for future use.

◆ RSEG_ARRAY_SIZE_OFFSET

constexpr uint32_t RSEG_ARRAY_SIZE_OFFSET = 4

constexpr

The current number of rollback segments being tracked in this array.

◆ RSEG_ARRAY_SLOT_SIZE

constexpr uint32_t RSEG_ARRAY_SLOT_SIZE = 4

constexpr

◆ RSEG_ARRAY_VERSION

constexpr uint32_t RSEG_ARRAY_VERSION = 0x52534547 + 1

constexpr

Rollback Segment Array Header.

The RSEG ARRAY base version is a number derived from the string 'RSEG' [0x 52 53 45 47] for extra validation. Each new version increments the base version by 1.

◆ RSEG_ARRAY_VERSION_OFFSET

constexpr uint32_t RSEG_ARRAY_VERSION_OFFSET = 0

constexpr

The RSEG ARRAY version offset in the header.

◆ TRX_RSEG

constexpr uint32_t TRX_RSEG = FSEG_PAGE_DATA

constexpr

The offset of the rollback segment header on its page.

◆ TRX_RSEG_FSEG_HEADER

constexpr uint32_t TRX_RSEG_FSEG_HEADER = 8 + FLST_BASE_NODE_SIZE

constexpr

◆ TRX_RSEG_HISTORY

constexpr uint32_t TRX_RSEG_HISTORY = 8

constexpr

◆ TRX_RSEG_HISTORY_SIZE

constexpr uint32_t TRX_RSEG_HISTORY_SIZE = 4

constexpr

Number of file pages occupied by the logs in the history list.

◆ TRX_RSEG_MAX_SIZE

constexpr uint32_t TRX_RSEG_MAX_SIZE = 0

constexpr

Maximum allowed size for rollback segment in pages.

◆ TRX_RSEG_SLOT_PAGE_NO

constexpr uint32_t TRX_RSEG_SLOT_PAGE_NO = 0

constexpr

Page number of the header page of an undo log segment.

◆ TRX_RSEG_SLOT_SIZE

constexpr uint32_t TRX_RSEG_SLOT_SIZE = 4

constexpr

Slot size.

◆ TRX_RSEG_UNDO_SLOTS

constexpr uint32_t TRX_RSEG_UNDO_SLOTS

constexpr

Initial value:

=

8 + FLST_BASE_NODE_SIZE + FSEG_HEADER_SIZE

FSEG_HEADER_SIZE

constexpr uint32_t FSEG_HEADER_SIZE

Length of the file system header, in bytes.

Definition: fsp0types.h:94

FLST_BASE_NODE_SIZE

constexpr ulint FLST_BASE_NODE_SIZE

Definition: fut0lst.h:50

Undo log segment slots.

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ TRX_RSEG_MAX_N_TRXS

◆ TRX_RSEG_MAX_TRX_NO

◆ TRX_RSEG_N_SLOTS

◆ TRX_RSEG_SLOT_END

Function Documentation

◆ trx_rseg_adjust_rollback_segments()

◆ trx_rseg_array_create()

◆ trx_rseg_create()

◆ trx_rseg_get_n_undo_tablespaces()

◆ trx_rseg_header_create()

◆ trx_rseg_init_rollback_segments()

◆ trx_rseg_mem_create()

◆ trx_rseg_upgrade_undo_tablespaces()

◆ trx_rsegf_get()

◆ trx_rsegf_get_new()

◆ trx_rsegf_get_nth_undo()

◆ trx_rsegf_set_nth_undo()

◆ trx_rsegf_undo_find_free()

◆ trx_rsegs_init()

◆ trx_rsegs_parallel_init()

◆ trx_rsegsf_set_page_no()

Variable Documentation

◆ RSEG_ARRAY_FSEG_HEADER_OFFSET

◆ RSEG_ARRAY_HEADER

◆ RSEG_ARRAY_PAGES_OFFSET

◆ RSEG_ARRAY_RESERVED_BYTES

◆ RSEG_ARRAY_SIZE_OFFSET

◆ RSEG_ARRAY_SLOT_SIZE

◆ RSEG_ARRAY_VERSION

◆ RSEG_ARRAY_VERSION_OFFSET

◆ TRX_RSEG

◆ TRX_RSEG_FSEG_HEADER

◆ TRX_RSEG_HISTORY

◆ TRX_RSEG_HISTORY_SIZE

◆ TRX_RSEG_MAX_SIZE

◆ TRX_RSEG_SLOT_PAGE_NO

◆ TRX_RSEG_SLOT_SIZE

◆ TRX_RSEG_UNDO_SLOTS