diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 89 |
1 files changed, 64 insertions, 25 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 450efb84e5d..b7eebf80313 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -136,7 +136,8 @@ static void copy_sum_funcs(Item_sum **func_ptr); static bool add_ref_to_table_cond(THD *thd, JOIN_TAB *join_tab); static void init_sum_functions(Item_sum **func); static bool update_sum_func(Item_sum **func); -static void select_describe(JOIN *join, bool need_tmp_table, bool need_order); +static void select_describe(JOIN *join, bool need_tmp_table, bool need_order, + bool distinct); static void describe_info(const char *info); /***************************************************************************** @@ -171,6 +172,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds, no_order=0; bzero((char*) &keyuse,sizeof(keyuse)); thd->proc_info="init"; + thd->used_tables=0; // Updated by setup_fields if (setup_fields(thd,tables,fields,1,&all_fields) || setup_conds(thd,tables,&conds) || @@ -261,7 +263,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds, join.join_tab=0; join.tmp_table_param.copy_field=0; join.sum_funcs=0; - join.send_records=0L; + join.send_records=join.found_records=0; join.tmp_table_param.end_write_records= HA_POS_ERROR; join.first_record=join.sort_and_group=0; join.select_options=select_options; @@ -506,7 +508,8 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds, order=0; select_describe(&join,need_tmp, (order != 0 && - (!need_tmp || order != group || simple_group))); + (!need_tmp || order != group || simple_group)), + select_distinct); error=0; goto err; } @@ -557,6 +560,26 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds, order=0; } } + + /* + Optimize distinct when used on some of the tables + SELECT DISTINCT t1.a FROM t1,t2 WHERE t1.b=t2.b + In this case we can stop scanning t2 when we have found one t1.a + */ + + if (tmp_table->distinct) + { + table_map used_tables= thd->used_tables; + JOIN_TAB *join_tab=join.join_tab+join.tables-1; + do + { + if (used_tables & join_tab->table->map) + break; + join_tab->not_used_in_distinct=1; + } while (join_tab-- != join.join_tab); + } + + /* Copy data to the temporary table */ thd->proc_info="Copying to tmp table"; if (do_select(&join,(List<Item> *) 0,tmp_table,0)) goto err; /* purecov: inspected */ @@ -2122,7 +2145,7 @@ make_simple_join(JOIN *join,TABLE *tmp_table) join->tmp_table_param.copy_field=0; join->first_record=join->sort_and_group=0; join->sum_funcs=0; - join->send_records=0L; + join->send_records=(ha_rows) 0; join->group=0; join_tab->cache.buff=0; /* No cacheing */ @@ -2130,15 +2153,16 @@ make_simple_join(JOIN *join,TABLE *tmp_table) join_tab->select=0; join_tab->select_cond=0; join_tab->quick=0; - bzero((char*) &join_tab->read_record,sizeof(join_tab->read_record)); join_tab->type= JT_ALL; /* Map through all records */ join_tab->keys= (uint) ~0; /* test everything in quick */ join_tab->info=0; join_tab->on_expr=0; join_tab->ref.key = -1; + join_tab->not_used_in_distinct=0; + join_tab->read_first_record= join_init_read_record; + bzero((char*) &join_tab->read_record,sizeof(join_tab->read_record)); tmp_table->status=0; tmp_table->null_row=0; - join_tab->read_first_record= join_init_read_record; return FALSE; } @@ -3256,7 +3280,6 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields, if (item->with_sum_func && type != Item::SUM_FUNC_ITEM || item->const_item()) continue; - if (type == Item::SUM_FUNC_ITEM && !group && !save_sum_fields) { /* Can't calc group yet */ ((Item_sum*) item)->result_field=0; @@ -3913,7 +3936,9 @@ sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records) if (!(error=(*join_tab->read_first_record)(join_tab))) { - bool not_exists_optimize=join_tab->table->reginfo.not_exists_optimize; + bool not_exists_optimize= join_tab->table->reginfo.not_exists_optimize; + bool not_used_in_distinct=join_tab->not_used_in_distinct; + ha_rows found_records=join->found_records; READ_RECORD *info= &join_tab->read_record; do @@ -3932,6 +3957,8 @@ sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records) { if ((error=(*next_select)(join,join_tab+1,0)) < 0) return error; + if (not_used_in_distinct && found_records != join->found_records) + return 0; } } } while (!(error=info->read_record(info))); @@ -4545,23 +4572,21 @@ end_write(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)), } if (!join->having || join->having->val_int()) { + join->found_records++; if ((error=table->file->write_row(table->record[0]))) { - if (error != HA_ERR_FOUND_DUPP_KEY && - error != HA_ERR_FOUND_DUPP_UNIQUE) - { - if (create_myisam_from_heap(table, &join->tmp_table_param, error,1)) - DBUG_RETURN(1); // Not a table_is_full error - table->uniques=0; // To ensure rows are the same - } - } - else - { + if (error == HA_ERR_FOUND_DUPP_KEY || + error == HA_ERR_FOUND_DUPP_UNIQUE) + goto end; + if (create_myisam_from_heap(table, &join->tmp_table_param, error,1)) + DBUG_RETURN(1); // Not a table_is_full error + table->uniques=0; // To ensure rows are the same if (++join->send_records >= join->tmp_table_param.end_write_records) DBUG_RETURN(-3); } } } +end: DBUG_RETURN(0); } @@ -4585,6 +4610,7 @@ end_update(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)), DBUG_RETURN(-2); /* purecov: inspected */ } + join->found_records++; copy_fields(&join->tmp_table_param); // Groups are copied twice. /* Make a key of group index */ for (group=table->group ; group ; group=group->next) @@ -6335,12 +6361,13 @@ static bool add_ref_to_table_cond(THD *thd, JOIN_TAB *join_tab) ** Send a description about what how the select will be done to stdout ****************************************************************************/ -static void select_describe(JOIN *join, bool need_tmp_table, bool need_order) +static void select_describe(JOIN *join, bool need_tmp_table, bool need_order, + bool distinct) { - DBUG_ENTER("select_describe"); - List<Item> field_list; Item *item; + THD *thd=join->thd; + DBUG_ENTER("select_describe"); field_list.push_back(new Item_empty_string("table",NAME_LEN)); field_list.push_back(new Item_empty_string("type",10)); @@ -6356,11 +6383,12 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order) item->maybe_null=1; field_list.push_back(new Item_real("rows",0.0,0,10)); field_list.push_back(new Item_empty_string("Extra",255)); - if (send_fields(join->thd,field_list,1)) + if (send_fields(thd,field_list,1)) return; /* purecov: inspected */ char buff[512],*buff_ptr; - String tmp(buff,sizeof(buff)),*packet= &join->thd->packet; + String tmp(buff,sizeof(buff)),*packet= &thd->packet; + table_map used_tables=0; for (uint i=0 ; i < join->tables ; i++) { JOIN_TAB *tab=join->join_tab+i; @@ -6473,11 +6501,22 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order) } buff_ptr=strmov(buff_ptr,"Using filesort"); } + if (distinct & test_all_bits(used_tables,thd->used_tables)) + { + if (buff != buff_ptr) + { + buff_ptr[0]=';' ; buff_ptr[1]=' '; buff_ptr+=2; + } + buff_ptr=strmov(buff_ptr,"Distinct"); + } net_store_data(packet,buff,(uint) (buff_ptr - buff)); - if (my_net_write(&join->thd->net,(char*) packet->ptr(),packet->length())) + if (my_net_write(&thd->net,(char*) packet->ptr(),packet->length())) DBUG_VOID_RETURN; /* purecov: inspected */ + + // For next iteration + used_tables|=table->map; } - send_eof(&join->thd->net); + send_eof(&thd->net); DBUG_VOID_RETURN; } |