MDEV-17475: Increase maximum possible value for table_definition_cache to match table_open_cache

Allow table definition cache be bigger than open table cache (due to problem with VIEWs and prepared statements).

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

@@ -28,14 +28,14 @@ Warning	1292	Truncated incorrect table_definition_cache value: '2'
 SELECT @@global.table_definition_cache;
 @@global.table_definition_cache
 400
-SET @@global.table_definition_cache = 524287;
+SET @@global.table_definition_cache = 2097151;
 SELECT @@global.table_definition_cache;
 @@global.table_definition_cache
-524287
-SET @@global.table_definition_cache = 524288;
+2097151
+SET @@global.table_definition_cache = 2097152;
 SELECT @@global.table_definition_cache;
 @@global.table_definition_cache
-524288
+2097152
 '#--------------------FN_DYNVARS_019_04-------------------------#'
 SET @@global.table_definition_cache = 0;
 Warnings:
@@ -49,18 +49,18 @@ Warning	1292	Truncated incorrect table_definition_cache value: '-1024'
 SELECT @@global.table_definition_cache;
 @@global.table_definition_cache
 400
-SET @@global.table_definition_cache = 524289;
+SET @@global.table_definition_cache = 2097153;
 Warnings:
-Warning	1292	Truncated incorrect table_definition_cache value: '524289'
+Warning	1292	Truncated incorrect table_definition_cache value: '2097153'
 SELECT @@global.table_definition_cache;
 @@global.table_definition_cache
-524288
+2097152
 SET @@global.table_definition_cache = 42949672950;
 Warnings:
 Warning	1292	Truncated incorrect table_definition_cache value: '42949672950'
 SELECT @@global.table_definition_cache;
 @@global.table_definition_cache
-524288
+2097152
 SET @@global.table_definition_cache = 21221204.10;
 ERROR 42000: Incorrect argument type to variable 'table_definition_cache'
 SET @@global.table_definition_cache = ON;

mysql-test/suite/sys_vars/t/table_definition_cache_basic.test

@@ -64,9 +64,9 @@ SET @@global.table_definition_cache = 1;
 SELECT @@global.table_definition_cache;
 SET @@global.table_definition_cache = 2;
 SELECT @@global.table_definition_cache;
-SET @@global.table_definition_cache = 524287;
+SET @@global.table_definition_cache = 2097151;
 SELECT @@global.table_definition_cache;
-SET @@global.table_definition_cache = 524288;
+SET @@global.table_definition_cache = 2097152;
 SELECT @@global.table_definition_cache;
 
 
@@ -79,7 +79,7 @@ SET @@global.table_definition_cache = 0;
 SELECT @@global.table_definition_cache;
 SET @@global.table_definition_cache = -1024;
 SELECT @@global.table_definition_cache;
-SET @@global.table_definition_cache = 524289;
+SET @@global.table_definition_cache = 2097153;
 SELECT @@global.table_definition_cache;
 SET @@global.table_definition_cache = 42949672950;
 SELECT @@global.table_definition_cache;

sql/sys_vars.cc

@@ -3039,11 +3039,15 @@ static Sys_var_charptr Sys_system_time_zone(
        NO_CMD_LINE,
        IN_SYSTEM_CHARSET, DEFAULT(system_time_zone));
 
+/*
+  If One use views with prepared statements this should be bigger than
+  table_open_cache (now we allow 2 times bigger value)
+*/
 static Sys_var_ulong Sys_table_def_size(
        "table_definition_cache",
        "The number of cached table definitions",
        GLOBAL_VAR(tdc_size), CMD_LINE(REQUIRED_ARG),
-       VALID_RANGE(TABLE_DEF_CACHE_MIN, 512*1024),
+       VALID_RANGE(TABLE_DEF_CACHE_MIN, 2*1024*1024),
        DEFAULT(TABLE_DEF_CACHE_DEFAULT), BLOCK_SIZE(1));
 
 
@@ -3055,7 +3059,7 @@ static bool fix_table_open_cache(sys_var *, THD *, enum_var_type)
   return false;
 }
 
-
+/* Check the table_definition_cache comment if makes changes */
 static Sys_var_ulong Sys_table_cache_size(
        "table_open_cache", "The number of cached open tables",
        GLOBAL_VAR(tc_size), CMD_LINE(REQUIRED_ARG),