MDEV-19574 innodb_stats_method is not honored when innodb_stats_persistent=ON #4204
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dr-m
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Jul 16, 2025
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msan failure is MDEV-28165 |
Thirunarayanan
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dr-m
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| CREATE TABLE t1(f1 INT NOT NULL, f2 INT NOT NULL, | ||
| f3 INT, KEY(f1, f3), key(f3)) STATS_PERSISTENT=1,ENGINE=INNODB; | ||
| INSERT INTO t1 SELECT seq, seq, NULL from seq_1_to_16384; | ||
| ANALYZE TABLE t1; |
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Could we cover this for the maximum number of index columns, similar to how 464055f extended the test innodb.purge? I think that the maximum would be with a 32-column PRIMARY KEY and a 32-column non-unique secondary index.
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| dict_stats_analyze_index_for_n_prefix( | ||
| dict_index_t* index, | ||
| ulint n_prefix, | ||
| bool nulls_unequal, | ||
| bool calc_non_null, | ||
| const boundaries_t* boundaries, | ||
| n_diff_data_t* n_diff_data, | ||
| mtr_t* mtr) |
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Could we pass fewer parameters here? Could IndexScanStatistics or something similar be used here as well?
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| static | ||
| void | ||
| dict_stats_analyze_index_below_cur( | ||
| const btr_cur_t* cur, | ||
| ulint n_prefix, | ||
| bool nulls_unequal, | ||
| ib_uint64_t* n_diff, | ||
| ib_uint64_t* n_external_pages) | ||
| ib_uint64_t* n_external_pages, | ||
| ib_uint64_t* n_non_null) |
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Could we pass fewer parameters here? Can IndexScanStatistics or something similar be used here?
…stent=ON Problem: ======= InnoDB persistent statistics doesn't take innodb_stats_method variable while calculating n_diff_pfx for the n-prefix index columns. Solution: ========= While calculating the persistent statistics, InnoDB consider all NULLS as different value when innodb_stats_method is set to NULLS_UNEQUAL or NULLS_IGNORED. InnoDB statistics depends on the value of "innodb_stats_method" variable when the statistics were last recalculated. dict_stats_analyze_index_level(), dict_stats_scan_page(), dict_stats_analyze_index_below_cur(), dict_stats_analyze_index_for_n_prefix(): All function accepts the parameter to indicate the innodb_stats_method. It also calculates the number of non-null key value for each level or leaf page dict_stats_index_set_n_diff(): calculates the number of non-null values similar to number of different key values. Append the non-default innodb_stats_method variable name for n_diff_pfx statistics description in mysql.innodb_index_stats. IndexScanStatistics: Structure to store the various statistical metric gathered during index scan fetch operation. This structure is being used in dict_stats_analyze_index_level() to fetch the statistics
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Description
Problem:
InnoDB persistent statistics doesn't take innodb_stats_method
variable while calculating n_diff_pfx for the n-prefix index columns.
Solution:
While calculating the persistent statistics, InnoDB consider all NULLS as different value when innodb_stats_method is set to NULLS_UNEQUAL or NULLS_IGNORED. InnoDB statistics depends on the value of "innodb_stats_method" variable when the statistics were last recalculated.
dict_stats_analyze_index_level(),
dict_stats_scan_page(),
dict_stats_analyze_index_below_cur(),
dict_stats_analyze_index_for_n_prefix(): All function accepts the parameter to indicate the innodb_stats_method. It also calculates the number of non-null key value for each level or leaf page
dict_stats_index_set_n_diff(): calculates the number of non-null values similar to number of different key values.
Append the innodb_stats_method variable name for n_diff_pfx statistics description in mysql.innodb_index_stats.
Release Notes
InnoDB persisent statistics is stored in mysql.innodb_index_stats based on innodb_stats_method variable
How can this PR be tested?
./mtr innodb.innodb_stats_method
Basing the PR against the correct MariaDB version
mainbranch.PR quality check