mariadb/storage/innobase/include/trx0purge.h
Sunny Bains 9d6d1902e0 Bug #11766227: InnoDB purge lag much worse for 5.5.8 versus 5.1
Bug #11766501: Multiple RBS break the get rseg with mininum trx_t::no code during purge
      
Bug# 59291 changes:
      
Main problem is that truncating the UNDO log at the completion of every
trx_purge() call is expensive as the number of rollback segments is increased.
We truncate after a configurable amount of pages. The innodb_purge_batch_size
parameter is used to control when InnoDB does the actual truncate. The truncate
is done once after 128 (or TRX_SYS_N_RSEGS iterations). In other words we
truncate after purge 128 * innodb_purge_batch_size. The smaller the batch
size the quicker we truncate.
      
Introduce a new parameter that allows how many rollback segments to use for
storing REDO information. This is really step 1 in allowing complete control
to the user over rollback space management.
      
New parameters:
    i) innodb_rollback_segments = number of rollback_segments to use
       (default is now 128) dynamic parameter, can be changed anytime.
       Currently there is little benefit in changing it from the default.
      
Optimisations in the patch.
      
    i. Change the O(n) behaviour of trx_rseg_get_on_id() to O(log n)
       Backported from 5.6. Refactor some of the binary heap code.
       Create a new include/ut0bh.ic file.
      
    ii. Avoid truncating the rollback segments after every purge.
      
Related changes that were moved to a separate patch:
      
    i. Purge should not do any flushing, only wait for space to be free so that
       it only does purging of records unless it is held up by a long running
       transaction that is preventing it from progressing.
      
   ii. Give the purge thread preference over transactions when acquiring the
       rseg->mutex during commit. This to avoid purge blocking unnecessarily
       when getting the next rollback segment to purge.
      
Bug #11766501 changes:
      
Add the rseg to the min binary heap under the cover of the kernel mutex and
the binary heap mutex. This ensures the ordering of the min binary heap.
      
The two changes have to be committed together because they share the same
that fixes both issues.
      
rb://567 Approved by: Inaam Rana.
2011-02-22 16:04:08 +11:00

197 lines
7.3 KiB
C

/*****************************************************************************
Copyright (c) 1996, 2011, Innobase Oy. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
*****************************************************************************/
/**************************************************//**
@file include/trx0purge.h
Purge old versions
Created 3/26/1996 Heikki Tuuri
*******************************************************/
#ifndef trx0purge_h
#define trx0purge_h
#include "univ.i"
#include "trx0types.h"
#include "mtr0mtr.h"
#include "trx0sys.h"
#include "que0types.h"
#include "page0page.h"
#include "usr0sess.h"
#include "fil0fil.h"
/** The global data structure coordinating a purge */
extern trx_purge_t* purge_sys;
/** A dummy undo record used as a return value when we have a whole undo log
which needs no purge */
extern trx_undo_rec_t trx_purge_dummy_rec;
/********************************************************************//**
Calculates the file address of an undo log header when we have the file
address of its history list node.
@return file address of the log */
UNIV_INLINE
fil_addr_t
trx_purge_get_log_from_hist(
/*========================*/
fil_addr_t node_addr); /*!< in: file address of the history
list node of the log */
/*****************************************************************//**
Checks if trx_id is >= purge_view: then it is guaranteed that its update
undo log still exists in the system.
@return TRUE if is sure that it is preserved, also if the function
returns FALSE, it is possible that the undo log still exists in the
system */
UNIV_INTERN
ibool
trx_purge_update_undo_must_exist(
/*=============================*/
trx_id_t trx_id);/*!< in: transaction id */
/********************************************************************//**
Creates the global purge system control structure and inits the history
mutex. */
UNIV_INTERN
void
trx_purge_sys_create(
/*=================*/
ib_bh_t* ib_bh); /*!< in/own: UNDO log min binary heap*/
/********************************************************************//**
Frees the global purge system control structure. */
UNIV_INTERN
void
trx_purge_sys_close(void);
/*======================*/
/************************************************************************
Adds the update undo log as the first log in the history list. Removes the
update undo log segment from the rseg slot if it is too big for reuse. */
UNIV_INTERN
void
trx_purge_add_update_undo_to_history(
/*=================================*/
trx_t* trx, /*!< in: transaction */
page_t* undo_page, /*!< in: update undo log header page,
x-latched */
mtr_t* mtr); /*!< in: mtr */
/********************************************************************//**
Fetches the next undo log record from the history list to purge. It must be
released with the corresponding release function.
@return copy of an undo log record or pointer to trx_purge_dummy_rec,
if the whole undo log can skipped in purge; NULL if none left */
UNIV_INTERN
trx_undo_rec_t*
trx_purge_fetch_next_rec(
/*=====================*/
roll_ptr_t* roll_ptr,/*!< out: roll pointer to undo record */
trx_undo_inf_t** cell, /*!< out: storage cell for the record in the
purge array */
mem_heap_t* heap); /*!< in: memory heap where copied */
/*******************************************************************//**
Releases a reserved purge undo record. */
UNIV_INTERN
void
trx_purge_rec_release(
/*==================*/
trx_undo_inf_t* cell); /*!< in: storage cell */
/*******************************************************************//**
This function runs a purge batch.
@return number of undo log pages handled in the batch */
UNIV_INTERN
ulint
trx_purge(
/*======*/
ulint limit); /*!< in: the maximum number of records to
purge in one batch */
/******************************************************************//**
Prints information of the purge system to stderr. */
UNIV_INTERN
void
trx_purge_sys_print(void);
/*======================*/
/** The control structure used in the purge operation */
struct trx_purge_struct{
ulint state; /*!< Purge system state */
sess_t* sess; /*!< System session running the purge
query */
trx_t* trx; /*!< System transaction running the
purge
query: this trx is not in the trx list
of the trx system and it never ends */
que_t* query; /*!< The query graph which will do the
parallelized purge operation */
rw_lock_t latch; /*!< The latch protecting the purge
view. A purge operation must acquire
an x-latch here for the instant at which
it changes the purge view: an undo
log operation can prevent this by
obtaining an s-latch here. */
read_view_t* view; /*!< The purge will not remove undo logs
which are >= this view (purge view) */
ulint n_pages_handled;/*!< Approximate number of undo log
pages processed in purge */
ulint handle_limit; /*!< Target of how many pages to get
processed in the current purge */
/*------------------------------*/
/* The following two fields form the 'purge pointer' which advances
during a purge, and which is used in history list truncation */
trx_id_t purge_trx_no; /*!< Purge has advanced past all
transactions whose number is less
than this */
undo_no_t purge_undo_no; /*!< Purge has advanced past all records
whose undo number is less than this */
/*-----------------------------*/
ibool next_stored; /*!< TRUE if the info of the next record
to purge is stored below: if yes, then
the transaction number and the undo
number of the record are stored in
purge_trx_no and purge_undo_no above */
trx_rseg_t* rseg; /*!< Rollback segment for the next undo
record to purge */
ulint page_no; /*!< Page number for the next undo
record to purge, page number of the
log header, if dummy record */
ulint offset; /*!< Page offset for the next undo
record to purge, 0 if the dummy
record */
ulint hdr_page_no; /*!< Header page of the undo log where
the next record to purge belongs */
ulint hdr_offset; /*!< Header byte offset on the page */
/*-----------------------------*/
trx_undo_arr_t* arr; /*!< Array of transaction numbers and
undo numbers of the undo records
currently under processing in purge */
mem_heap_t* heap; /*!< Temporary storage used during a
purge: can be emptied after purge
completes */
/*-----------------------------*/
ib_bh_t* ib_bh; /*!< Binary min-heap, ordered on
rseg_queue_t::trx_no. It is protected
by the bh_mutex */
mutex_t bh_mutex; /*!< Mutex protecting ib_bh */
};
#define TRX_PURGE_ON 1 /* purge operation is running */
#define TRX_STOP_PURGE 2 /* purge operation is stopped, or
it should be stopped */
#ifndef UNIV_NONINL
#include "trx0purge.ic"
#endif
#endif