#include "univ.i"
#include "trx0types.h"
#include "mtr0mtr.h"
#include "trx0sys.h"
#include "page0types.h"
#include "trx0xa.h"
#include "trx0undo.ic"

Include dependency graph for trx0undo.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	trx_undo_t

Macros
#define	trx_undo_free_last_page(trx, undo, mtr) trx_undo_free_last_page_func(trx,undo,mtr)
#define	trx_undo_truncate_end(trx, undo, limit) trx_undo_truncate_end_func(trx,undo,limit)
#define	TRX_UNDO_INSERT 1 /* contains undo entries for inserts */
#define	TRX_UNDO_UPDATE
#define	TRX_UNDO_ACTIVE
#define	TRX_UNDO_CACHED 2 /* cached for quick reuse */
#define	TRX_UNDO_TO_FREE 3 /* insert undo segment can be freed */
#define	TRX_UNDO_TO_PURGE
#define	TRX_UNDO_PREPARED
#define	TRX_UNDO_PAGE_HDR FSEG_PAGE_DATA
#define	TRX_UNDO_PAGE_REUSE_LIMIT (3 * UNIV_PAGE_SIZE / 4)
#define	TRX_UNDO_SEG_HDR (TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_HDR_SIZE)

#define	TRX_UNDO_PAGE_TYPE 0
#define	TRX_UNDO_PAGE_START 2
#define	TRX_UNDO_PAGE_FREE 4
#define	TRX_UNDO_PAGE_NODE 6
#define	TRX_UNDO_PAGE_HDR_SIZE (6 + FLST_NODE_SIZE)

#define	TRX_UNDO_STATE 0
#define	TRX_UNDO_LAST_LOG 2
#define	TRX_UNDO_FSEG_HEADER 4
#define	TRX_UNDO_PAGE_LIST (4 + FSEG_HEADER_SIZE)
#define	TRX_UNDO_SEG_HDR_SIZE (4 + FSEG_HEADER_SIZE + FLST_BASE_NODE_SIZE)

#define	TRX_UNDO_TRX_ID 0
#define	TRX_UNDO_TRX_NO 8
#define	TRX_UNDO_DEL_MARKS 16
#define	TRX_UNDO_LOG_START 18
#define	TRX_UNDO_XID_EXISTS 20
#define	TRX_UNDO_DICT_TRANS 21
#define	TRX_UNDO_TABLE_ID 22
#define	TRX_UNDO_NEXT_LOG 30
#define	TRX_UNDO_PREV_LOG 32
#define	TRX_UNDO_HISTORY_NODE 34
#define	TRX_UNDO_LOG_OLD_HDR_SIZE (34 + FLST_NODE_SIZE)
#define	TRX_UNDO_XA_FORMAT (TRX_UNDO_LOG_OLD_HDR_SIZE)
#define	TRX_UNDO_XA_TRID_LEN (TRX_UNDO_XA_FORMAT + 4)
#define	TRX_UNDO_XA_BQUAL_LEN (TRX_UNDO_XA_TRID_LEN + 4)
#define	TRX_UNDO_XA_XID (TRX_UNDO_XA_BQUAL_LEN + 4)
#define	TRX_UNDO_LOG_XA_HDR_SIZE (TRX_UNDO_XA_XID + XIDDATASIZE)

Functions
UNIV_INLINE roll_ptr_t	trx_undo_build_roll_ptr (ibool is_insert, ulint rseg_id, ulint page_no, ulint offset)
UNIV_INLINE void	trx_undo_decode_roll_ptr (roll_ptr_t roll_ptr, ibool is_insert, ulint rseg_id, ulint page_no, ulint offset)
UNIV_INLINE ibool	trx_undo_roll_ptr_is_insert (roll_ptr_t roll_ptr)
UNIV_INLINE bool	trx_undo_trx_id_is_insert (const byte *trx_id))
UNIV_INLINE void	trx_write_roll_ptr (byte *ptr, roll_ptr_t roll_ptr)
UNIV_INLINE roll_ptr_t	trx_read_roll_ptr (const byte *ptr)
UNIV_INLINE page_t *	trx_undo_page_get (ulint space, ulint zip_size, ulint page_no, mtr_t *mtr)
UNIV_INLINE page_t *	trx_undo_page_get_s_latched (ulint space, ulint zip_size, ulint page_no, mtr_t *mtr)
UNIV_INLINE trx_undo_rec_t *	trx_undo_page_get_prev_rec (trx_undo_rec_t *rec, ulint page_no, ulint offset)
UNIV_INLINE trx_undo_rec_t *	trx_undo_page_get_next_rec (trx_undo_rec_t *rec, ulint page_no, ulint offset)
UNIV_INLINE trx_undo_rec_t *	trx_undo_page_get_last_rec (page_t *undo_page, ulint page_no, ulint offset)
UNIV_INLINE trx_undo_rec_t *	trx_undo_page_get_first_rec (page_t *undo_page, ulint page_no, ulint offset)
UNIV_INTERN trx_undo_rec_t *	trx_undo_get_prev_rec (trx_undo_rec_t rec, ulint page_no, ulint offset, bool shared, mtr_t mtr)
UNIV_INTERN trx_undo_rec_t *	trx_undo_get_next_rec (trx_undo_rec_t rec, ulint page_no, ulint offset, mtr_t mtr)
UNIV_INTERN trx_undo_rec_t *	trx_undo_get_first_rec (ulint space, ulint zip_size, ulint page_no, ulint offset, ulint mode, mtr_t *mtr)
UNIV_INTERN buf_block_t *	trx_undo_add_page (trx_t trx, trx_undo_t undo, mtr_t *mtr))
UNIV_INTERN void	trx_undo_free_last_page_func (const trx_t trx, trx_undo_t undo, mtr_t *mtr))
UNIV_INTERN void	trx_undo_truncate_end_func (const trx_t trx, trx_undo_t undo, undo_no_t limit))
UNIV_INTERN void	trx_undo_truncate_start (trx_rseg_t *rseg, ulint space, ulint hdr_page_no, ulint hdr_offset, undo_no_t limit)
UNIV_INTERN ulint	trx_undo_lists_init (trx_rseg_t *rseg)
UNIV_INTERN dberr_t	trx_undo_assign_undo (trx_t *trx, ulint type))
UNIV_INTERN page_t *	trx_undo_set_state_at_finish (trx_undo_t undo, mtr_t mtr)
UNIV_INTERN page_t *	trx_undo_set_state_at_prepare (trx_t trx, trx_undo_t undo, mtr_t *mtr)
UNIV_INTERN void	trx_undo_update_cleanup (trx_t trx, page_t undo_page, mtr_t *mtr)
UNIV_INTERN void	trx_undo_insert_cleanup (trx_t *trx)
UNIV_INTERN void	trx_undo_free_prepared (trx_t *trx) UNIV_COLD)
UNIV_INTERN byte *	trx_undo_parse_page_init (byte ptr, byte end_ptr, page_t page, mtr_t mtr)
UNIV_INTERN byte *	trx_undo_parse_page_header (ulint type, byte ptr, byte end_ptr, page_t page, mtr_t mtr)
UNIV_INTERN byte *	trx_undo_parse_discard_latest (byte ptr, byte end_ptr, page_t page, mtr_t mtr)
UNIV_INTERN void	trx_undo_mem_free (trx_undo_t *undo)

Detailed Description

Transaction undo log

Created 3/26/1996 Heikki Tuuri

Macro Definition Documentation

#define TRX_UNDO_ACTIVE

Value:

1 /* contains an undo log of an active

transaction */

#define TRX_UNDO_DEL_MARKS 16

Defined only in an update undo log: TRUE if the transaction may have done delete markings of records, and thus purge is necessary

#define TRX_UNDO_DICT_TRANS 21

TRUE if the transaction is a table create, index create, or drop transaction: in recovery the transaction cannot be rolled back in the usual way: a 'rollback' rather means dropping the created or dropped table, if it still exists

#define TRX_UNDO_FSEG_HEADER 4

Header for the file segment which the undo log segment occupies

#define TRX_UNDO_HISTORY_NODE 34

If the log is put to the history list, the file list node is here

#define TRX_UNDO_LAST_LOG 2

Offset of the last undo log header on the segment header page, 0 if none

#define TRX_UNDO_LOG_OLD_HDR_SIZE (34 + FLST_NODE_SIZE)

Size of the undo log header without XID information

#define TRX_UNDO_LOG_START 18

Offset of the first undo log record of this log on the header page; purge may remove undo log record from the log start, and therefore this is not necessarily the same as this log header end offset

#define TRX_UNDO_LOG_XA_HDR_SIZE (TRX_UNDO_XA_XID + XIDDATASIZE)

Total size of the undo log header with the XA XID

#define TRX_UNDO_NEXT_LOG 30

Offset of the next undo log header on this page, 0 if none

#define TRX_UNDO_PAGE_FREE 4

On each page of the undo log this field contains the byte offset of the first free byte on the page

#define TRX_UNDO_PAGE_HDR FSEG_PAGE_DATA

The offset of the undo log page header on pages of the undo log

#define TRX_UNDO_PAGE_HDR_SIZE (6 + FLST_NODE_SIZE)

Size of the transaction undo log page header, in bytes

#define TRX_UNDO_PAGE_LIST (4 + FSEG_HEADER_SIZE)

Base node for the list of pages in the undo log segment; defined only on the undo log segment's first page

#define TRX_UNDO_PAGE_NODE 6

The file list node in the chain of undo log pages

#define TRX_UNDO_PAGE_REUSE_LIMIT (3 * UNIV_PAGE_SIZE / 4)

An update undo segment with just one page can be reused if it has

at most this many bytes used; we must leave space at least for one new undo log header on the page

#define TRX_UNDO_PAGE_START 2

Byte offset where the undo log records for the LATEST transaction start on this page (remember that in an update undo log, the first page can contain several undo logs)

#define TRX_UNDO_PAGE_TYPE 0

Transaction undo log page header offsets TRX_UNDO_INSERT or TRX_UNDO_UPDATE

#define TRX_UNDO_PREPARED

Value:

5 /* contains an undo log of an

prepared transaction */

#define TRX_UNDO_PREV_LOG 32

Offset of the previous undo log header on this page, 0 if none

#define TRX_UNDO_SEG_HDR (TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_HDR_SIZE)

The offset of the undo log segment header on the first page of the undo

log segment

#define TRX_UNDO_SEG_HDR_SIZE (4 + FSEG_HEADER_SIZE + FLST_BASE_NODE_SIZE)

Size of the undo log segment header

#define TRX_UNDO_STATE 0

Undo log segment header TRX_UNDO_ACTIVE, ...

#define TRX_UNDO_TABLE_ID 22

Id of the table if the preceding field is TRUE

#define TRX_UNDO_TO_PURGE

Value:

4       /* update undo segment will not be
                                        reused: it can be freed in purge when
                                        all undo data in it is removed */

#define TRX_UNDO_TRX_ID 0

The undo log header. There can be several undo log headers on the first

page of an update undo log segment. Transaction id

#define TRX_UNDO_TRX_NO 8

Transaction number of the transaction; defined only if the log is in a history list

#define TRX_UNDO_UPDATE

Value:

2       /* contains undo entries for updates
                                        and delete markings: in short,
                                        modifys (the name 'UPDATE' is a
                                        historical relic) */

#define TRX_UNDO_XA_BQUAL_LEN (TRX_UNDO_XA_TRID_LEN + 4)

xid_t::bqual_length

#define TRX_UNDO_XA_FORMAT (TRX_UNDO_LOG_OLD_HDR_SIZE)

X/Open XA Transaction Identification (XID) xid_t::formatID

#define TRX_UNDO_XA_TRID_LEN (TRX_UNDO_XA_FORMAT + 4)

xid_t::gtrid_length

#define TRX_UNDO_XA_XID (TRX_UNDO_XA_BQUAL_LEN + 4)

Distributed transaction identifier data

#define TRX_UNDO_XID_EXISTS 20

TRUE if undo log header includes X/Open XA transaction identification XID

Function Documentation

UNIV_INLINE roll_ptr_t trx_read_roll_ptr ( const byte * ptr )

Reads a roll ptr from an index page. In case that the roll ptr size changes in some future version, this function should be used instead of mach_read_...

Returns: roll ptr in: pointer to memory from where to read

Reads a roll ptr from an index page. In case that the roll ptr size changes in some future version, this function should be used instead of mach_read_...

Returns: roll ptr

Parameters

ptr	in: pointer to memory from where to read

UNIV_INTERN buf_block_t* trx_undo_add_page	(	trx_t *	trx,
		trx_undo_t *	undo,
		mtr_t *	mtr
	)

Tries to add a page to the undo log segment where the undo log is placed.

Returns: X-latched block if success, else NULL

Parameters

trx	in: transaction
undo	in: undo log memory object
mtr	in: mtr which does not have a latch to any undo log page; the caller must have reserved the rollback segment mutex

UNIV_INTERN dberr_t trx_undo_assign_undo	(	trx_t *	trx,
		ulint	type
	)

Assigns an undo log for a transaction. A new undo log is created or a cached undo log reused.

Returns: DB_SUCCESS if undo log assign successful, possible error codes are: DB_TOO_MANY_CONCURRENT_TRXS DB_OUT_OF_FILE_SPACE DB_READ_ONLY DB_OUT_OF_MEMORY

Parameters

trx	in: transaction
type	in: TRX_UNDO_INSERT or TRX_UNDO_UPDATE

UNIV_INLINE roll_ptr_t trx_undo_build_roll_ptr	(	ibool	is_insert,
		ulint	rseg_id,
		ulint	page_no,
		ulint	offset
	)

Builds a roll pointer.

Returns: roll pointer in: offset of the undo entry within page

Builds a roll pointer.

Returns: roll pointer

Parameters

is_insert	in: TRUE if insert undo log
rseg_id	in: rollback segment id
page_no	in: page number
offset	in: offset of the undo entry within page

UNIV_INLINE void trx_undo_decode_roll_ptr	(	roll_ptr_t	roll_ptr,
		ibool *	is_insert,
		ulint *	rseg_id,
		ulint *	page_no,
		ulint *	offset
	)

Decodes a roll pointer. out: offset of the undo entry within page

Decodes a roll pointer.

Parameters

roll_ptr	in: roll pointer
is_insert	out: TRUE if insert undo log
rseg_id	out: rollback segment id
page_no	out: page number
offset	out: offset of the undo entry within page

UNIV_INTERN void trx_undo_free_last_page_func	(	const trx_t *	trx,
		trx_undo_t *	undo,
		mtr_t *	mtr
	)

Frees the last undo log page. The caller must hold the rollback segment mutex.

Parameters

trx	in: transaction
undo	in/out: undo log memory copy
mtr	in/out: mini-transaction which does not have a latch to any undo log page or which has allocated the undo log page

UNIV_INTERN void trx_undo_free_prepared ( trx_t * trx )

At shutdown, frees the undo logs of a PREPARED transaction.

Parameters

trx	in/out: PREPARED transaction

UNIV_INTERN trx_undo_rec_t* trx_undo_get_first_rec	(	ulint	space,
		ulint	zip_size,
		ulint	page_no,
		ulint	offset,
		ulint	mode,
		mtr_t *	mtr
	)

Gets the first record in an undo log.

Returns: undo log record, the page latched, NULL if none in: mtr

Parameters

space	in: undo log header space
zip_size	in: compressed page size in bytes or 0 for uncompressed pages
page_no	in: undo log header page number
offset	in: undo log header offset on page
mode	in: latching mode: RW_S_LATCH or RW_X_LATCH

UNIV_INTERN trx_undo_rec_t* trx_undo_get_next_rec	(	trx_undo_rec_t *	rec,
		ulint	page_no,
		ulint	offset,
		mtr_t *	mtr
	)

Gets the next record in an undo log.

Returns: undo log record, the page s-latched, NULL if none in: mtr

Parameters

rec	in: undo record
page_no	in: undo log header page number
offset	in: undo log header offset on page

UNIV_INTERN trx_undo_rec_t* trx_undo_get_prev_rec	(	trx_undo_rec_t *	rec,
		ulint	page_no,
		ulint	offset,
		bool	shared,
		mtr_t *	mtr
	)

Gets the previous record in an undo log.

Returns: undo log record, the page s-latched, NULL if none in: mtr

Parameters

rec	in: undo record
page_no	in: undo log header page number
offset	in: undo log header offset on page
shared	in: true=S-latch, false=X-latch

UNIV_INTERN void trx_undo_insert_cleanup ( trx_t * trx )

Frees or caches an insert undo log after a transaction commit or rollback. Knowledge of inserts is not needed after a commit or rollback, therefore the data can be discarded. in: transaction handle

UNIV_INTERN ulint trx_undo_lists_init ( trx_rseg_t * rseg )

Initializes the undo log lists for a rollback segment memory copy. This function is only called when the database is started or a new rollback segment created.

Returns: the combined size of undo log segments in pages in: rollback segment memory object

UNIV_INLINE page_t* trx_undo_page_get	(	ulint	space,
		ulint	zip_size,
		ulint	page_no,
		mtr_t *	mtr
	)

Gets an undo log page and x-latches it.

Returns: pointer to page x-latched in: mtr

Gets an undo log page and x-latches it.

Returns: pointer to page x-latched

Parameters

space	in: space where placed
zip_size	in: compressed page size in bytes or 0 for uncompressed pages
page_no	in: page number
mtr	in: mtr

UNIV_INLINE trx_undo_rec_t* trx_undo_page_get_first_rec	(	page_t *	undo_page,
		ulint	page_no,
		ulint	offset
	)

Returns the first undo record on the page in the specified undo log, or NULL if none exists.

Returns: pointer to record, NULL if none in: undo log header offset on page

Returns the first undo record on the page in the specified undo log, or NULL if none exists.

Returns: pointer to record, NULL if none

Parameters

undo_page	in: undo log page
page_no	in: undo log header page number
offset	in: undo log header offset on page

UNIV_INLINE trx_undo_rec_t* trx_undo_page_get_last_rec	(	page_t *	undo_page,
		ulint	page_no,
		ulint	offset
	)

Returns the last undo record on the page in the specified undo log, or NULL if none exists.

Returns: pointer to record, NULL if none in: undo log header offset on page

Returns the last undo record on the page in the specified undo log, or NULL if none exists.

Returns: pointer to record, NULL if none

Parameters

undo_page	in: undo log page
page_no	in: undo log header page number
offset	in: undo log header offset on page

UNIV_INLINE trx_undo_rec_t* trx_undo_page_get_next_rec	(	trx_undo_rec_t *	rec,
		ulint	page_no,
		ulint	offset
	)

Returns the next undo log record on the page in the specified log, or NULL if none exists.

Returns: pointer to record, NULL if none in: undo log header offset on page

Returns the next undo log record on the page in the specified log, or NULL if none exists.

Returns: pointer to record, NULL if none

Parameters

rec	in: undo log record
page_no	in: undo log header page number
offset	in: undo log header offset on page

UNIV_INLINE trx_undo_rec_t* trx_undo_page_get_prev_rec	(	trx_undo_rec_t *	rec,
		ulint	page_no,
		ulint	offset
	)

Returns the previous undo record on the page in the specified log, or NULL if none exists.

Returns: pointer to record, NULL if none in: undo log header offset on page

Returns the previous undo record on the page in the specified log, or NULL if none exists.

Returns: pointer to record, NULL if none

Parameters

rec	in: undo log record
page_no	in: undo log header page number
offset	in: undo log header offset on page

UNIV_INLINE page_t* trx_undo_page_get_s_latched	(	ulint	space,
		ulint	zip_size,
		ulint	page_no,
		mtr_t *	mtr
	)

Gets an undo log page and s-latches it.

Returns: pointer to page s-latched in: mtr

Gets an undo log page and s-latches it.

Returns: pointer to page s-latched

Parameters

space	in: space where placed
zip_size	in: compressed page size in bytes or 0 for uncompressed pages
page_no	in: page number
mtr	in: mtr

UNIV_INTERN byte* trx_undo_parse_discard_latest	(	byte *	ptr,
		byte *	end_ptr,
		page_t *	page,
		mtr_t *	mtr
	)

Parses the redo log entry of an undo log page header discard.

Returns: end of log record or NULL in: mtr or NULL

Parameters

ptr	in: buffer
end_ptr	in: buffer end
page	in: page or NULL

UNIV_INTERN byte* trx_undo_parse_page_header	(	ulint	type,
		byte *	ptr,
		byte *	end_ptr,
		page_t *	page,
		mtr_t *	mtr
	)

Parses the redo log entry of an undo log page header create or reuse.

Returns: end of log record or NULL in: mtr or NULL

Parameters

type	in: MLOG_UNDO_HDR_CREATE or MLOG_UNDO_HDR_REUSE
ptr	in: buffer
end_ptr	in: buffer end
page	in: page or NULL

UNIV_INTERN byte* trx_undo_parse_page_init	(	byte *	ptr,
		byte *	end_ptr,
		page_t *	page,
		mtr_t *	mtr
	)

Parses the redo log entry of an undo log page initialization.

Returns: end of log record or NULL in: mtr or NULL

Parameters

ptr	in: buffer
end_ptr	in: buffer end
page	in: page or NULL

UNIV_INLINE ibool trx_undo_roll_ptr_is_insert ( roll_ptr_t roll_ptr )

Returns TRUE if the roll pointer is of the insert type.

Returns: TRUE if insert undo log in: roll pointer

Returns TRUE if the roll pointer is of the insert type.

Returns: TRUE if insert undo log

Parameters

roll_ptr in: roll pointer

UNIV_INTERN page_t* trx_undo_set_state_at_finish	(	trx_undo_t *	undo,
		mtr_t *	mtr
	)

Sets the state of the undo log segment at a transaction finish.

Returns: undo log segment header page, x-latched in: mtr

Parameters

undo	in: undo log memory copy

UNIV_INTERN page_t* trx_undo_set_state_at_prepare	(	trx_t *	trx,
		trx_undo_t *	undo,
		mtr_t *	mtr
	)

Sets the state of the undo log segment at a transaction prepare.

Returns: undo log segment header page, x-latched in: mtr

Parameters

trx	in: transaction
undo	in: undo log memory copy

UNIV_INTERN void trx_undo_truncate_end_func	(	const trx_t *	trx,
		trx_undo_t *	undo,
		undo_no_t	limit
	)

Truncates an undo log from the end. This function is used during a rollback to free space from an undo log.

Parameters

trx	in: transaction whose undo log it is
undo	in/out: undo log
limit	in: all undo records with undo number >= this value should be truncated

UNIV_INTERN void trx_undo_truncate_start	(	trx_rseg_t *	rseg,
		ulint	space,
		ulint	hdr_page_no,
		ulint	hdr_offset,
		undo_no_t	limit
	)

Truncates an undo log from the start. This function is used during a purge operation. in: all undo pages with undo numbers < this value should be truncated; NOTE that the function only frees whole pages; the header page is not freed, but emptied, if all the records there are < limit

Parameters

rseg	in: rollback segment
space	in: space id of the log
hdr_page_no	in: header page number
hdr_offset	in: header offset on the page

UNIV_INLINE bool trx_undo_trx_id_is_insert ( const byte * trx_id )

Returns true if the record is of the insert type.

Returns: true if the record was freshly inserted (not updated).

Parameters

trx_id in: DB_TRX_ID, followed by DB_ROLL_PTR

UNIV_INTERN void trx_undo_update_cleanup	(	trx_t *	trx,
		page_t *	undo_page,
		mtr_t *	mtr
	)

Adds the update undo log header as the first in the history list, and frees the memory object, or puts it to the list of cached update undo log segments. in: mtr

Parameters

trx	in: trx owning the update undo log
undo_page	in: update undo log header page, x-latched

UNIV_INLINE void trx_write_roll_ptr	(	byte *	ptr,
		roll_ptr_t	roll_ptr
	)

Writes a roll ptr to an index page. In case that the size changes in some future version, this function should be used instead of mach_write_... in: roll ptr

Writes a roll ptr to an index page. In case that the size changes in some future version, this function should be used instead of mach_write_...

Parameters

ptr	in: pointer to memory where written
roll_ptr	in: roll ptr

Data Structures

Macros

Functions

Detailed Description

Macro Definition Documentation

Function Documentation