Now when a table is dropped the statistics on the table is removed
from the statistical tables. If the table is altered in such a way
that a column is dropped or the type of the column is changed then
statistics on the column is removed from the table column_stat.
It also triggers removal of the statistics on the indexes who use
this column as its component.
Added procedures that changes the names of the tables or columns
in the statistical tables for.
These procedures are used when tables/columns are renamed.
Also partly re-factored the code that introduced the persistent
statistical tables.
Added test cases into statistics.test to cover the new code.
Before this fix, the test myisam_file_io executed:
- (a) an update on setup_instrument to disable non myisam file io instruments
- (b) a truncate on events_waits_history_long
and later
- (c) a select on events_waits_history_long
Surprisingly, events that were supposed to be disabled in (a) and removed in (b)
still were found in (c).
This happened for events such as
wait/io/file/innodb/innodb_data_file fil0fil.c: sync
because the sync was started before (a) and completed after (b),
and as a consequence was added in the performance schema history, as expected.
Presence of these records in the history made the test fail.
This fix makes the test script more robust to account for extra spill waits records in (c).
Before this fix, the performance schema tables were defined in UPPERCASE.
This was incompatible with the lowercase_table_names option, and caused
issues with the install / upgrade process, when changing the lower case
table names setting *after* the install or upgrade.
With this fix, all performance schema tables are exposed with lowercase names.
As a result, the name of the performance schema table is always lowercase,
no matter how / if / when the lowercase_table_names setting if changed.
