Performed re-factoring and re-structuring of the code for mwl#248:

  - Moved the definitions of the classes to store data from persistent
    statistical tables into statistics.h, leaving in other internal 
    data structures only references to the corresponding objects.
  - Defined class Column_statistics_collected derived from the class
    Column_statistics. This is a helper class to collect statistics
    on columns.
  - Moved references to read statistics to TABLE SHARE, leaving the
    the reference to the collected statistics in TABLE.
 - Added a new clone method for the class Field allowing to clone
    fields attached to table shares. It was was used to create 
    fields for min/max values in the memory of the table share.
A lso:
  - Added procedures to allocate memory for statistical data in
    the table share memory and in table memory.
Also: 
  - Added a test case demonstrating how ANALYZE could work in parallel
    to collect statistics on different indexes of the same table.
  - Added a test two demonstrate how two connections working 
    simultaneously could allocate memory for statistical data in the 
    table share memory.  
   

1 files changed, 3 insertions, 0 deletions

diff --git a/sql/sql_base.h b/sql/sql_base.h
index 6c20022f7ee..a8d4951981e 100644
--- a/sql/sql_base.h
+++ b/sql/sql_base.h
@@ -314,6 +314,9 @@ int open_and_lock_tables_derived(THD *thd, TABLE_LIST *tables, bool derived);
 
 int read_statistics_for_table(THD *thd, TABLE *table);
 int collect_statistics_for_table(THD *thd, TABLE *table);
+int alloc_statistics_for_table_share(THD* thd, TABLE_SHARE *share,
+                                     bool is_safe);
+int alloc_statistics_for_table(THD *thd, TABLE *table);
 int update_statistics_for_table(THD *thd, TABLE *table);
 int delete_statistics_for_table(THD *thd, LEX_STRING *db, LEX_STRING *tab);
 int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col);