From 1f28ee8875fdb8d868724b563ec959f76b54b28f Mon Sep 17 00:00:00 2001 From: Evgeny Potemkin Date: Wed, 27 Aug 2008 17:03:17 +0400 Subject: [PATCH] Bug#38195: Incorrect handling of aggregate functions when loose index scan is used causes server crash. When the loose index scan access method is used values of aggregated functions are precomputed by it. Aggregation of such functions shouldn't be performed in this case and functions should be treated as normal ones. The create_tmp_table function wasn't taking this into account and this led to a crash if a query has MIN/MAX aggregate functions and employs temporary table and loose index scan. Now the JOIN::exec and the create_tmp_table functions treat MIN/MAX aggregate functions as normal ones when the loose index scan is used. --- mysql-test/r/group_min_max.result | 76 +++++++++++++++++++++++++++++++ mysql-test/t/group_min_max.test | 19 ++++++++ sql/sql_select.cc | 5 +- 3 files changed, 99 insertions(+), 1 deletion(-) diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 5982931e677..f2f488650d5 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -2353,3 +2353,79 @@ a MIN(b) MAX(b) AVG(b) 2 1 3 2.0000 1 1 3 2.0000 DROP TABLE t1; +create table t1 (a int, b int, primary key (a,b), key `index` (a,b)) engine=MyISAM; +insert into t1 (a,b) values +(0,0),(0,1),(0,2),(0,3),(0,4),(0,5),(0,6), +(0,7),(0,8),(0,9),(0,10),(0,11),(0,12),(0,13), +(1,0),(1,1),(1,2),(1,3),(1,4),(1,5),(1,6), +(1,7),(1,8),(1,9),(1,10),(1,11),(1,12),(1,13), +(2,0),(2,1),(2,2),(2,3),(2,4),(2,5),(2,6), +(2,7),(2,8),(2,9),(2,10),(2,11),(2,12),(2,13), +(3,0),(3,1),(3,2),(3,3),(3,4),(3,5),(3,6), +(3,7),(3,8),(3,9),(3,10),(3,11),(3,12),(3,13); +insert into t1 (a,b) select a, max(b)+1 from t1 where a = 0 group by a; +select * from t1; +a b +0 0 +0 1 +0 2 +0 3 +0 4 +0 5 +0 6 +0 7 +0 8 +0 9 +0 10 +0 11 +0 12 +0 13 +0 14 +1 0 +1 1 +1 2 +1 3 +1 4 +1 5 +1 6 +1 7 +1 8 +1 9 +1 10 +1 11 +1 12 +1 13 +2 0 +2 1 +2 2 +2 3 +2 4 +2 5 +2 6 +2 7 +2 8 +2 9 +2 10 +2 11 +2 12 +2 13 +3 0 +3 1 +3 2 +3 3 +3 4 +3 5 +3 6 +3 7 +3 8 +3 9 +3 10 +3 11 +3 12 +3 13 +explain extended select sql_buffer_result a, max(b)+1 from t1 where a = 0 group by a; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 range PRIMARY,index PRIMARY 4 NULL 3 Using where; Using index for group-by; Using temporary +Warnings: +Note 1003 select sql_buffer_result `test`.`t1`.`a` AS `a`,(max(`test`.`t1`.`b`) + 1) AS `max(b)+1` from `test`.`t1` where (`test`.`t1`.`a` = 0) group by `test`.`t1`.`a` +drop table t1; diff --git a/mysql-test/t/group_min_max.test b/mysql-test/t/group_min_max.test index 7f2607b513d..f7aed7301fb 100644 --- a/mysql-test/t/group_min_max.test +++ b/mysql-test/t/group_min_max.test @@ -916,3 +916,22 @@ SELECT a, MIN(b), MAX(b), AVG(b) FROM t1 GROUP BY a ORDER BY a DESC; SELECT a, MIN(b), MAX(b), AVG(b) FROM t1 GROUP BY a ORDER BY a DESC; DROP TABLE t1; + +# +# Bug#38195: Incorrect handling of aggregate functions when loose index scan is +# used causes server crash. +# +create table t1 (a int, b int, primary key (a,b), key `index` (a,b)) engine=MyISAM; +insert into t1 (a,b) values +(0,0),(0,1),(0,2),(0,3),(0,4),(0,5),(0,6), + (0,7),(0,8),(0,9),(0,10),(0,11),(0,12),(0,13), +(1,0),(1,1),(1,2),(1,3),(1,4),(1,5),(1,6), + (1,7),(1,8),(1,9),(1,10),(1,11),(1,12),(1,13), +(2,0),(2,1),(2,2),(2,3),(2,4),(2,5),(2,6), + (2,7),(2,8),(2,9),(2,10),(2,11),(2,12),(2,13), +(3,0),(3,1),(3,2),(3,3),(3,4),(3,5),(3,6), + (3,7),(3,8),(3,9),(3,10),(3,11),(3,12),(3,13); +insert into t1 (a,b) select a, max(b)+1 from t1 where a = 0 group by a; +select * from t1; +explain extended select sql_buffer_result a, max(b)+1 from t1 where a = 0 group by a; +drop table t1; diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 6de4b296d34..6928effc1a5 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -1724,7 +1724,8 @@ JOIN::exec() if (!items1) { items1= items0 + all_fields.elements; - if (sort_and_group || curr_tmp_table->group) + if (sort_and_group || curr_tmp_table->group || + tmp_table_param.precomputed_group_by) { if (change_to_use_tmp_fields(thd, items1, tmp_fields_list1, tmp_all_fields1, @@ -9259,6 +9260,8 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List &fields, MI_COLUMNDEF *recinfo; uint total_uneven_bit_length= 0; bool force_copy_fields= param->force_copy_fields; + /* Treat sum functions as normal ones when loose index scan is used. */ + save_sum_fields|= param->precomputed_group_by; DBUG_ENTER("create_tmp_table"); DBUG_PRINT("enter",("distinct: %d save_sum_fields: %d rows_limit: %lu group: %d", (int) distinct, (int) save_sum_fields,