Function make_join_statistics

sql/sql_select.cc:5648–6443

*/

static bool
make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
                     DYNAMIC_ARRAY *keyuse_array)
{
  int error= 0;
  uint i,table_count,const_count,key;
  uint sort_space;
  table_map found_const_table_map, all_table_map;
  key_map const_ref, eq_part;
  bool has_expensive_keyparts;
  TABLE **table_vector;
  JOIN_TAB *stat,*stat_end,*s,**stat_ref, **stat_vector;
  KEYUSE *keyuse,*start_keyuse;
  table_map outer_join=0;
  table_map no_rows_const_tables= 0;
  SARGABLE_PARAM *sargables= 0;
  List_iterator<TABLE_LIST> ti(tables_list);
  TABLE_LIST *tables;
  THD *thd= join->thd;
  DBUG_ENTER("make_join_statistics");

  table_count=join->table_count;
  const uint sj_nests= join->select_lex->sj_nests.elements; // Changed by pull-out

  /*
    best_extension_by_limited_search need sort space for 2POSITIION
    objects per remaining table, which gives us
    2*(T +  T-1 + T-2 + T-3...1 POSITIONS) = 2*(T+1)/2*T = (T*T+T)
  */
  join->sort_space= sort_space= (table_count*table_count + table_count);

  /*
    best_positions is ok to allocate with alloc() as we copy things to it with
    memcpy()
  */

  if (!multi_alloc_root(join->thd->mem_root,
                        &stat, sizeof(JOIN_TAB)*(table_count),
                        &stat_ref, sizeof(JOIN_TAB*)* MAX_TABLES,
                        &stat_vector, sizeof(JOIN_TAB*)* (table_count +1),
                        &table_vector, sizeof(TABLE*)*(table_count*2),
                        &join->positions, sizeof(POSITION)*(table_count + 1),
                        &join->sort_positions, sizeof(POSITION)*(sort_space),
                        &join->best_positions,
                        sizeof(POSITION)*(table_count + 1),
                        NullS))
    DBUG_RETURN(1);

  /* The following should be optimized to only clear critical things */
  bzero((void*)stat, sizeof(JOIN_TAB)* table_count);
  join->top_join_tab_count= table_count;

  /* Initialize POSITION objects */
  for (i=0 ; i <= table_count ; i++)
    (void) new ((char*) (join->positions + i)) POSITION;
  for (i=0 ; i < sort_space ; i++)
    (void) new ((char*) (join->sort_positions + i)) POSITION;