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Code Activity

MDEV-17255: New optimizer defaults and ANALYZE TABLE

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Added to new values to the server variable use_stat_tables.
The values are COMPLEMENTARY_FOR_QUERIES and PREFERABLY_FOR_QUERIES.
Both these values don't allow to collect EITS for queries like
    analyze table t1;
To collect EITS we would need to use the syntax with persistent like
   analyze table t1 persistent for columns (col1,col2...) index (idx1, idx2...) / ALL

Changing the default value from NEVER to PREFERABLY_FOR_QUERIES.
This commit is contained in:
Varun Gupta
2018-12-09 13:25:27 +05:30
parent 93c360e3a5
commit 9207a838ed
12 changed files with 199 additions and 16 deletions
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56
mysql-test/main/stat_tables.result
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@ -625,3 +625,59 @@ MAX(pk)
NULL
DROP TABLE t1;
set use_stat_tables=@save_use_stat_tables;
#
# MDEV-17255: New optimizer defaults and ANALYZE TABLE
#
create table t1 (a int, b int);
insert into t1(a,b) values (1,2),(1,3),(1,4),(1,5),(2,6),(2,7),(3,8),(3,9),(3,9),(4,10);
set use_stat_tables= preferably_for_queries;
#
# with use_stat_tables= PREFERABLY_FOR_QUERIES
# analyze table t1 will not collect statistics
#
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
select * from mysql.column_stats;
db_name table_name column_name min_value max_value nulls_ratio avg_length avg_frequency hist_size hist_type histogram
analyze
select * from t1 where a = 1 and b=3;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 10 10.00 100.00 10.00 Using where
#
# with use_stat_tables= PREFERABLY_FOR_QUERIES
# analyze table t1 will collect statistics if we use PERSISTENT
# for columns, indexes or everything
#
analyze table t1 persistent for columns (a) indexes ();
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status Table is already up to date
select * from mysql.column_stats;
db_name table_name column_name min_value max_value nulls_ratio avg_length avg_frequency hist_size hist_type histogram
test t1 a 1 4 0.0000 4.0000 2.5000 0 NULL NULL
# filtered shows that we used the data from stat tables
analyze
select * from t1 where a = 1 and b=3;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 10 10.00 25.00 10.00 Using where
#
# with use_stat_tables= PREFERABLY
# analyze table t1 will collect statistics
#
set use_stat_tables=PREFERABLY;
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status Table is already up to date
select * from mysql.column_stats;
db_name table_name column_name min_value max_value nulls_ratio avg_length avg_frequency hist_size hist_type histogram
test t1 a 1 4 0.0000 4.0000 2.5000 0 NULL NULL
test t1 b 2 10 0.0000 4.0000 1.1111 0 NULL NULL
# filtered shows that we used the data from stat tables
analyze
select * from t1 where a=1 and b=3;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 10 10.00 2.78 10.00 Using where
drop table t1;
set use_stat_tables=@save_use_stat_tables;