MDEV-6089 - MySQL WL#7305 "Improve MDL scalability by using lock-free hash"

Removed MDL map partitions. Won't be needed when this MDEV is implemented.

mysql-test/r/create_or_replace.result

@@ -264,8 +264,8 @@ select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	mysqltest2	
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	mysqltest2	
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	mysqltest2	t2
 create or replace table test.t1;
 ERROR 42000: A table must have at least 1 column
@@ -291,8 +291,8 @@ select * from information_schema.metadata_lock_info;
 THREAD_ID	LOCK_MODE	LOCK_DURATION	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Global read lock		
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	test	t1
-#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	mysqltest2	
 #	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	test	
+#	MDL_INTENTION_EXCLUSIVE	MDL_EXPLICIT	Schema metadata lock	mysqltest2	
 #	MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	Table metadata lock	mysqltest2	t2
 create or replace table test.t1 (a int) select 1 as 'a', 2 as 'a';
 ERROR 42S21: Duplicate column name 'a'

mysql-test/r/mysqld--help.result

@@ -454,7 +454,7 @@ The following options may be given as the first argument:
  --metadata-locks-cache-size=# 
  Unused
  --metadata-locks-hash-instances=# 
- Number of metadata locks hash instances
+ Unused
  --min-examined-row-limit=# 
  Don't write queries to slow log that examine fewer rows
  than that

mysql-test/suite/sys_vars/r/sysvars_server_embedded,32bit.rdiff

@@ -500,7 +500,7 @@
  VARIABLE_SCOPE	GLOBAL
 -VARIABLE_TYPE	BIGINT UNSIGNED
 +VARIABLE_TYPE	INT UNSIGNED
- VARIABLE_COMMENT	Number of metadata locks hash instances
+ VARIABLE_COMMENT	Unused
  NUMERIC_MIN_VALUE	1
  NUMERIC_MAX_VALUE	1024
 @@ -1987,7 +1987,7 @@

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -2002,7 +2002,7 @@ GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	8
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	BIGINT UNSIGNED
-VARIABLE_COMMENT	Number of metadata locks hash instances
+VARIABLE_COMMENT	Unused
 NUMERIC_MIN_VALUE	1
 NUMERIC_MAX_VALUE	1024
 NUMERIC_BLOCK_SIZE	1

mysql-test/suite/sys_vars/r/sysvars_server_notembedded,32bit.rdiff

@@ -500,7 +500,7 @@
  VARIABLE_SCOPE	GLOBAL
 -VARIABLE_TYPE	BIGINT UNSIGNED
 +VARIABLE_TYPE	INT UNSIGNED
- VARIABLE_COMMENT	Number of metadata locks hash instances
+ VARIABLE_COMMENT	Unused
  NUMERIC_MIN_VALUE	1
  NUMERIC_MAX_VALUE	1024
 @@ -2183,7 +2183,7 @@

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -2170,7 +2170,7 @@ GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	8
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	BIGINT UNSIGNED
-VARIABLE_COMMENT	Number of metadata locks hash instances
+VARIABLE_COMMENT	Unused
 NUMERIC_MIN_VALUE	1
 NUMERIC_MAX_VALUE	1024
 NUMERIC_BLOCK_SIZE	1

sql/mdl.h

@@ -981,14 +981,6 @@ extern "C" unsigned long thd_get_thread_id(const MYSQL_THD thd);
 extern "C" int thd_is_connected(MYSQL_THD thd);
 
 
-/*
-  Start-up parameter for the number of partitions of the hash
-  containing all the MDL_lock objects and a constant for
-  its default value.
-*/
-extern ulong mdl_locks_hash_partitions;
-static const ulong MDL_LOCKS_HASH_PARTITIONS_DEFAULT = 8;
-
 /*
   Metadata locking subsystem tries not to grant more than
   max_write_lock_count high-prio, strong locks successively,

sql/sys_vars.cc

@@ -1410,10 +1410,11 @@ static Sys_var_ulong Sys_metadata_locks_cache_size(
        VALID_RANGE(1, 1024*1024), DEFAULT(1024),
        BLOCK_SIZE(1));
 
+static ulong mdl_locks_hash_partitions;
 static Sys_var_ulong Sys_metadata_locks_hash_instances(
-       "metadata_locks_hash_instances", "Number of metadata locks hash instances",
+       "metadata_locks_hash_instances", "Unused",
        READ_ONLY GLOBAL_VAR(mdl_locks_hash_partitions), CMD_LINE(REQUIRED_ARG),
-       VALID_RANGE(1, 1024), DEFAULT(MDL_LOCKS_HASH_PARTITIONS_DEFAULT),
+       VALID_RANGE(1, 1024), DEFAULT(8),
        BLOCK_SIZE(1));
 
 /*