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MDEV-35889 set information_schema.system_variables NUMERIC_MIN_VALUE for the innodb_buffer_pool_size system variable based on innodb_page_size #3777

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MDEV-35889 set information_schema.system_variables NUMERIC_MIN_VALUE for the innodb_buffer_pool_size system variable based on innodb_page_size #3777

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5 changes: 3 additions & 2 deletions mysql-test/suite/innodb/t/restart.test
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Expand Up @@ -95,10 +95,11 @@ let $wait_condition =

--disable_cursor_protocol
SELECT @@innodb_buffer_pool_size INTO @innodb_buffer_pool_size_orig;
SELECT CEILING((256 + 64) * @@innodb_page_size / 1048576) * 1048576 INTO @min_pool_size;
SELECT CAST(NUMERIC_MIN_VALUE AS UNSIGNED) INTO @min_pool_size FROM information_schema.system_variables WHERE variable_name='INNODB_BUFFER_POOL_SIZE';
SET @out_of_bounds_pool_size=@min_pool_size - @@innodb_buffer_pool_chunk_size;
--enable_cursor_protocol
--error ER_WRONG_VALUE_FOR_VAR
EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@min_pool_size -1);
EXECUTE IMMEDIATE 'SET GLOBAL innodb_buffer_pool_size = ?' USING (@out_of_bounds_pool_size);

SHOW WARNINGS;

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3 changes: 3 additions & 0 deletions sql/set_var.cc
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Expand Up @@ -1117,6 +1117,9 @@ int fill_sysvars(THD *thd, TABLE_LIST *tables, COND *cond)

mysql_mutex_lock(&LOCK_global_system_variables);

if (var->cast_pluginvar())
plugin_opt_set_limits(&var->option, var->cast_mysql_sys_var());

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why do you need that?

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During plugin initialization the mysq_sys_var is copied to var->option giving the value of 2M for the variable:

Old value = 0
New value = 2097152
0x000000000090d6be in plugin_opt_set_limits (options=0x732ef70, opt=0x1f6ba90 <mysql_sysvar_buffer_pool_size>)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:3730
3730	    OPTION_SET_LIMITS(GET_ULL, options, (sysvar_ulonglong_t*) opt);
(rr) p options
$4 = (my_option *) 0x732ef70
(rr) p *options
$5 = {name = 0x732ef28 "innodb_buffer_pool_size", id = 0, 
  comment = 0x180465a "The size of the memory buffer InnoDB uses to cache data and indexes of its tables.", 
  value = 0x2132a58 <global_system_variables>, u_max_value = 0x0, typelib = 0x0, var_type = 8, arg_type = NO_ARG, def_value = 134217728, 
  min_value = 2097152, max_value = 0, sub_size = 0, block_size = 0, app_type = 0x732ef40}
(rr) bt
#0  0x000000000090d6be in plugin_opt_set_limits (options=0x732ef70, opt=0x1f6ba90 <mysql_sysvar_buffer_pool_size>)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:3730
#1  0x000000000090cc89 in sys_var_pluginvar::sys_var_pluginvar (this=0x732ef40, chain=0x7ffc59ce9360, 
    name_arg=0x732ef28 "innodb_buffer_pool_size", p=0x731fdc0, pv=0x1f6ba90 <mysql_sysvar_buffer_pool_size>, substitute=0x0)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:3486
#2  0x000000000091097a in test_plugin_options (tmp_root=0x7ffc59ce99a0, tmp=0x731fdc0, argc=0x2137bc8 <remaining_argc>, argv=0x72dac88)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:4244
#3  0x000000000090741b in plugin_initialize (tmp_root=0x7ffc59ce99a0, plugin=0x731fdc0, argc=0x2137bc8 <remaining_argc>, argv=0x72dac88, 
    options_only=false) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:1497
#4  0x0000000000906b9e in plugin_init (argc=0x2137bc8 <remaining_argc>, argv=0x72dac88, flags=0)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:1762
#5  0x000000000077fe63 in init_server_components () at /home/dan/repos/mariadb-server-10.5-quick/sql/mysqld.cc:4954
#6  0x000000000077c60c in mysqld_main (argc=9, argv=0x72dac88) at /home/dan/repos/mariadb-server-10.5-quick/sql/mysqld.cc:5562
#7  0x0000000000778bb2 in main (argc=8, argv=0x7ffc59ceb5a8) at /home/dan/repos/mariadb-server-10.5-quick/sql/main.cc:25
(rr) c
Continuing.

When InnoDB initializes, it changes it min_value because the innodb_page_size in this case is 64k.

Thread 1 hit Hardware watchpoint 1: -location mysql_sysvar_buffer_pool_size.min_val

Old value = 2097152
New value = 20971520
innodb_init_params () at /home/dan/repos/mariadb-server-10.5-quick/storage/innobase/handler/ha_innodb.cc:3551
3551		if (innobase_buffer_pool_size < MYSQL_SYSVAR_NAME(buffer_pool_size).min_val) {
(rr) bt
#0  innodb_init_params () at /home/dan/repos/mariadb-server-10.5-quick/storage/innobase/handler/ha_innodb.cc:3551
#1  0x00000000010d2368 in innodb_init (p=0x73ea3e8) at /home/dan/repos/mariadb-server-10.5-quick/storage/innobase/handler/ha_innodb.cc:4028
#2  0x0000000000c7af11 in ha_initialize_handlerton (plugin_=0x731fdc0) at /home/dan/repos/mariadb-server-10.5-quick/sql/handler.cc:648
#3  0x0000000000907b62 in plugin_do_initialize (plugin=0x731fdc0, state=@0x7ffc59ce93c8: 4)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:1453
#4  0x0000000000907481 in plugin_initialize (tmp_root=0x7ffc59ce99a0, plugin=0x731fdc0, argc=0x2137bc8 <remaining_argc>, argv=0x72dac88, 
    options_only=false) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:1507
#5  0x0000000000906b9e in plugin_init (argc=0x2137bc8 <remaining_argc>, argv=0x72dac88, flags=0)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:1762
#6  0x000000000077fe63 in init_server_components () at /home/dan/repos/mariadb-server-10.5-quick/sql/mysqld.cc:4954
#7  0x000000000077c60c in mysqld_main (argc=9, argv=0x72dac88) at /home/dan/repos/mariadb-server-10.5-quick/sql/mysqld.cc:5562
#8  0x0000000000778bb2 in main (argc=8, argv=0x7ffc59ceb5a8) at /home/dan/repos/mariadb-server-10.5-quick/sql/main.cc:25
(rr) c

Performing and information_schema select returns the original 2M value, despite the current situtation that the minimum is now 20M.

Continuing.
2025-01-28 16:18:35 0 [Note] InnoDB: innodb_page_size=65536
2025-01-28 16:18:35 0 [Note] InnoDB: !!!!!!!! UNIV_DEBUG switched on !!!!!!!!!
2025-01-28 16:18:35 0 [Note] InnoDB: Uses event mutexes
2025-01-28 16:18:35 0 [Note] InnoDB: Compressed tables use zlib 1.3.1.zlib-ng
2025-01-28 16:18:35 0 [Note] InnoDB: Number of pools: 1
2025-01-28 16:18:35 0 [Note] InnoDB: Using AVX512 instructions
2025-01-28 16:18:35 0 [Warning] InnoDB: Linux Native AIO disabled.
2025-01-28 16:18:35 0 [Note] InnoDB: Initializing buffer pool, total size = 134217728, chunk size = 134217728
2025-01-28 16:18:35 0 [Note] InnoDB: Completed initialization of buffer pool
2025-01-28 16:18:35 0 [Note] InnoDB: 128 rollback segments are active.
2025-01-28 16:18:35 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2025-01-28 16:18:35 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2025-01-28 16:18:35 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
2025-01-28 16:18:35 0 [Note] InnoDB: 10.5.28 started; log sequence number 45554; transaction id 20
2025-01-28 16:18:35 0 [Note] Plugin 'FEEDBACK' is disabled.
2025-01-28 16:18:35 0 [Note] InnoDB: Loading buffer pool(s) from /tmp/build-mariadb-server-10.5-quick-debug-datadir/ib_buffer_pool
2025-01-28 16:18:35 0 [Note] InnoDB: Buffer pool(s) load completed at 250128 16:18:35
2025-01-28 16:18:35 0 [Note] Reading of all Master_info entries succeeded
2025-01-28 16:18:35 0 [Note] Added new Master_info '' to hash table
2025-01-28 16:18:35 0 [Note] sql/mariadbd: ready for connections.
Version: '10.5.28-MariaDB-debug'  socket: '/tmp/build-mariadb-server-10.5-quick-debug.sock'  port: 0  Source distribution
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Thread 13 hit Breakpoint 3, sys_var_pluginvar::cast_pluginvar (this=0x732ef40) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:317
317	  sys_var_pluginvar *cast_pluginvar() override { return this; }
(rr) p option
$6 = {name = 0x732ef28 "innodb_buffer_pool_size", id = 0, 
  comment = 0x180465a "The size of the memory buffer InnoDB uses to cache data and indexes of its tables.", 
  value = 0x2132a58 <global_system_variables>, u_max_value = 0x0, typelib = 0x0, var_type = 8, arg_type = REQUIRED_ARG, def_value = 134217728, 
  min_value = 2097152, max_value = 9223372036854775807, sub_size = 0, block_size = 1048576, app_type = 0x732ef40}
(rr) bt
#0  sys_var_pluginvar::cast_pluginvar (this=0x732ef40) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:317
#1  0x000000000090c26f in find_sys_var (thd=0x7fbdec002258, str=0x7fbdec019fa8 "innodb_buffer_pool_size", length=23, throw_error=false)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_plugin.cc:2971
#2  0x0000000000d29135 in get_system_var (thd=0x7fbdec002258, var_type=SHOW_OPT_DEFAULT, name=0x7fbe177644b0, 
    component=0x18a8000 <null_clex_str>) at /home/dan/repos/mariadb-server-10.5-quick/sql/item_func.cc:6609
#3  0x00000000008bbe09 in LEX::make_item_sysvar (this=0x7fbdec006348, thd=0x7fbdec002258, type=SHOW_OPT_DEFAULT, name=0x7fbe177644b0, 
    component=0x18a8000 <null_clex_str>) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_lex.cc:7989
#4  0x0000000000beb7f2 in LEX::make_item_sysvar (this=0x7fbdec006348, thd=0x7fbdec002258, type=SHOW_OPT_DEFAULT, name=0x7fbe177644b0)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_lex.h:4218
#5  0x0000000000bd16a6 in MYSQLparse (thd=0x7fbdec002258) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_yacc.yy:11401
#6  0x00000000008fcbe3 in parse_sql (thd=0x7fbdec002258, parser_state=0x7fbe17765838, creation_ctx=0x0, do_pfs_digest=true)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_parse.cc:10683
#7  0x00000000008e3d5a in mysql_parse (thd=0x7fbdec002258, 
    rawbuf=0x7fbdec0198b0 "SELECT @@innodb_buffer_pool_size, @@innodb_page_size, information_schema.system_variables.NUMERIC_MIN_VALUE FROM information_schema.system_variables where information_schema.system_variables.variable_"..., length=230, parser_state=0x7fbe17765838, 
    is_com_multi=false, is_next_command=false) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_parse.cc:8203
#8  0x00000000008e06ed in dispatch_command (command=COM_QUERY, thd=0x7fbdec002258, 
    packet=0x7fbdec00e7b9 "SELECT @@innodb_buffer_pool_size, @@innodb_page_size, information_schema.system_variables.NUMERIC_MIN_VALUE FROM information_schema.system_variables where information_schema.system_variables.variable_"..., packet_length=230, is_com_multi=false, 
    is_next_command=false) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_parse.cc:1891
#9  0x00000000008e4dd3 in do_command (thd=0x7fbdec002258) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_parse.cc:1375
#10 0x0000000000a9e9f8 in do_handle_one_connection (connect=0x79946c8, put_in_cache=true)
    at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_connect.cc:1386
#11 0x0000000000a9e790 in handle_one_connection (arg=0x79946c8) at /home/dan/repos/mariadb-server-10.5-quick/sql/sql_connect.cc:1298
#12 0x0000000000fe30ec in pfs_spawn_thread (arg=0x78986c8) at /home/dan/repos/mariadb-server-10.5-quick/storage/perfschema/pfs.cc:2201
#13 0x00007fbe2c47d148 in start_thread () from /lib64/libc.so.6
#14 0x00007fbe2c500ed4 in clone () from /lib64/libc.so.6

At some point to make information_schema.sysvars correct we need to pull the new mysql_sysvar_buffer_pool_size.min_value into the options used by the information schema. As the innodb_buffer_pool_size is dynamic, it makes sense to have a value in the information_schema that reflects its current value.

// SESSION_VALUE
store_var(fields[1], var, OPT_SESSION, &strbuf);

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1 change: 1 addition & 0 deletions sql/set_var.h
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Expand Up @@ -111,6 +111,7 @@ class sys_var: protected Value_source // for double_from_string_with_check
of sys_var_pluginvar, and 0 otherwise.
*/
virtual sys_var_pluginvar *cast_pluginvar() { return 0; }
virtual const struct st_mysql_sys_var *cast_mysql_sys_var() const { return nullptr; }

bool check(THD *thd, set_var *var);
const uchar *value_ptr(THD *thd, enum_var_type type, const LEX_CSTRING *base) const;
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9 changes: 9 additions & 0 deletions sql/sql_plugin.cc
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Expand Up @@ -315,6 +315,7 @@ class sys_var_pluginvar: public sys_var, public Sql_alloc
st_plugin_int *p, st_mysql_sys_var *plugin_var_arg,
const char *substitute);
sys_var_pluginvar *cast_pluginvar() override { return this; }
virtual const struct st_mysql_sys_var *cast_mysql_sys_var() const override { return plugin_var; }
uchar* real_value_ptr(THD *thd, enum_var_type type) const;
TYPELIB* plugin_var_typelib(void) const;
const uchar* do_value_ptr(THD *thd, enum_var_type type, const LEX_CSTRING *base) const;
Expand Down Expand Up @@ -3683,14 +3684,22 @@ bool sys_var_pluginvar::global_update(THD *thd, set_var *var)

#define OPTION_SET_LIMITS(type, options, opt) \
options->var_type= type; \
assert((opt)->def_val >= (opt)->min_val); \
assert((opt)->def_val <= (opt)->max_val); \
options->def_value= (opt)->def_val; \
assert((opt)->min_val <= (opt)->max_val); \
options->min_value= (opt)->min_val; \
options->max_value= (opt)->max_val; \
assert((opt)->blk_sz == 0 || ((opt)->min_val % (opt)->blk_sz) == 0); \
assert((opt)->blk_sz == 0 || ((opt)->max_val % (opt)->blk_sz) == 0); \
options->block_size= (long) (opt)->blk_sz

#define OPTION_SET_LIMITS_DOUBLE(options, opt) \
options->var_type= GET_DOUBLE; \
assert((opt)->def_val >= (opt)->min_val); \
assert((opt)->def_val <= (opt)->max_val); \
options->def_value= (longlong) getopt_double2ulonglong((opt)->def_val); \
assert((opt)->min_val <= (opt)->max_val); \
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it's the server code, you could use DBUG_ASSERT here, as far as I can see

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Note, might need to drop the max divisible by block size - myisam_max_sort_file_size fails this as would other with a max value divisible by a power of two value.

(gdb) p *(sysvar_ulonglong_t*) opt
$4 = {flags = 132, name = 0x1793cda "max_sort_file_size", 
  comment = 0x187e40a "Don't use the fast sort index method to created index if the temporary file would get bigger than this", check = 0x9129c0 <check_func_longlong(THD*, st_mysql_sys_var*, void*, st_mysql_value*)>, 
  update = 0x912b80 <update_func_longlong(THD*, st_mysql_sys_var*, void*, void const*)>, 
  value = 0x1f78888 <myisam_max_temp_length>, def_val = 9223372036853727232, min_val = 0, 
  max_val = 9223372036854775807, blk_sz = 1048576}
(gdb) p (((sysvar_ulonglong_t*) opt)->max_val % ((sysvar_ulonglong_t*) opt)->blk_sz)
$5 = 1048575
(gdb) p 9223372036854775807 % 1048576
$6 = 1048575
(gdb) p 9223372036854775808 % 1048576
$7 = 0

options->min_value= (longlong) getopt_double2ulonglong((opt)->min_val); \
options->max_value= getopt_double2ulonglong((opt)->max_val); \
options->block_size= (long) (opt)->blk_sz;
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