engine-independent statistics.
When the primary key was dropped or changed statistics on secondary
indexes for the prefixes that included components of the primary
key was not removed from the table mysql.index_stats.
Also fixed: in the some cases when a column was changed statistics
on the indexes that included this column was not removed from the
table mysql.index_stats.
Also disabled the test mdev-504 for --ps-protocol.
1. The PERSISTENT FOR clause of the ANALYZE command overrides
the setting of the system variable use_stat_tables:
with this clause ANALYZE unconditionally collects persistent
statistics.
2. ANALYZE collects persistent statistics only for tables of
the USER category. So it never collects persistent statistics
for system tables.
table_stat -> table_stats
column_stat -> column_stats
index_stat -> index_stats
to be in line with the names of innodb statistical tables
from mysql-5.6: innodb_table_stats and innodb_index_stats.
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.
mysql.column_stat, mysql.table_stat for the type DECIMAL(12,4).
When cached the values from these columns are multiplied by factor 10^5
and stored as ulong numbers now.
Renamed the system variable optimizer_use_stat_tables to use_stat_tables.
This variable now has only 3 possible values:
'never', 'complementary', 'preferably'.
If the server has been launched with
--use-stat-tables='complementary'|'preferably'
then the statictics tables can be employed by the optimizer and by the
ANALYZE command.
