From b87c342da5e51e112e06b36d8b95037f182bdb0e Mon Sep 17 00:00:00 2001 From: Varun Gupta Date: Fri, 29 Jan 2021 00:27:19 +0530 Subject: [PATCH] MDEV-11172: EXPLAIN shows non-sensical value for key_len with type=index The issue happens when the secondary keys are extended with primary key parts. Inside the function TABLE_SHARE::init_from_binary_frm_image() adds the length bytes for the primary key key parts to the length of the secondary key. This is not needed because when the extended keys are used we recalculate the length for the used key parts. Also removed TABLE_SHARE::total_key_length as it is not used in the code Apporved-by: Monty --- mysql-test/r/innodb_ext_key.result | 16 ++++++++++++++++ mysql-test/t/innodb_ext_key.test | 19 +++++++++++++++++++ sql/structs.h | 2 +- sql/table.cc | 10 ++++++++-- sql/table.h | 2 +- 5 files changed, 45 insertions(+), 4 deletions(-) diff --git a/mysql-test/r/innodb_ext_key.result b/mysql-test/r/innodb_ext_key.result index c7a5b1a80ca..880d7a8bceb 100644 --- a/mysql-test/r/innodb_ext_key.result +++ b/mysql-test/r/innodb_ext_key.result @@ -790,3 +790,19 @@ EXPLAIN } drop table t1; SET optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity; +# +# MDEV-11172: EXPLAIN shows non-sensical value for key_len with type=index +# +CREATE TABLE t1(a INT); +INSERT INTO t1 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); +CREATE TABLE t2 ( +pk VARCHAR(50), +a VARCHAR(20), +KEY k1(a), +PRIMARY KEY(pk) +)ENGINE=INNODB; +INSERT INTO t2 SELECT a,a FROM t1; +EXPLAIN SELECT pk FROM t2 FORCE INDEX(k1); +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t2 index NULL k1 23 NULL 10 Using index +DROP TABLE t1,t2; diff --git a/mysql-test/t/innodb_ext_key.test b/mysql-test/t/innodb_ext_key.test index f5edd736490..de9ca10ff1b 100644 --- a/mysql-test/t/innodb_ext_key.test +++ b/mysql-test/t/innodb_ext_key.test @@ -606,3 +606,22 @@ explain format= json select * from t1 force index(k1) where f2 <= 5 and pk2 <=5 and pk1 = 'abc' and f1 <= '3'; drop table t1; SET optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity; + +--echo # +--echo # MDEV-11172: EXPLAIN shows non-sensical value for key_len with type=index +--echo # + +CREATE TABLE t1(a INT); +INSERT INTO t1 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); + +CREATE TABLE t2 ( + pk VARCHAR(50), + a VARCHAR(20), + KEY k1(a), + PRIMARY KEY(pk) +)ENGINE=INNODB; + +INSERT INTO t2 SELECT a,a FROM t1; +EXPLAIN SELECT pk FROM t2 FORCE INDEX(k1); + +DROP TABLE t1,t2; diff --git a/sql/structs.h b/sql/structs.h index 67fb0d5dd66..27b9725815b 100644 --- a/sql/structs.h +++ b/sql/structs.h @@ -90,7 +90,7 @@ class engine_option_value; struct ha_index_option_struct; typedef struct st_key { - uint key_length; /* Tot length of key */ + uint key_length; /* total length of user defined key parts */ ulong flags; /* dupp key and pack flags */ uint user_defined_key_parts; /* How many key_parts */ uint usable_key_parts; /* Should normally be = user_defined_key_parts */ diff --git a/sql/table.cc b/sql/table.cc index e4492f21a30..1004f583448 100644 --- a/sql/table.cc +++ b/sql/table.cc @@ -2273,6 +2273,12 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write, key_part->null_bit= field->null_bit; key_part->store_length+=HA_KEY_NULL_LENGTH; keyinfo->flags|=HA_NULL_PART_KEY; + + /* + This branch is executed only for user defined key parts of the + secondary indexes. + */ + DBUG_ASSERT(i < keyinfo->user_defined_key_parts); keyinfo->key_length+= HA_KEY_NULL_LENGTH; } if (field->type() == MYSQL_TYPE_BLOB || @@ -2285,7 +2291,8 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write, else key_part->key_part_flag|= HA_VAR_LENGTH_PART; key_part->store_length+=HA_KEY_BLOB_LENGTH; - keyinfo->key_length+= HA_KEY_BLOB_LENGTH; + if (i < keyinfo->user_defined_key_parts) + keyinfo->key_length+= HA_KEY_BLOB_LENGTH; } if (field->type() == MYSQL_TYPE_BIT) key_part->key_part_flag|= HA_BIT_PART; @@ -2378,7 +2385,6 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write, set_if_bigger(share->max_key_length,keyinfo->key_length+ keyinfo->user_defined_key_parts); - share->total_key_length+= keyinfo->key_length; /* MERGE tables do not have unique indexes. But every key could be an unique index on the underlying MyISAM table. (Bug #10400) diff --git a/sql/table.h b/sql/table.h index a5d412c2c08..83c72f76831 100644 --- a/sql/table.h +++ b/sql/table.h @@ -773,7 +773,7 @@ struct TABLE_SHARE uint rec_buff_length; /* Size of table->record[] buffer */ uint keys, key_parts; uint ext_key_parts; /* Total number of key parts in extended keys */ - uint max_key_length, max_unique_length, total_key_length; + uint max_key_length, max_unique_length; uint uniques; /* Number of UNIQUE index */ uint db_create_options; /* Create options from database */ uint db_options_in_use; /* Options in use */