From 191c0c0b6ddf82e97f416f188392c4d7289b3878 Mon Sep 17 00:00:00 2001
From: MySQL Build Team <build@mysql.com>
Date: Tue, 22 Sep 2009 22:55:02 +0200
Subject: [PATCH] Backport into build-200909221805-5.1.37sp1
> ------------------------------------------------------------
> revno: 3059 [merge]
> revision-id: martin.hansson@sun.com-20090810140851-aw5peehzdxi4gjja
> parent: iggy@mysql.com-20090806145453-ion37sfdsldwwjrj
> parent: martin.hansson@sun.com-20090807115140-7fn6wjx0mrui7zl5
> committer: Martin Hansson <martin.hansson@sun.com>
> branch nick: 5.1bt
> timestamp: Mon 2009-08-10 16:08:51 +0200
> message:
> Merge
> ------------------------------------------------------------
> Use --include-merges or -n0 to see merged revisions.
---
mysql-test/r/order_by.result | 57 ++++++++++++++++++++++++++++++++++++
mysql-test/t/order_by.test | 41 ++++++++++++++++++++++++++
sql/sql_select.cc | 25 ++++++++--------
sql/table.h | 8 ++++-
4 files changed, 118 insertions(+), 13 deletions(-)
diff --git a/mysql-test/r/order_by.result b/mysql-test/r/order_by.result
index dc29c5ec226..306fce1f3c2 100644
--- a/mysql-test/r/order_by.result
+++ b/mysql-test/r/order_by.result
@@ -1500,3 +1500,60 @@ id1
15
16
DROP TABLE t1;
+CREATE TABLE t1 (
+a INT,
+b INT NOT NULL,
+c char(100),
+KEY (b, c),
+KEY (b, a, c)
+)
+DEFAULT CHARSET = utf8;
+INSERT INTO t1 VALUES
+(1, 1, 1),
+(2, 2, 2),
+(3, 3, 3),
+(4, 4, 4),
+(5, 5, 5),
+(6, 6, 6),
+(7, 7, 7),
+(8, 8, 8),
+(9, 9, 9);
+INSERT INTO t1 SELECT a + 10, b, c FROM t1;
+INSERT INTO t1 SELECT a + 20, b, c FROM t1;
+INSERT INTO t1 SELECT a + 40, b, c FROM t1;
+INSERT INTO t1 SELECT a + 80, b, c FROM t1;
+INSERT INTO t1 SELECT a + 160, b, c FROM t1;
+INSERT INTO t1 SELECT a + 320, b, c FROM t1;
+INSERT INTO t1 SELECT a + 640, b, c FROM t1;
+INSERT INTO t1 SELECT a + 1280, b, c FROM t1 LIMIT 80;
+EXPLAIN
+SELECT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 9;
+id select_type table type possible_keys key key_len ref rows Extra
+1 SIMPLE t1 range b,b_2 b 4 NULL 226 Using where
+SELECT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 9;
+a
+2071
+2061
+2051
+2041
+2031
+2021
+2011
+2001
+1991
+EXPLAIN
+SELECT DISTINCT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 0, 9;
+id select_type table type possible_keys key key_len ref rows Extra
+1 SIMPLE t1 range b,b_2 b 4 NULL 226 Using where; Using temporary
+SELECT DISTINCT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 0, 9;
+a
+2071
+2061
+2051
+2041
+2031
+2021
+2011
+2001
+1991
+DROP TABLE t1;
diff --git a/mysql-test/t/order_by.test b/mysql-test/t/order_by.test
index f09c1aa7bd4..cca1e3209cc 100644
--- a/mysql-test/t/order_by.test
+++ b/mysql-test/t/order_by.test
@@ -1361,3 +1361,44 @@ DROP TABLE t1;
+#
+# Bug#46454: MySQL wrong index optimisation leads to incorrect result & crashes
+#
+CREATE TABLE t1 (
+ a INT,
+ b INT NOT NULL,
+ c char(100),
+ KEY (b, c),
+ KEY (b, a, c)
+)
+DEFAULT CHARSET = utf8;
+
+INSERT INTO t1 VALUES
+(1, 1, 1),
+(2, 2, 2),
+(3, 3, 3),
+(4, 4, 4),
+(5, 5, 5),
+(6, 6, 6),
+(7, 7, 7),
+(8, 8, 8),
+(9, 9, 9);
+
+INSERT INTO t1 SELECT a + 10, b, c FROM t1;
+INSERT INTO t1 SELECT a + 20, b, c FROM t1;
+INSERT INTO t1 SELECT a + 40, b, c FROM t1;
+INSERT INTO t1 SELECT a + 80, b, c FROM t1;
+INSERT INTO t1 SELECT a + 160, b, c FROM t1;
+INSERT INTO t1 SELECT a + 320, b, c FROM t1;
+INSERT INTO t1 SELECT a + 640, b, c FROM t1;
+INSERT INTO t1 SELECT a + 1280, b, c FROM t1 LIMIT 80;
+
+EXPLAIN
+SELECT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 9;
+SELECT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 9;
+
+EXPLAIN
+SELECT DISTINCT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 0, 9;
+SELECT DISTINCT a FROM t1 WHERE b = 1 ORDER BY c DESC LIMIT 0, 9;
+
+DROP TABLE t1;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 401745bd9b8..b40ab8f71f4 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -6141,7 +6141,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
}
}
- if (tmp || !cond)
+ if (tmp || !cond || tab->type == JT_REF)
{
DBUG_EXECUTE("where",print_where(tmp,tab->table->alias, QT_ORDINARY););
SQL_SELECT *sel= tab->select= ((SQL_SELECT*)
@@ -6155,7 +6155,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
The guard will turn the predicate on only after
the first match for outer tables is encountered.
*/
- if (cond)
+ if (cond && tmp)
{
/*
Because of QUICK_GROUP_MIN_MAX_SELECT there may be a select without
@@ -12931,6 +12931,8 @@ find_field_in_item_list (Field *field, void *data)
The index must cover all fields in <order>, or it will not be considered.
+ @param no_changes No changes will be made to the query plan.
+
@todo
- sergeyp: Results of all index merge selects actually are ordered
by clustered PK values.
@@ -13265,6 +13267,15 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
}
if (!no_changes)
{
+ /*
+ If ref_key used index tree reading only ('Using index' in EXPLAIN),
+ and best_key doesn't, then revert the decision.
+ */
+ if (!table->covering_keys.is_set(best_key) && table->key_read)
+ {
+ table->key_read= 0;
+ table->file->extra(HA_EXTRA_NO_KEYREAD);
+ }
if (!quick_created)
{
tab->index= best_key;
@@ -13281,16 +13292,6 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
table->key_read=1;
table->file->extra(HA_EXTRA_KEYREAD);
}
- else if (table->key_read)
- {
- /*
- Clear the covering key read flags that might have been
- previously set for some key other than the current best_key.
- */
- table->key_read= 0;
- table->file->extra(HA_EXTRA_NO_KEYREAD);
- }
-
table->file->ha_index_or_rnd_end();
if (join->select_options & SELECT_DESCRIBE)
{
diff --git a/sql/table.h b/sql/table.h
index cb53013cd59..1d2ed294833 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -753,7 +753,13 @@ struct st_table {
*/
my_bool force_index;
my_bool distinct,const_table,no_rows;
- my_bool key_read, no_keyread;
+
+ /**
+ If set, the optimizer has found that row retrieval should access index
+ tree only.
+ */
+ my_bool key_read;
+ my_bool no_keyread;
/*
Placeholder for an open table which prevents other connections
from taking name-locks on this table. Typically used with
--
2.30.9