mariadb/storage/innobase/include/dict0stats.h
Marko Mäkelä 4f8555f1f6 MDEV-14941 Timeouts on persistent statistics tables caused by MDEV-14511
MDEV-14511 tried to avoid some consistency problems related to InnoDB
persistent statistics. The persistent statistics are being written by
an InnoDB internal SQL interpreter that requires the InnoDB data dictionary
cache to be locked.

Before MDEV-14511, the statistics were written during DDL in separate
transactions, which could unnecessarily reduce performance (each commit
would require a redo log flush) and break atomicity, because the statistics
would be updated separately from the dictionary transaction.

However, because it is unacceptable to hold the InnoDB data dictionary
cache locked while suspending the execution for waiting for a
transactional lock (in the mysql.innodb_index_stats or
mysql.innodb_table_stats tables) to be released, any lock conflict
was immediately be reported as "lock wait timeout".

To fix MDEV-14941, an attempt to reduce these lock conflicts by acquiring
transactional locks on the user tables in both the statistics and DDL
operations was made, but it would still not entirely prevent lock conflicts
on the mysql.innodb_index_stats and mysql.innodb_table_stats tables.

Fixing the remaining problems would require a change that is too intrusive
for a GA release series, such as MariaDB 10.2.

Thefefore, we revert the change MDEV-14511. To silence the
MDEV-13201 assertion, we use the pre-existing flag trx_t::internal.
2018-01-22 08:58:47 +02:00

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/**************************************************//**
@file include/dict0stats.h
Code used for calculating and manipulating table statistics.
Created Jan 06, 2010 Vasil Dimov
*******************************************************/
#ifndef dict0stats_h
#define dict0stats_h
#include "univ.i"
#include "dict0types.h"
#include "trx0types.h"
enum dict_stats_upd_option_t {
DICT_STATS_RECALC_PERSISTENT,/* (re) calculate the
statistics using a precise and slow
algo and save them to the persistent
storage, if the persistent storage is
not present then emit a warning and
fall back to transient stats */
DICT_STATS_RECALC_TRANSIENT,/* (re) calculate the statistics
using an imprecise quick algo
without saving the results
persistently */
DICT_STATS_EMPTY_TABLE, /* Write all zeros (or 1 where it makes sense)
into a table and its indexes' statistics
members. The resulting stats correspond to an
empty table. If the table is using persistent
statistics, then they are saved on disk. */
DICT_STATS_FETCH_ONLY_IF_NOT_IN_MEMORY /* fetch the stats
from the persistent storage if the in-memory
structures have not been initialized yet,
otherwise do nothing */
};
/*********************************************************************//**
Set the persistent statistics flag for a given table. This is set only
in the in-memory table object and is not saved on disk. It will be read
from the .frm file upon first open from MySQL after a server restart. */
UNIV_INLINE
void
dict_stats_set_persistent(
/*======================*/
dict_table_t* table, /*!< in/out: table */
ibool ps_on, /*!< in: persistent stats explicitly enabled */
ibool ps_off) /*!< in: persistent stats explicitly disabled */
MY_ATTRIBUTE((nonnull));
/** @return whether persistent statistics is enabled for a given table */
UNIV_INLINE
bool
dict_stats_is_persistent_enabled(const dict_table_t* table)
MY_ATTRIBUTE((nonnull, warn_unused_result));
/*********************************************************************//**
Set the auto recalc flag for a given table (only honored for a persistent
stats enabled table). The flag is set only in the in-memory table object
and is not saved in InnoDB files. It will be read from the .frm file upon
first open from MySQL after a server restart. */
UNIV_INLINE
void
dict_stats_auto_recalc_set(
/*=======================*/
dict_table_t* table, /*!< in/out: table */
ibool auto_recalc_on, /*!< in: explicitly enabled */
ibool auto_recalc_off); /*!< in: explicitly disabled */
/** @return whether auto recalc is enabled for a given table*/
UNIV_INLINE
bool
dict_stats_auto_recalc_is_enabled(const dict_table_t* table)
MY_ATTRIBUTE((nonnull, warn_unused_result));
/*********************************************************************//**
Initialize table's stats for the first time when opening a table. */
UNIV_INLINE
void
dict_stats_init(
/*============*/
dict_table_t* table); /*!< in/out: table */
/*********************************************************************//**
Deinitialize table's stats after the last close of the table. This is
used to detect "FLUSH TABLE" and refresh the stats upon next open. */
UNIV_INLINE
void
dict_stats_deinit(
/*==============*/
dict_table_t* table) /*!< in/out: table */
MY_ATTRIBUTE((nonnull));
/** Update the table modification counter and if necessary,
schedule new estimates for table and index statistics to be calculated.
@param[in,out] table persistent or temporary table */
void
dict_stats_update_if_needed(dict_table_t* table)
MY_ATTRIBUTE((nonnull));
/*********************************************************************//**
Calculates new estimates for table and index statistics. The statistics
are used in query optimization.
@return DB_* error code or DB_SUCCESS */
dberr_t
dict_stats_update(
/*==============*/
dict_table_t* table, /*!< in/out: table */
dict_stats_upd_option_t stats_upd_option);
/*!< in: whether to (re) calc
the stats or to fetch them from
the persistent storage */
/*********************************************************************//**
Removes the information for a particular index's stats from the persistent
storage if it exists and if there is data stored for this index.
This function creates its own trx and commits it.
@return DB_SUCCESS or error code */
dberr_t
dict_stats_drop_index(
/*==================*/
const char* tname, /*!< in: table name */
const char* iname, /*!< in: index name */
char* errstr, /*!< out: error message if != DB_SUCCESS
is returned */
ulint errstr_sz);/*!< in: size of the errstr buffer */
/*********************************************************************//**
Removes the statistics for a table and all of its indexes from the
persistent storage if it exists and if there is data stored for the table.
This function creates its own transaction and commits it.
@return DB_SUCCESS or error code */
dberr_t
dict_stats_drop_table(
/*==================*/
const char* table_name, /*!< in: table name */
char* errstr, /*!< out: error message
if != DB_SUCCESS is returned */
ulint errstr_sz); /*!< in: size of errstr buffer */
/*********************************************************************//**
Fetches or calculates new estimates for index statistics. */
void
dict_stats_update_for_index(
/*========================*/
dict_index_t* index) /*!< in/out: index */
MY_ATTRIBUTE((nonnull));
/*********************************************************************//**
Renames a table in InnoDB persistent stats storage.
This function creates its own transaction and commits it.
@return DB_SUCCESS or error code */
dberr_t
dict_stats_rename_table(
/*====================*/
const char* old_name, /*!< in: old table name */
const char* new_name, /*!< in: new table name */
char* errstr, /*!< out: error string if != DB_SUCCESS
is returned */
size_t errstr_sz); /*!< in: errstr size */
#ifdef MYSQL_RENAME_INDEX
/*********************************************************************//**
Renames an index in InnoDB persistent stats storage.
This function creates its own transaction and commits it.
@return DB_SUCCESS or error code. DB_STATS_DO_NOT_EXIST will be returned
if the persistent stats do not exist. */
dberr_t
dict_stats_rename_index(
/*====================*/
const dict_table_t* table, /*!< in: table whose index
is renamed */
const char* old_index_name, /*!< in: old index name */
const char* new_index_name) /*!< in: new index name */
__attribute__((warn_unused_result));
#endif /* MYSQL_RENAME_INDEX */
/** Save an individual index's statistic into the persistent statistics
storage.
@param[in] index index to be updated
@param[in] last_update timestamp of the stat
@param[in] stat_name name of the stat
@param[in] stat_value value of the stat
@param[in] sample_size n pages sampled or NULL
@param[in] stat_description description of the stat
@param[in,out] trx in case of NULL the function will
allocate and free the trx object. If it is not NULL then it will be
rolled back only in the case of error, but not freed.
@return DB_SUCCESS or error code */
dberr_t
dict_stats_save_index_stat(
dict_index_t* index,
ib_time_t last_update,
const char* stat_name,
ib_uint64_t stat_value,
ib_uint64_t* sample_size,
const char* stat_description,
trx_t* trx);
/** Report an error if updating table statistics failed because
.ibd file is missing, table decryption failed or table is corrupted.
@param[in,out] table Table
@param[in] defragment true if statistics is for defragment
@retval DB_DECRYPTION_FAILED if decryption of the table failed
@retval DB_TABLESPACE_DELETED if .ibd file is missing
@retval DB_CORRUPTION if table is marked as corrupted */
dberr_t
dict_stats_report_error(dict_table_t* table, bool defragment = false)
MY_ATTRIBUTE((nonnull, warn_unused_result));
#include "dict0stats.ic"
#ifdef UNIV_ENABLE_UNIT_TEST_DICT_STATS
void test_dict_stats_all();
#endif /* UNIV_ENABLE_UNIT_TEST_DICT_STATS */
#endif /* dict0stats_h */