diff options
Diffstat (limited to 'storage/innodb_plugin/handler/ha_innodb.cc')
| -rw-r--r-- | storage/innodb_plugin/handler/ha_innodb.cc | 95 |
1 files changed, 88 insertions, 7 deletions
diff --git a/storage/innodb_plugin/handler/ha_innodb.cc b/storage/innodb_plugin/handler/ha_innodb.cc index 18a25fd8c4e..481b89ce0d1 100644 --- a/storage/innodb_plugin/handler/ha_innodb.cc +++ b/storage/innodb_plugin/handler/ha_innodb.cc @@ -174,6 +174,25 @@ static char* internal_innobase_data_file_path = NULL; static char* innodb_version_str = (char*) INNODB_VERSION_STR; +/** Possible values for system variable "innodb_stats_method". The values +are defined the same as its corresponding MyISAM system variable +"myisam_stats_method"(see "myisam_stats_method_names"), for better usability */ +static const char* innodb_stats_method_names[] = { + "nulls_equal", + "nulls_unequal", + "nulls_ignored", + NullS +}; + +/** Used to define an enumerate type of the system variable innodb_stats_method. +This is the same as "myisam_stats_method_typelib" */ +static TYPELIB innodb_stats_method_typelib = { + array_elements(innodb_stats_method_names) - 1, + "innodb_stats_method_typelib", + innodb_stats_method_names, + NULL +}; + /* The following counter is used to convey information to InnoDB about server activity: in selects it is not sensible to call srv_active_wake_master_thread after each fetch or search, we only do @@ -7518,6 +7537,65 @@ innobase_get_mysql_key_number_for_index( return(0); } + +/*********************************************************************//** +Calculate Record Per Key value. Need to exclude the NULL value if +innodb_stats_method is set to "nulls_ignored" +@return estimated record per key value */ +static +ha_rows +innodb_rec_per_key( +/*===============*/ + dict_index_t* index, /*!< in: dict_index_t structure */ + ulint i, /*!< in: the column we are + calculating rec per key */ + ha_rows records) /*!< in: estimated total records */ +{ + ha_rows rec_per_key; + + ut_ad(i < dict_index_get_n_unique(index)); + + /* Note the stat_n_diff_key_vals[] stores the diff value with + n-prefix indexing, so it is always stat_n_diff_key_vals[i + 1] */ + if (index->stat_n_diff_key_vals[i + 1] == 0) { + + rec_per_key = records; + } else if (srv_innodb_stats_method == SRV_STATS_NULLS_IGNORED) { + ib_int64_t num_null; + + /* Number of rows with NULL value in this + field */ + num_null = records - index->stat_n_non_null_key_vals[i]; + + /* In theory, index->stat_n_non_null_key_vals[i] + should always be less than the number of records. + Since this is statistics value, the value could + have slight discrepancy. But we will make sure + the number of null values is not a negative number. */ + num_null = (num_null < 0) ? 0 : num_null; + + /* If the number of NULL values is the same as or + large than that of the distinct values, we could + consider that the table consists mostly of NULL value. + Set rec_per_key to 1. */ + if (index->stat_n_diff_key_vals[i + 1] <= num_null) { + rec_per_key = 1; + } else { + /* Need to exclude rows with NULL values from + rec_per_key calculation */ + rec_per_key = (ha_rows)( + (records - num_null) + / (index->stat_n_diff_key_vals[i + 1] + - num_null)); + } + } else { + rec_per_key = (ha_rows) + (records / index->stat_n_diff_key_vals[i + 1]); + } + + return(rec_per_key); +} + /*********************************************************************//** Returns statistics information of the table to the MySQL interpreter, in various fields of the handle object. */ @@ -7748,13 +7826,8 @@ ha_innobase::info_low( break; } - if (index->stat_n_diff_key_vals[j + 1] == 0) { - - rec_per_key = stats.records; - } else { - rec_per_key = (ha_rows)(stats.records / - index->stat_n_diff_key_vals[j + 1]); - } + rec_per_key = innodb_rec_per_key( + index, j, stats.records); /* Since MySQL seems to favor table scans too much over index searches, we pretend @@ -10945,6 +11018,13 @@ static MYSQL_SYSVAR_STR(change_buffering, innobase_change_buffering, innodb_change_buffering_validate, innodb_change_buffering_update, "inserts"); +static MYSQL_SYSVAR_ENUM(stats_method, srv_innodb_stats_method, + PLUGIN_VAR_RQCMDARG, + "Specifies how InnoDB index statistics collection code should " + "treat NULLs. Possible values are NULLS_EQUAL (default), " + "NULLS_UNEQUAL and NULLS_IGNORED", + NULL, NULL, SRV_STATS_NULLS_EQUAL, &innodb_stats_method_typelib); + #if defined UNIV_DEBUG || defined UNIV_IBUF_DEBUG static MYSQL_SYSVAR_UINT(change_buffering_debug, ibuf_debug, PLUGIN_VAR_RQCMDARG, @@ -10999,6 +11079,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= { MYSQL_SYSVAR(stats_on_metadata), MYSQL_SYSVAR(stats_sample_pages), MYSQL_SYSVAR(adaptive_hash_index), + MYSQL_SYSVAR(stats_method), MYSQL_SYSVAR(replication_delay), MYSQL_SYSVAR(status_file), MYSQL_SYSVAR(strict_mode), |