From 27bc13b7a2f99a6011a5081670b320c685dde443 Mon Sep 17 00:00:00 2001 From: Sergei Golubchik Date: Wed, 12 Jul 2017 19:31:01 +0200 Subject: MDEV-12136 SELECT COUNT(DISTINCT) returns the wrong value when tmp_table_size is limited Same MDEV, second bug. Merge buffer must fit at least MERGEBUFF2 (that is, 15) key values. Because merge_index() can merge that many buffers, and merge_many_buff() leaves that many buffers unmerged. --- mysql-test/r/count_distinct.result | 4 ++++ mysql-test/t/count_distinct.test | 2 ++ 2 files changed, 6 insertions(+) (limited to 'mysql-test') diff --git a/mysql-test/r/count_distinct.result b/mysql-test/r/count_distinct.result index 3decd5f60bc..d55a232c715 100644 --- a/mysql-test/r/count_distinct.result +++ b/mysql-test/r/count_distinct.result @@ -100,5 +100,9 @@ set @@tmp_table_size = 1024; select count(distinct user_id) from t1; count(distinct user_id) 17 +alter table t1 modify user_id char(128) character set utf8; +select count(distinct user_id) from t1; +count(distinct user_id) +17 drop table t1; set @@tmp_table_size = default; diff --git a/mysql-test/t/count_distinct.test b/mysql-test/t/count_distinct.test index ac97cdba357..a00574b6cba 100644 --- a/mysql-test/t/count_distinct.test +++ b/mysql-test/t/count_distinct.test @@ -115,6 +115,8 @@ create table t1 (user_id char(64) character set utf8); insert t1 values(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13),(14),(15),(16),(17); set @@tmp_table_size = 1024; select count(distinct user_id) from t1; +alter table t1 modify user_id char(128) character set utf8; +select count(distinct user_id) from t1; drop table t1; set @@tmp_table_size = default; -- cgit v1.2.1