Description:
Hi,
I have data I am not expecting in INNODB_CMP. I traced this down to a regression introduced in 5.7.27, 8.0.28 not affected. See How to repeat for details.
Thanks for looking into this, Jean-François Gagné
How to repeat:
# Create a sandbox.
dbdeployer deploy single mysql_5.7.37
# Create schema, table and put data in them.
./use <<< "create database test_jfg"
./use test_jfg <<< "create table t (id int primary key, v int) KEY_BLOCK_SIZE=8"
./use test_jfg <<< "insert into t values (1,1)"
# Restart MySQL for reset of buffer pool.
./stop; ./start
# Read from the compressed table and check stats.
./use test_jfg <<< "select * from t" > /dev/null
./use information_schema <<< "select * from INNODB_CMP"
page_size compress_ops compress_ops_ok compress_time uncompress_ops uncompress_time
1024 0 0 0 0 0
2048 0 0 0 0 0
4096 0 0 0 0 0
8192 0 0 0 1 4838
16384 0 0 0 0 0
# The number 4838 is very high for an uncompress_time in seconds [1].
# [1]: https://dev.mysql.com/doc/refman/5.7/en/information-schema-innodb-cmp-table.html
# Same problem in 5.7.27.
[...]
page_size compress_ops compress_ops_ok compress_time uncompress_ops uncompress_time
1024 0 0 0 0 0
2048 0 0 0 0 0
4096 0 0 0 0 0
8192 0 0 0 1 6968
16384 0 0 0 0 0
# No problem in 5.7.26.
[...]
page_size compress_ops compress_ops_ok compress_time uncompress_ops uncompress_time
1024 0 0 0 0 0
2048 0 0 0 0 0
4096 0 0 0 0 0
8192 0 0 0 1 0
16384 0 0 0 0 0
# And no problem in 8.0.28.
page_size compress_ops compress_ops_ok compress_time uncompress_ops uncompress_time
1024 0 0 0 0 0
2048 0 0 0 0 0
4096 0 0 0 0 0
8192 0 0 0 1 0
16384 0 0 0 0 0
