Transaction undo log record. More...

#include "univ.i"
#include "data0data.h"
#include "dict0types.h"
#include "lob0undo.h"
#include "mtr0mtr.h"
#include "page0types.h"
#include "rem0types.h"
#include "row0log.h"
#include "row0types.h"
#include "trx0types.h"
#include "que0types.h"
#include "trx0rec.ic"

Classes
struct	type_cmpl_t
	The type and compilation info flag in the undo record for update. More...

Functions
static trx_undo_rec_t *	trx_undo_rec_copy (const page_t undo_page, uint32_t undo_offset, mem_heap_t heap)
	Copies the undo record to the heap. More...

static ulint	trx_undo_rec_get_type (const trx_undo_rec_t *undo_rec)
	Reads the undo log record type. More...

static ulint	trx_undo_rec_get_cmpl_info (const trx_undo_rec_t *undo_rec)
	Reads from an undo log record the record compiler info. More...

static bool	trx_undo_rec_get_extern_storage (const trx_undo_rec_t *undo_rec)
	Returns true if an undo log record contains an extern storage field. More...

static undo_no_t	trx_undo_rec_get_undo_no (const trx_undo_rec_t *undo_rec)
	Reads the undo log record number. More...

table_id_t	trx_undo_rec_get_table_id (const trx_undo_rec_t *undo_rec)
	Reads from an undo log record the table ID. More...

byte *	trx_undo_rec_get_row_ref (byte ptr, dict_index_t index, dtuple_t *ref, mem_heap_t heap)
	Builds a row reference from an undo log record. More...

byte *	trx_undo_update_rec_get_sys_cols (const byte ptr, trx_id_t trx_id, roll_ptr_t roll_ptr, ulint info_bits)
	Reads from an undo log update record the system field values of the old version. More...

byte *	trx_undo_update_rec_get_update (const byte ptr, const dict_index_t index, ulint type, trx_id_t trx_id, roll_ptr_t roll_ptr, ulint info_bits, mem_heap_t heap, upd_t upd, lob::undo_vers_t lob_undo, type_cmpl_t &type_cmpl)
	Builds an update vector based on a remaining part of an undo log record. More...

byte *	trx_undo_rec_get_partial_row (const byte ptr, dict_index_t index, dtuple_t *row, bool ignore_prefix, mem_heap_t heap)
	Builds a partial row from an update undo log record, for purge. More...

dberr_t	trx_undo_report_row_operation (ulint flags, ulint op_type, que_thr_t thr, dict_index_t index, const dtuple_t clust_entry, const upd_t update, ulint cmpl_info, const rec_t rec, const ulint offsets, roll_ptr_t *roll_ptr)
	Writes information to an undo log about an insert, update, or a delete marking of a clustered index record. More...

bool	trx_undo_prev_version_build (const rec_t index_rec, mtr_t index_mtr, const rec_t rec, const dict_index_t index, ulint offsets, mem_heap_t heap, rec_t *old_vers, mem_heap_t v_heap, const dtuple_t *vrow, ulint v_status, lob::undo_vers_t lob_undo)
	Build a previous version of a clustered index record. More...

byte *	trx_undo_parse_add_undo_rec (byte ptr, byte end_ptr, page_t *page)
	Parses a redo log record of adding an undo log record. More...

byte *	trx_undo_parse_erase_page_end (byte ptr, byte end_ptr, page_t page, mtr_t mtr)
	Parses a redo log record of erasing of an undo page end. More...

byte *	trx_undo_rec_get_col_val (const byte ptr, const byte field, ulint len, ulint *orig_len)
	Read from an undo log record a non-virtual column value. More...

void	trx_undo_read_v_cols (const dict_table_t table, const byte ptr, const dtuple_t row, bool in_purge, bool online, const ulint col_map, mem_heap_t *heap)
	Read virtual column value from undo log. More...

const byte *	trx_undo_read_v_idx (const dict_table_t table, const byte ptr, bool first_v_col, bool is_undo_log, ulint field_no)
	Read virtual column index from undo log or online log if the log contains such info, and in the undo log case, verify the column is still indexed, and output its position. More...

byte *	trx_undo_rec_get_pars (trx_undo_rec_t undo_rec, ulint type, ulint cmpl_info, bool updated_extern, undo_no_t undo_no, table_id_t table_id, type_cmpl_t &type_cmpl)
	Reads from an undo log record the general parameters. More...

size_t	trx_undo_max_free_space ()
	Get the max free space of undo log by assuming it's a fresh new page and the free space doesn't count for the undo log header too. More...

bool	trx_undo_rec_is_multi_value (const byte *undo_rec)
	Decide if the following undo log record is a multi-value virtual column. More...

const byte *	trx_undo_rec_get_multi_value (const byte ptr, dfield_t field, mem_heap_t *heap)
	Read from an undo log record of a multi-value virtual column. More...

Variables
constexpr uint32_t	TRX_UNDO_PREV_IN_PURGE = 0x1
	status bit used for trx_undo_prev_version_build() More...

constexpr uint32_t	TRX_UNDO_GET_OLD_V_VALUE = 0x2
	This tells trx_undo_prev_version_build() to fetch the old value in the undo log (which is the after image for an update) More...

constexpr uint32_t	TRX_UNDO_INSERT_REC = 11
	fresh insert into clustered index More...

constexpr uint32_t	TRX_UNDO_UPD_EXIST_REC = 12
	update of a non-delete-marked record More...

constexpr uint32_t	TRX_UNDO_UPD_DEL_REC = 13
	update of a delete marked record to a not delete marked record; also the fields of the record can change More...

constexpr uint32_t	TRX_UNDO_DEL_MARK_REC = 14

constexpr uint32_t	TRX_UNDO_CMPL_INFO_MULT = 16
	compilation info is multiplied by this and ORed to the type above More...

constexpr uint32_t	TRX_UNDO_MODIFY_BLOB = 64
	If this bit is set in type_cmpl, then the undo log record has support for partial update of BLOBs. More...

constexpr uint32_t	TRX_UNDO_UPD_EXTERN = 128

constexpr uint32_t	TRX_UNDO_INSERT_OP = 1
	Operation type flags used in trx_undo_report_row_operation. More...

constexpr uint32_t	TRX_UNDO_MODIFY_OP = 2

Detailed Description

Transaction undo log record.

Created 3/26/1996 Heikki Tuuri

Function Documentation

◆ trx_undo_max_free_space()

size_t trx_undo_max_free_space ( )

Get the max free space of undo log by assuming it's a fresh new page and the free space doesn't count for the undo log header too.

◆ trx_undo_parse_add_undo_rec()

byte * trx_undo_parse_add_undo_rec	(	byte *	ptr,
		byte *	end_ptr,
		page_t *	page
	)

Parses a redo log record of adding an undo log record.

Returns: end of log record or NULL in: page or NULL; end of log record or NULL

Parameters

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

◆ trx_undo_parse_erase_page_end()

byte * trx_undo_parse_erase_page_end	(	byte *	ptr,
		byte *	end_ptr,
		page_t *	page,
		mtr_t *	mtr
	)

Parses a redo log record of erasing of an undo page end.

Parameters

[in,out]	ptr	Buffer.
[in,out]	end_ptr	Buffer end.
[in,out]	page	Page or nullptr.
[in,out]	mtr	MTR or nullptr.

Returns: end of log record or nullptr

◆ trx_undo_prev_version_build()

bool trx_undo_prev_version_build	(	const rec_t *	index_rec,
		mtr_t *	index_mtr,
		const rec_t *	rec,
		const dict_index_t *	index,
		ulint *	offsets,
		mem_heap_t *	heap,
		rec_t **	old_vers,
		mem_heap_t *	v_heap,
		const dtuple_t **	vrow,
		ulint	v_status,
		lob::undo_vers_t *	lob_undo
	)

Build a previous version of a clustered index record.

The caller must hold a latch on the index page of the clustered index record. If the vrow passed to this function is not null, then this function will store information about virtual columns from the requested version in vrow, unless the change did not affect any secondary index nor ordering field of clustered index (the change has UPD_NODE_NO_ORD_CHANGE flag) in which case the requested information can not be reconstructed from undo log, and the caller may assume that the (virtual) columns of secondary index have the same values they have in the more recent version (the one rec comes from). Equivalently, if the vrow is not returned, it is either because it was not requested, or not available due to UPD_NODE_NO_ORD_CHANGE. Obviously vrow is also not set in case rec is the oldest version in history, in which case we also set old_vers to NULL.

Parameters

[in]	index_rec	clustered index record in the index tree
[in]	index_mtr	mtr which contains the latch to index_rec page and purge_view
[in]	rec	version of a clustered index record
[in]	index	clustered index
[in,out]	offsets	rec_get_offsets(rec, index)
[in]	heap	memory heap from which the memory needed is allocated
[out]	old_vers	previous version, or NULL if rec is the first inserted version, or if history data has been deleted
[in]	v_heap	memory heap used to create vrow dtuple if it is not yet created. This heap diffs from "heap" above in that it could be prebuilt->old_vers_heap for selection
[out]	vrow	virtual column info, if any
[in]	v_status	status determine if it is going into this function by purge thread or not. And if we read "after image" of undo log has been rebuilt
[in]	lob_undo	LOB undo information.

Return values

true	if previous version was built, or if it was an insert or the table has been rebuilt
false	if the previous version is earlier than purge_view, or being purged, which means that it may have been removed

◆ trx_undo_read_v_cols()

void trx_undo_read_v_cols	(	const dict_table_t *	table,
		const byte *	ptr,
		const dtuple_t *	row,
		bool	in_purge,
		bool	online,
		const ulint *	col_map,
		mem_heap_t *	heap
	)

Read virtual column value from undo log.

Parameters

[in]	table	the table
[in]	ptr	undo log pointer
[in,out]	row	the dtuple to fill
[in]	in_purge	called by purge thread
[in]	online	true if this is from online DDL log
[in]	col_map	online rebuild column map
[in,out]	heap	memory heap to keep value when necessary

◆ trx_undo_read_v_idx()

const byte * trx_undo_read_v_idx	(	const dict_table_t *	table,
		const byte *	ptr,
		bool	first_v_col,
		bool *	is_undo_log,
		ulint *	field_no
	)

Read virtual column index from undo log or online log if the log contains such info, and in the undo log case, verify the column is still indexed, and output its position.

Parameters

[in]	table	the table
[in]	ptr	undo log pointer
[in]	first_v_col	if this is the first virtual column, which has the version marker
[in,out]	is_undo_log	this function is used to parse both undo log, and online log for virtual columns. So check to see if this is undo log. When first_v_col is true, is_undo_log is output, when first_v_col is false, is_undo_log is input
[in,out]	field_no	the column number

Returns: remaining part of undo log record after reading these values

◆ trx_undo_rec_copy()

static trx_undo_rec_t * trx_undo_rec_copy	(	const page_t *	undo_page,
		uint32_t	undo_offset,
		mem_heap_t *	heap
	)

inlinestatic

Copies the undo record to the heap.

Parameters

[in]	undo_page	Undo Page
[in]	undo_offset	offset of the undo record in the page
[in]	heap	heap where copied

Returns: copy of undo log record

◆ trx_undo_rec_get_cmpl_info()

static ulint trx_undo_rec_get_cmpl_info ( const trx_undo_rec_t * undo_rec )

inlinestatic

Reads from an undo log record the record compiler info.

Returns: compiler info in: undo log record

◆ trx_undo_rec_get_col_val()

byte * trx_undo_rec_get_col_val	(	const byte *	ptr,
		const byte **	field,
		ulint *	len,
		ulint *	orig_len
	)

Read from an undo log record a non-virtual column value.

Parameters

[in,out]	ptr	pointer to remaining part of the undo record
[in,out]	field	stored field
[in,out]	len	length of the field, or UNIV_SQL_NULL
[in,out]	orig_len	original length of the locally stored part of an externally stored column, or 0

Returns: remaining part of undo log record after reading these values

◆ trx_undo_rec_get_extern_storage()

static bool trx_undo_rec_get_extern_storage ( const trx_undo_rec_t * undo_rec )

inlinestatic

Returns true if an undo log record contains an extern storage field.

Returns: true if extern in: undo log record

◆ trx_undo_rec_get_multi_value()

const byte * trx_undo_rec_get_multi_value	(	const byte *	ptr,
		dfield_t *	field,
		mem_heap_t *	heap
	)

Read from an undo log record of a multi-value virtual column.

Parameters

[in]	ptr	pointer to remaining part of the undo record
[in,out]	field	stored field, nullptr if the col is no longer indexed or existing, in the latter case, this function will only skip the log
[in,out]	heap	memory heap

Returns: remaining part of undo log record after reading these values

◆ trx_undo_rec_get_pars()

byte * trx_undo_rec_get_pars	(	trx_undo_rec_t *	undo_rec,
		ulint *	type,
		ulint *	cmpl_info,
		bool *	updated_extern,
		undo_no_t *	undo_no,
		table_id_t *	table_id,
		type_cmpl_t &	type_cmpl
	)

Reads from an undo log record the general parameters.

Returns: remaining part of undo log record after reading these values out: type compilation info.; remaining part of undo log record after reading these values

Parameters

undo_rec	in: undo log record
type	out: undo record type: TRX_UNDO_INSERT_REC, ...
cmpl_info	out: compiler info, relevant only for update type records
updated_extern	out: true if we updated an externally stored fild
undo_no	out: undo log record number
table_id	out: table id
type_cmpl	out: type compilation info

◆ trx_undo_rec_get_partial_row()

byte * trx_undo_rec_get_partial_row	(	const byte *	ptr,
		dict_index_t *	index,
		dtuple_t **	row,
		bool	ignore_prefix,
		mem_heap_t *	heap
	)

Builds a partial row from an update undo log record, for purge.

It contains the columns which occur as ordering in any index of the table. Any missing columns are indicated by col->mtype == DATA_MISSING.

Returns: pointer to remaining part of undo record in: memory heap from which the memory needed is allocated

It contains the columns which occur as ordering in any index of the table. Any missing columns are indicated by col->mtype == DATA_MISSING.

Returns: pointer to remaining part of undo record

Parameters

ptr	in: remaining part in update undo log record of a suitable type, at the start of the stored index columns; NOTE that this copy of the undo log record must be preserved as long as the partial row is used, as we do NOT copy the data in the record!
index	in: clustered index
row	out, own: partial row
ignore_prefix	in: flag to indicate if we expect blob prefixes in undo. Used only in the assertion.
heap	in: memory heap from which the memory needed is allocated

◆ trx_undo_rec_get_row_ref()

byte * trx_undo_rec_get_row_ref	(	byte *	ptr,
		dict_index_t *	index,
		dtuple_t **	ref,
		mem_heap_t *	heap
	)

Builds a row reference from an undo log record.

Returns: pointer to remaining part of undo record in: memory heap from which the memory needed is allocated; pointer to remaining part of undo record

Parameters

ptr	in: remaining part of a copy of an undo log record, at the start of the row reference; NOTE that this copy of the undo log record must be preserved as long as the row reference is used, as we do NOT copy the data in the record!
index	in: clustered index
ref	out, own: row reference
heap	in: memory heap from which the memory needed is allocated

◆ trx_undo_rec_get_table_id()

table_id_t trx_undo_rec_get_table_id ( const trx_undo_rec_t * undo_rec )

Reads from an undo log record the table ID.

Parameters

[in] undo_rec Undo log record

Returns: the table ID

◆ trx_undo_rec_get_type()

static ulint trx_undo_rec_get_type ( const trx_undo_rec_t * undo_rec )

inlinestatic

Reads the undo log record type.

Returns: record type in: undo log record

◆ trx_undo_rec_get_undo_no()

static undo_no_t trx_undo_rec_get_undo_no ( const trx_undo_rec_t * undo_rec )

inlinestatic

Reads the undo log record number.

Returns: undo no in: undo log record

◆ trx_undo_rec_is_multi_value()

bool trx_undo_rec_is_multi_value ( const byte * undo_rec )

Decide if the following undo log record is a multi-value virtual column.

Parameters

[in] undo_rec undo log record

Returns: true if this is a multi-value virtual column log, otherwise false

◆ trx_undo_report_row_operation()

dberr_t trx_undo_report_row_operation	(	ulint	flags,
		ulint	op_type,
		que_thr_t *	thr,
		dict_index_t *	index,
		const dtuple_t *	clust_entry,
		const upd_t *	update,
		ulint	cmpl_info,
		const rec_t *	rec,
		const ulint *	offsets,
		roll_ptr_t *	roll_ptr
	)

Writes information to an undo log about an insert, update, or a delete marking of a clustered index record.

This information is used in a rollback of the transaction and in consistent reads that must look to the history of this transaction.

Returns: DB_SUCCESS or error code out: rollback pointer to the inserted undo log record, 0 if BTR_NO_UNDO_LOG flag was specified

This information is used in a rollback of the transaction and in consistent reads that must look to the history of this transaction.

Returns: DB_SUCCESS or error code

Parameters

flags	in: if BTR_NO_UNDO_LOG_FLAG bit is set, does nothing
op_type	in: TRX_UNDO_INSERT_OP or TRX_UNDO_MODIFY_OP
thr	in: query thread
index	in: clustered index
clust_entry	in: in the case of an insert, index entry to insert into the clustered index, otherwise NULL
update	in: in the case of an update, the update vector, otherwise NULL
cmpl_info	in: compiler info on secondary index updates
rec	in: in case of an update or delete marking, the record in the clustered index, otherwise NULL
offsets	in: rec_get_offsets(rec)
roll_ptr	out: rollback pointer to the inserted undo log record, 0 if BTR_NO_UNDO_LOG flag was specified

◆ trx_undo_update_rec_get_sys_cols()

byte * trx_undo_update_rec_get_sys_cols	(	const byte *	ptr,
		trx_id_t *	trx_id,
		roll_ptr_t *	roll_ptr,
		ulint *	info_bits
	)

Reads from an undo log update record the system field values of the old version.

Returns: remaining part of undo log record after reading these values out: info bits state; remaining part of undo log record after reading these values

Parameters

ptr	in: remaining part of undo log record after reading general parameters
trx_id	out: trx id
roll_ptr	out: roll ptr
info_bits	out: info bits state

◆ trx_undo_update_rec_get_update()

byte * trx_undo_update_rec_get_update	(	const byte *	ptr,
		const dict_index_t *	index,
		ulint	type,
		trx_id_t	trx_id,
		roll_ptr_t	roll_ptr,
		ulint	info_bits,
		mem_heap_t *	heap,
		upd_t **	upd,
		lob::undo_vers_t *	lob_undo,
		type_cmpl_t &	type_cmpl
	)

Builds an update vector based on a remaining part of an undo log record.

Parameters

[in]	ptr	Remaining part in update undo log record, after reading the row reference. NOTE that this copy of the undo log record must be preserved as long as the update vector is used, as we do NOT copy the data in the record!
[in]	index	Clustered index.
[in]	type	TRX_UNDO_UPD_EXIST_REC, TRX_UNDO_UPD_DEL_REC, or TRX_UNDO_DEL_MARK_REC; in the last case, only trx id and roll ptr fields are added to the update vector.
[in]	trx_id	Transaction id from this undo record.
[in]	roll_ptr	Roll pointer from this undo record.
[in]	info_bits	Info bits from this undo record.
[in]	heap	Memory heap from which the memory needed is allocated.
[out]	upd	Update vector.
[out]	lob_undo	LOB undo information.
[out]	type_cmpl	Type compilation info.

Returns: remaining part of the record, NULL if an error detected, which means that the record is corrupted.

Variable Documentation

◆ TRX_UNDO_CMPL_INFO_MULT

constexpr uint32_t TRX_UNDO_CMPL_INFO_MULT = 16

constexpr

compilation info is multiplied by this and ORed to the type above

◆ TRX_UNDO_DEL_MARK_REC

constexpr uint32_t TRX_UNDO_DEL_MARK_REC = 14

constexpr

◆ TRX_UNDO_GET_OLD_V_VALUE

constexpr uint32_t TRX_UNDO_GET_OLD_V_VALUE = 0x2

constexpr

This tells trx_undo_prev_version_build() to fetch the old value in the undo log (which is the after image for an update)

◆ TRX_UNDO_INSERT_OP

constexpr uint32_t TRX_UNDO_INSERT_OP = 1

constexpr

Operation type flags used in trx_undo_report_row_operation.

◆ TRX_UNDO_INSERT_REC

constexpr uint32_t TRX_UNDO_INSERT_REC = 11

constexpr

fresh insert into clustered index

◆ TRX_UNDO_MODIFY_BLOB

constexpr uint32_t TRX_UNDO_MODIFY_BLOB = 64

constexpr

If this bit is set in type_cmpl, then the undo log record has support for partial update of BLOBs.

Also to make the undo log format extensible, introducing a new flag next to the type_cmpl flag.

◆ TRX_UNDO_MODIFY_OP

constexpr uint32_t TRX_UNDO_MODIFY_OP = 2

constexpr

◆ TRX_UNDO_PREV_IN_PURGE

constexpr uint32_t TRX_UNDO_PREV_IN_PURGE = 0x1

constexpr

status bit used for trx_undo_prev_version_build()

TRX_UNDO_PREV_IN_PURGE tells trx_undo_prev_version_build() that it is being called purge view and we would like to get the purge record even it is in the purge view (in normal case, it will return without fetching the purge record

◆ TRX_UNDO_UPD_DEL_REC

constexpr uint32_t TRX_UNDO_UPD_DEL_REC = 13

constexpr

update of a delete marked record to a not delete marked record; also the fields of the record can change

◆ TRX_UNDO_UPD_EXIST_REC

constexpr uint32_t TRX_UNDO_UPD_EXIST_REC = 12

constexpr

update of a non-delete-marked record

◆ TRX_UNDO_UPD_EXTERN

constexpr uint32_t TRX_UNDO_UPD_EXTERN = 128

constexpr

Classes

Functions

Variables

Detailed Description

Function Documentation

◆ trx_undo_max_free_space()

◆ trx_undo_parse_add_undo_rec()

◆ trx_undo_parse_erase_page_end()

◆ trx_undo_prev_version_build()

◆ trx_undo_read_v_cols()

◆ trx_undo_read_v_idx()

◆ trx_undo_rec_copy()

◆ trx_undo_rec_get_cmpl_info()

◆ trx_undo_rec_get_col_val()

◆ trx_undo_rec_get_extern_storage()

◆ trx_undo_rec_get_multi_value()

◆ trx_undo_rec_get_pars()

◆ trx_undo_rec_get_partial_row()

◆ trx_undo_rec_get_row_ref()

◆ trx_undo_rec_get_table_id()

◆ trx_undo_rec_get_type()

◆ trx_undo_rec_get_undo_no()

◆ trx_undo_rec_is_multi_value()

◆ trx_undo_report_row_operation()

◆ trx_undo_update_rec_get_sys_cols()

◆ trx_undo_update_rec_get_update()

Variable Documentation

◆ TRX_UNDO_CMPL_INFO_MULT

◆ TRX_UNDO_DEL_MARK_REC

◆ TRX_UNDO_GET_OLD_V_VALUE

◆ TRX_UNDO_INSERT_OP

◆ TRX_UNDO_INSERT_REC

◆ TRX_UNDO_MODIFY_BLOB

◆ TRX_UNDO_MODIFY_OP

◆ TRX_UNDO_PREV_IN_PURGE

◆ TRX_UNDO_UPD_DEL_REC

◆ TRX_UNDO_UPD_EXIST_REC

◆ TRX_UNDO_UPD_EXTERN