- Column stat_value and sample_size in mysql.innodb_index_stats
table is declared as BIGINT UNSIGNED without any check constraint.
user manually updates the value of stat_value and sample_size
to zero. InnoDB aborts the server while reading the statistics
information because InnoDB expects at least one leaf
page to exist for the index.
- To fix this issue, InnoDB should interpret the value of
stat_n_leaf_pages, stat_index_size in innodb_index_stats
stat_clustered_index_size, stat_sum_of_other_index_sizes
in innodb_table_stats as valid one even though user
mentioned it as 0.
Problem:
=======
- When online alter of InnoDB statistics table happens,
any transaction which updates the statistics table
has to read the undo log and log the DML changes during
transaction commit. Applying undo log
(UndorecApplier::apply_undo_rec) requires a shared
lock on dictionary cache but dict_stats_save() already
holds write lock on dictionary cache. This leads to
abort of server during commit of statistics table changes.
Solution:
========
- Disallow LOCK=NONE operation for the InnoDB statistics table.
The reasoning is that statistics tables are typically
rather small, so any blocking would be rather short.
Writes to the statistics tables should be a rare operation.
Problem:
========
- InnoDB fails to free the allocated buffer of stored cursor
when information schema query is interrupted.
Solution:
=========
- In case of error handling, information schema query should free
the allocated buffer to store the cursor.
