Purge old versions. More...

#include <sys/types.h>
#include <new>
#include <unordered_map>
#include "clone0api.h"
#include "clone0clone.h"
#include "dict0dd.h"
#include "fil0fil.h"
#include "fsp0fsp.h"
#include "fsp0sysspace.h"
#include "fsp0types.h"
#include "fut0fut.h"
#include "ha_prototypes.h"
#include "log0buf.h"
#include "log0chkp.h"
#include "mach0data.h"
#include "mtr0log.h"
#include "my_compiler.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "os0thread.h"
#include "que0que.h"
#include "read0read.h"
#include "row0purge.h"
#include "row0upd.h"
#include "srv0mon.h"
#include "srv0srv.h"
#include "srv0start.h"
#include "sync0sync.h"
#include "trx0purge.h"
#include "trx0rec.h"
#include "trx0roll.h"
#include "trx0rseg.h"
#include "trx0trx.h"

Classes
struct	Purge_groups_t

Namespaces
namespace	undo

Functions
static que_t *	trx_purge_graph_build (trx_t *trx, ulint n_purge_threads)
	Builds a purge 'query' graph. More...

void	trx_purge_sys_mem_create ()
	Initialize in-memory purge structures. More...

void	trx_purge_sys_initialize (uint32_t n_purge_threads, purge_pq_t *purge_queue)
	Creates the global purge system control structure and inits the history mutex. More...

void	trx_purge_sys_close ()
	Frees the global purge system control structure. More...

void	trx_purge_add_update_undo_to_history (trx_t trx, trx_undo_ptr_t undo_ptr, page_t undo_page, bool update_rseg_history_len, ulint n_added_logs, mtr_t mtr)
	Adds the update undo log as the first log in the history list. More...

static void	trx_purge_remove_log_hdr (trx_rsegf_t rseg_hdr, trx_ulogf_t log_hdr, mtr_t *mtr)
	Remove an rseg header from the history list. More...

static void	trx_purge_free_segment (trx_rseg_t *rseg, fil_addr_t hdr_addr, bool noredo)
	Frees a rollback segment which is in the history list. More...

static void	trx_purge_truncate_rseg_history (trx_rseg_t rseg, const purge_iter_t limit)
	Removes unnecessary history data from a rollback segment. More...

void	undo::init_space_id_bank ()
	Initialize the undo tablespace space_id bank which is a lock free repository for information about the space IDs used for undo tablespaces. More...

void	undo::use_space_id (space_id_t space_id)
	Note that the undo space number for a space ID is being used. More...

void	undo::unuse_space_id (space_id_t space_id)
	Mark an undo number associated with a given space_id as unused and available to be reused. More...

space_id_t	undo::next_space_id (space_id_t space_id, space_id_t space_num)
	Given a valid undo space_id or SPACE_UNKNOWN, return the next space_id for the given space number. More...

space_id_t	undo::next_space_id (space_id_t space_id)
	Given a valid undo space_id, return the next space_id for that space number. More...

space_id_t	undo::use_next_space_id (space_id_t space_num)
	Mark that the given undo space number is being used and return the next available space_id for that space number. More...

space_id_t	undo::get_next_available_space_num ()
	Return the next available undo space ID to be used for a new explicit undo tablespaces. More...

char *	undo::make_space_name (space_id_t space_id)
	Build a standard undo tablespace name from a space_id. More...

char *	undo::make_file_name (space_id_t space_id)
	Build a standard undo tablespace file name from a space_id. More...

void	undo::inject_crash (const char *injection_point_name)
	Inject a crash if a certain SET GLOBAL DEBUG has been set. More...

dberr_t	undo::start_logging (Tablespace *undo_space)
	Create the truncate log file. More...

void	undo::done_logging (space_id_t space_num)
	Mark completion of undo truncate action by writing magic number to the log file and then removing it from the disk. More...

bool	undo::is_active_truncate_log_present (space_id_t space_num)
	Check if TRUNCATE_DDL_LOG file exist. More...

void	undo::add_space_to_construction_list (space_id_t space_id)
	Add undo tablespace to s_under_construction vector. More...

void	undo::clear_construction_list ()
	Clear the s_under_construction vector. More...

bool	undo::is_under_construction (space_id_t space_id)
	Is an undo tablespace under construction at the moment. More...

void	undo::set_active (space_id_t space_id)
	Set an undo tablespace active. More...

bool	undo::is_active (space_id_t space_id, bool get_latch=true)

static bool	trx_purge_mark_undo_for_truncate (size_t truncate_count)
	Decide if an undo truncation needs to be done at this time. More...

static bool	trx_purge_check_if_marked_undo_is_empty ()
	Iterate over selected UNDO tablespace and check if all the rsegs that resides in the tablespace have been freed. More...

static bool	trx_purge_truncate_marked_undo_low (space_id_t space_num, std::string space_name)
	Truncate the marked undo tablespace. More...

static bool	trx_purge_truncate_marked_undo ()
	Truncate the marked undo tablespace. More...

static void	trx_purge_truncate_history (purge_iter_t limit, const ReadView view)
	Removes unnecessary history data from rollback segments. More...

static void	trx_purge_truncate_undo_spaces ()
	Select an undo tablespace to truncate, make sure it is empty of undo logs, then finally truncate it. More...

static void	trx_purge_rseg_get_next_history_log (trx_rseg_t rseg, ulint n_pages_handled)
	Updates the last not yet purged history log info in rseg when we have purged a whole undo log. More...

static void	trx_purge_read_undo_rec (trx_purge_t *purge_sys, const page_size_t &page_size)
	Position the purge sys "iterator" on the undo record to use for purging. More...

static void	trx_purge_choose_next_log (void)
	Chooses the next undo log to purge and updates the info in purge_sys. More...

static trx_undo_rec_t *	trx_purge_get_next_rec (ulint n_pages_handled, mem_heap_t heap)
	Gets the next record to purge and updates the info in the purge system. More...

static trx_undo_rec_t *	trx_purge_fetch_next_rec (trx_id_t modifier_trx_id, roll_ptr_t roll_ptr, ulint n_pages_handled, mem_heap_t heap)
	Fetches the next undo log record from the history list to purge. More...

static ulint	trx_purge_attach_undo_recs (const ulint n_purge_threads, ulint batch_size)
	This function runs a purge batch. More...

static ulint	trx_purge_dml_delay (void)
	Calculate the DML delay required. More...

static void	trx_purge_wait_for_workers_to_complete ()
	Wait for pending purge jobs to complete. More...

static void	trx_purge_truncate (void)
	Remove old historical changes from the rollback segments. More...

ulint	trx_purge (ulint n_purge_threads, ulint batch_size, bool truncate)
	This function runs a purge batch. More...

purge_state_t	trx_purge_state (void)
	Get the purge state. More...

void	trx_purge_stop (void)
	Stop purge and wait for it to stop, move to PURGE_STATE_STOP. More...

void	trx_purge_run (void)
	Resume purge, move to PURGE_STATE_RUN. More...

Variables
ulong	srv_max_purge_lag = 0
	Maximum allowable purge history length. More...

ulong	srv_max_purge_lag_delay = 0
	Max DML user threads delay in micro-seconds. More...

trx_purge_t *	purge_sys = nullptr
	The global data structure coordinating a purge. More...

static constexpr int64_t	PURGE_CHECK_UNDO_TRUNCATE_DELAY_IN_MS = 10
	Wait for a short delay between checks. More...

bool	srv_purge_view_update_only_debug

static trx_undo_rec_t	trx_purge_ignore_rec
	A sentinel undo record used as a return value when we have a whole undo log which can be skipped by purge. More...

Detailed Description

Purge old versions.

Created 3/26/1996 Heikki Tuuri

Function Documentation

◆ trx_purge()

ulint trx_purge	(	ulint	n_purge_threads,
		ulint	batch_size,
		bool	truncate
	)

This function runs a purge batch.

Returns: number of undo log pages handled in the batch

Parameters

n_purge_threads	in: number of purge tasks to submit to the work queue
batch_size	in: the maximum number of records to purge in one batch
truncate	in: truncate history if true

◆ trx_purge_add_update_undo_to_history()

void trx_purge_add_update_undo_to_history	(	trx_t *	trx,
		trx_undo_ptr_t *	undo_ptr,
		page_t *	undo_page,
		bool	update_rseg_history_len,
		ulint	n_added_logs,
		mtr_t *	mtr
	)

Adds the update undo log as the first log in the history list.

in: mtr

Removes the update undo log segment from the rseg slot if it is too big for reuse.

Parameters

trx	in: transaction
undo_ptr	in/out: update undo log.
undo_page	in: update undo log header page, x-latched
update_rseg_history_len	in: if true: update rseg history len else skip updating it.
n_added_logs	in: number of logs added
mtr	in: mtr

◆ trx_purge_attach_undo_recs()

static ulint trx_purge_attach_undo_recs	(	const ulint	n_purge_threads,
		ulint	batch_size
	)

static

This function runs a purge batch.

Parameters

[in]	n_purge_threads	number of purge threads
[in]	batch_size	number of pages to purge

Returns: number of undo log pages handled in the batch

◆ trx_purge_check_if_marked_undo_is_empty()

static bool trx_purge_check_if_marked_undo_is_empty ( )

static

Iterate over selected UNDO tablespace and check if all the rsegs that resides in the tablespace have been freed.

◆ trx_purge_choose_next_log()

static void trx_purge_choose_next_log ( void )

static

Chooses the next undo log to purge and updates the info in purge_sys.

This function is used to initialize purge_sys when the next record to purge is not known, and also to update the purge system info on the next record when purge has handled the whole undo log for a transaction.

◆ trx_purge_dml_delay()

static ulint trx_purge_dml_delay ( void )

static

Calculate the DML delay required.

Returns: delay in microseconds or ULINT_MAX

◆ trx_purge_fetch_next_rec()

static trx_undo_rec_t * trx_purge_fetch_next_rec	(	trx_id_t *	modifier_trx_id,
		roll_ptr_t *	roll_ptr,
		ulint *	n_pages_handled,
		mem_heap_t *	heap
	)

static

Fetches the next undo log record from the history list to purge.

It must be released with the corresponding release function.

Returns: copy of an undo log record or pointer to trx_purge_ignore_rec, if the whole undo log can skipped in purge; NULL if none left

Parameters

modifier_trx_id	out: modifier trx id. this is the trx that created the undo record.
roll_ptr	out: roll pointer to undo record
n_pages_handled	in/out: number of UNDO log pages handled
heap	in: memory heap where copied

◆ trx_purge_free_segment()

static void trx_purge_free_segment	(	trx_rseg_t *	rseg,
		fil_addr_t	hdr_addr,
		bool	noredo
	)

static

Frees a rollback segment which is in the history list.

Removes the rseg hdr from the history list.

Parameters

[in,out]	rseg	rollback segment
[in]	hdr_addr	file address of log_hdr
[in]	noredo	skip redo logging.

◆ trx_purge_get_next_rec()

static trx_undo_rec_t * trx_purge_get_next_rec	(	ulint *	n_pages_handled,
		mem_heap_t *	heap
	)

static

Gets the next record to purge and updates the info in the purge system.

Returns: copy of an undo log record or pointer to the dummy undo log record

Parameters

n_pages_handled	in/out: number of UNDO pages handled
heap	in: memory heap where copied

◆ trx_purge_graph_build()

static que_t * trx_purge_graph_build	(	trx_t *	trx,
		ulint	n_purge_threads
	)

static

Builds a purge 'query' graph.

The actual purge is performed by executing this query graph.

Parameters

[in]	trx	transaction
[in]	n_purge_threads	number of purge threads

Returns: own: the query graph

◆ trx_purge_mark_undo_for_truncate()

static bool trx_purge_mark_undo_for_truncate ( size_t truncate_count )

static

Decide if an undo truncation needs to be done at this time.

If an undo tablespace is already marked, return that so that this truncation will get finished. If none is marked, iterate over all the UNDO tablespaces and check if any qualify to be truncated. Normal operation; Choose the marked space. If none are marked, choose an explicitly inactive space. If none exist, check if conditions allow implicit truncation. If conditions allow, choose an implicitly inactive space. If none exist and no space has been truncated yet, look for an undo space that is too big. Fast shutdown; Do not truncate. This routine is not called. Slow shutdown; Choose the marked space. If none are marked, choose an explicitly inactive space. If none exist, check if conditions allow implicit truncation. If conditions allow, ignoring the previous truncate count, look for an undo space that is too big.

Parameters

[in] truncate_count number of times this is called in a loop

Returns: true if an undo tablespace was marked for truncate.

◆ trx_purge_read_undo_rec()

static void trx_purge_read_undo_rec	(	trx_purge_t *	purge_sys,
		const page_size_t &	page_size
	)

static

Position the purge sys "iterator" on the undo record to use for purging.

Parameters

[in,out]	purge_sys	purge instance
[in]	page_size	page size

◆ trx_purge_remove_log_hdr()

static void trx_purge_remove_log_hdr	(	trx_rsegf_t *	rseg_hdr,
		trx_ulogf_t *	log_hdr,
		mtr_t *	mtr
	)

static

Remove an rseg header from the history list.

Parameters

[in,out]	rseg_hdr	Rollback segment header
[in]	log_hdr	Undo log segment header
[in,out]	mtr	Mini-transaction.

◆ trx_purge_rseg_get_next_history_log()

static void trx_purge_rseg_get_next_history_log	(	trx_rseg_t *	rseg,
		ulint *	n_pages_handled
	)

static

Updates the last not yet purged history log info in rseg when we have purged a whole undo log.

Advances also purge_sys->purge_trx_no past the purged log.

Parameters

rseg	in: rollback segment
n_pages_handled	in/out: number of UNDO pages handled

◆ trx_purge_run()

void trx_purge_run ( void )

Resume purge, move to PURGE_STATE_RUN.

◆ trx_purge_state()

purge_state_t trx_purge_state ( void )

Get the purge state.

Returns: purge state.

◆ trx_purge_stop()

void trx_purge_stop ( void )

Stop purge and wait for it to stop, move to PURGE_STATE_STOP.

◆ trx_purge_sys_close()

void trx_purge_sys_close ( void )

Frees the global purge system control structure.

◆ trx_purge_sys_initialize()

void trx_purge_sys_initialize	(	uint32_t	n_purge_threads,
		purge_pq_t *	purge_queue
	)

Creates the global purge system control structure and inits the history mutex.

Parameters

[in]	n_purge_threads	number of purge threads
[in,out]	purge_queue	UNDO log min binary heap

◆ trx_purge_sys_mem_create()

void trx_purge_sys_mem_create ( )

Initialize in-memory purge structures.

◆ trx_purge_truncate()

static void trx_purge_truncate ( void )

static

Remove old historical changes from the rollback segments.

◆ trx_purge_truncate_history()

static void trx_purge_truncate_history	(	purge_iter_t *	limit,
		const ReadView *	view
	)

static

Removes unnecessary history data from rollback segments.

NOTE that when this function is called, the caller must not have any latches on undo log pages!

Parameters

[in]	limit	Truncate limit
[in]	view	Purge view

◆ trx_purge_truncate_marked_undo()

static bool trx_purge_truncate_marked_undo ( )

static

Truncate the marked undo tablespace.

This wrapper does initial preparation and handles cleanup.

Returns: true for success, false for failure

◆ trx_purge_truncate_marked_undo_low()

static bool trx_purge_truncate_marked_undo_low	(	space_id_t	space_num,
		std::string	space_name
	)

static

Truncate the marked undo tablespace.

This layer handles locking of marked_rsegs and undo::spaces.

Returns: true for success, false for failure

◆ trx_purge_truncate_rseg_history()

static void trx_purge_truncate_rseg_history	(	trx_rseg_t *	rseg,
		const purge_iter_t *	limit
	)

static

Removes unnecessary history data from a rollback segment.

Parameters

rseg	in: rollback segment
limit	in: truncate offset

◆ trx_purge_truncate_undo_spaces()

static void trx_purge_truncate_undo_spaces ( )

static

Select an undo tablespace to truncate, make sure it is empty of undo logs, then finally truncate it.

◆ trx_purge_wait_for_workers_to_complete()

static void trx_purge_wait_for_workers_to_complete ( )

static

Wait for pending purge jobs to complete.

Variable Documentation

◆ PURGE_CHECK_UNDO_TRUNCATE_DELAY_IN_MS

constexpr int64_t PURGE_CHECK_UNDO_TRUNCATE_DELAY_IN_MS = 10

staticconstexpr

Wait for a short delay between checks.

◆ purge_sys

trx_purge_t* purge_sys = nullptr

The global data structure coordinating a purge.

◆ srv_max_purge_lag

ulong srv_max_purge_lag = 0

Maximum allowable purge history length.

<=0 means 'infinite'.

◆ srv_max_purge_lag_delay

ulong srv_max_purge_lag_delay = 0

Max DML user threads delay in micro-seconds.

◆ srv_purge_view_update_only_debug

bool srv_purge_view_update_only_debug

◆ trx_purge_ignore_rec

trx_undo_rec_t trx_purge_ignore_rec

static

A sentinel undo record used as a return value when we have a whole undo log which can be skipped by purge.

Classes

Namespaces

Functions

Variables

Detailed Description

Function Documentation

◆ trx_purge()

◆ trx_purge_add_update_undo_to_history()

◆ trx_purge_attach_undo_recs()

◆ trx_purge_check_if_marked_undo_is_empty()

◆ trx_purge_choose_next_log()

◆ trx_purge_dml_delay()

◆ trx_purge_fetch_next_rec()

◆ trx_purge_free_segment()

◆ trx_purge_get_next_rec()

◆ trx_purge_graph_build()

◆ trx_purge_mark_undo_for_truncate()

◆ trx_purge_read_undo_rec()

◆ trx_purge_remove_log_hdr()

◆ trx_purge_rseg_get_next_history_log()

◆ trx_purge_run()

◆ trx_purge_state()

◆ trx_purge_stop()

◆ trx_purge_sys_close()

◆ trx_purge_sys_initialize()

◆ trx_purge_sys_mem_create()

◆ trx_purge_truncate()

◆ trx_purge_truncate_history()

◆ trx_purge_truncate_marked_undo()

◆ trx_purge_truncate_marked_undo_low()

◆ trx_purge_truncate_rseg_history()

◆ trx_purge_truncate_undo_spaces()

◆ trx_purge_wait_for_workers_to_complete()

Variable Documentation

◆ PURGE_CHECK_UNDO_TRUNCATE_DELAY_IN_MS

◆ purge_sys

◆ srv_max_purge_lag

◆ srv_max_purge_lag_delay

◆ srv_purge_view_update_only_debug

◆ trx_purge_ignore_rec