select @@global.innodb_stats_persistent;
@@global.innodb_stats_persistent
0
set global innodb_defragment_stats_accuracy = 20;
CREATE TABLE t1(a INT PRIMARY KEY, b VARCHAR(256), KEY SECOND(a, b))
ENGINE=INNODB;
INSERT INTO t1 SELECT seq, REPEAT('A', 256) FROM seq_1_to_1024;
# Not enough page splits to trigger persistent stats write yet.
select * from mysql.innodb_index_stats where table_name='t1'
and stat_name in ('n_page_split','n_pages_freed,n_leaf_pages_defrag');
database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description
INSERT INTO t1 SELECT seq, REPEAT('A', 256) FROM seq_1025_to_2048;
# Persistent stats recorded.
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select * from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_pages_freed');
database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
# Delete some rows.
delete from t1 where a between 100 * 20 and 100 * 20 + 30;
delete from t1 where a between 100 * 19 and 100 * 19 + 30;
delete from t1 where a between 100 * 18 and 100 * 18 + 30;
delete from t1 where a between 100 * 17 and 100 * 17 + 30;
delete from t1 where a between 100 * 16 and 100 * 16 + 30;
delete from t1 where a between 100 * 15 and 100 * 15 + 30;
delete from t1 where a between 100 * 14 and 100 * 14 + 30;
delete from t1 where a between 100 * 13 and 100 * 13 + 30;
delete from t1 where a between 100 * 12 and 100 * 12 + 30;
delete from t1 where a between 100 * 11 and 100 * 11 + 30;
delete from t1 where a between 100 * 10 and 100 * 10 + 30;
delete from t1 where a between 100 * 9 and 100 * 9 + 30;
delete from t1 where a between 100 * 8 and 100 * 8 + 30;
delete from t1 where a between 100 * 7 and 100 * 7 + 30;
delete from t1 where a between 100 * 6 and 100 * 6 + 30;
delete from t1 where a between 100 * 5 and 100 * 5 + 30;
delete from t1 where a between 100 * 4 and 100 * 4 + 30;
delete from t1 where a between 100 * 3 and 100 * 3 + 30;
delete from t1 where a between 100 * 2 and 100 * 2 + 30;
delete from t1 where a between 100 * 1 and 100 * 1 + 30;
# restart
# Server Restarted
# Confirm persistent stats still there after restart.
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select * from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_pages_freed');
database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
optimize table t1;
Table	Op	Msg_type	Msg_text
test.t1	optimize	status	OK
select sleep(2);
sleep(2)
0
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_pages_freed');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
set global innodb_defragment_stats_accuracy = 40;
INSERT INTO t1 SELECT seq, REPEAT('A', 256) FROM seq_2049_to_4096;
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_pages_freed');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
INSERT INTO t1 SELECT seq, REPEAT('A', 256) FROM seq_4097_to_8192;
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_pages_freed');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't1' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
# Table rename should cause stats rename.
rename table t1 to t2;
select * from mysql.innodb_index_stats where table_name = 't1';
database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't2' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't2' and  stat_name in ('n_pages_freed');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't2' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
# Drop index should cause stats drop.
drop index SECOND on t2;
select * from mysql.innodb_index_stats where table_name = 't2' and index_name = 'SECOND';
database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description
# restart
Server Restarted
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't2' and  stat_name in ('n_page_split');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't2' and  stat_name in ('n_pages_freed');
count(stat_value) > 0
1
select count(stat_value) > 0 from mysql.innodb_index_stats where table_name = 't2' and  stat_name in ('n_leaf_pages_defrag');
count(stat_value) > 0
1
# Clean up
DROP TABLE t2;
select * from mysql.innodb_index_stats where table_name = 't2';
database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description