MDEV-29225 make explicit_defaults_for_timestamps SESSION variable

make @@explicit_defaults_for_timestamp session variable

mysql-test/main/type_timestamp.result

@@ -1322,3 +1322,27 @@ SET timestamp=DEFAULT;
 #
 # End of 10.4 tests
 #
+#
+# MDEV-29225 make explicit_defaults_for_timestamps SESSION variable
+#
+set explicit_defaults_for_timestamp=OFF;
+create table t1 (f1 timestamp, f2 timestamp);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f1` timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp(),
+  `f2` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00'
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
+set explicit_defaults_for_timestamp=ON;
+create table t1 (f1 timestamp, f2 timestamp);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f1` timestamp NULL DEFAULT NULL,
+  `f2` timestamp NULL DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
+#
+# End of 10.10 tests
+#

mysql-test/main/type_timestamp.test

@@ -874,7 +874,23 @@ SELECT CASE WHEN a THEN DEFAULT(a) END FROM t1;
 DROP TABLE t1;
 SET timestamp=DEFAULT;
 
-
 --echo #
 --echo # End of 10.4 tests
 --echo #
+
+--echo #
+--echo # MDEV-29225 make explicit_defaults_for_timestamps SESSION variable
+--echo #
+
+set explicit_defaults_for_timestamp=OFF;
+create table t1 (f1 timestamp, f2 timestamp);
+show create table t1;
+drop table t1;
+set explicit_defaults_for_timestamp=ON;
+create table t1 (f1 timestamp, f2 timestamp);
+show create table t1;
+drop table t1;
+
+--echo #
+--echo # End of 10.10 tests
+--echo #

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

@@ -1,21 +0,0 @@
-select @@global.explicit_defaults_for_timestamp;
-@@global.explicit_defaults_for_timestamp
-0
-select @@session.explicit_defaults_for_timestamp;
-ERROR HY000: Variable 'explicit_defaults_for_timestamp' is a GLOBAL variable
-show global variables like 'explicit_defaults_for_timestamp';
-Variable_name	Value
-explicit_defaults_for_timestamp	OFF
-show session variables like 'explicit_defaults_for_timestamp';
-Variable_name	Value
-explicit_defaults_for_timestamp	OFF
-select * from information_schema.global_variables where variable_name='explicit_defaults_for_timestamp';
-VARIABLE_NAME	VARIABLE_VALUE
-EXPLICIT_DEFAULTS_FOR_TIMESTAMP	OFF
-select * from information_schema.session_variables where variable_name='explicit_defaults_for_timestamp';
-VARIABLE_NAME	VARIABLE_VALUE
-EXPLICIT_DEFAULTS_FOR_TIMESTAMP	OFF
-set global explicit_defaults_for_timestamp=true;
-ERROR HY000: Variable 'explicit_defaults_for_timestamp' is a read only variable
-set session explicit_defaults_for_timestamp=true;
-ERROR HY000: Variable 'explicit_defaults_for_timestamp' is a read only variable

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

@@ -1,3 +1,4 @@
+set @@explicit_defaults_for_timestamp=0;
 CREATE TABLE t1 (a TIMESTAMP);
 SHOW CREATE TABLE t1;
 Table	Create Table

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

@@ -1,3 +1,4 @@
+set @@explicit_defaults_for_timestamp=1;
 CREATE TABLE t1 (a TIMESTAMP);
 SHOW CREATE TABLE t1;
 Table	Create Table

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

@@ -913,14 +913,14 @@ ENUM_VALUE_LIST	NULL
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	EXPLICIT_DEFAULTS_FOR_TIMESTAMP
-VARIABLE_SCOPE	GLOBAL
+VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	BOOLEAN
 VARIABLE_COMMENT	This option causes CREATE TABLE to create all TIMESTAMP columns as NULL with DEFAULT NULL attribute, Without this option, TIMESTAMP columns are NOT NULL and have implicit DEFAULT clauses.
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	OFF,ON
-READ_ONLY	YES
+READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	EXTERNAL_USER
 VARIABLE_SCOPE	SESSION ONLY

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

@@ -933,14 +933,14 @@ ENUM_VALUE_LIST	NULL
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	EXPLICIT_DEFAULTS_FOR_TIMESTAMP
-VARIABLE_SCOPE	GLOBAL
+VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	BOOLEAN
 VARIABLE_COMMENT	This option causes CREATE TABLE to create all TIMESTAMP columns as NULL with DEFAULT NULL attribute, Without this option, TIMESTAMP columns are NOT NULL and have implicit DEFAULT clauses.
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	OFF,ON
-READ_ONLY	YES
+READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	EXTERNAL_USER
 VARIABLE_SCOPE	SESSION ONLY

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

@@ -1,26 +0,0 @@
-#
-# show the global and session values;
-#
-select @@global.explicit_defaults_for_timestamp;
-
-#
-# Test that it's a global-only variable
-#
---error ER_INCORRECT_GLOBAL_LOCAL_VAR
-select @@session.explicit_defaults_for_timestamp;
-
-show global variables like 'explicit_defaults_for_timestamp';
-show session variables like 'explicit_defaults_for_timestamp';
-
---disable_warnings
-select * from information_schema.global_variables where variable_name='explicit_defaults_for_timestamp';
-select * from information_schema.session_variables where variable_name='explicit_defaults_for_timestamp';
---enable_warnings
-
-#
-# show that it's read-only
-#
---error ER_INCORRECT_GLOBAL_LOCAL_VAR
-set global explicit_defaults_for_timestamp=true;
---error ER_INCORRECT_GLOBAL_LOCAL_VAR
-set session explicit_defaults_for_timestamp=true;

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

@@ -1,8 +1,3 @@
---disable_query_log
+set @@explicit_defaults_for_timestamp=0;
-if (`SELECT @@explicit_defaults_for_timestamp`)
-{
-  Skip Need explicit-defaults-for-timestamp=off;
-}
---enable_query_log
 
 --source inc/explicit_defaults_for_timestamp.inc

mysql-test/suite/sys_vars/t/explicit_defaults_for_timestamp_on-master.opt

@@ -1 +0,0 @@
---explicit-defaults-for-timestamp=on

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

@@ -1,8 +1,3 @@
---disable_query_log
+set @@explicit_defaults_for_timestamp=1;
-if (!`SELECT @@explicit_defaults_for_timestamp`)
-{
-  Skip Need explicit-defaults-for-timestamp=on;
-}
---enable_query_log
 
 --source inc/explicit_defaults_for_timestamp.inc

sql/field.cc

@@ -10666,7 +10666,7 @@ bool Column_definition::check(THD *thd)
       TIMESTAMP columns get implicit DEFAULT value when
       explicit_defaults_for_timestamp is not set.
     */
-    if ((opt_explicit_defaults_for_timestamp ||
+    if (((thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP) ||
         !is_timestamp_type()) && !vers_sys_field())
     {
       flags|= NO_DEFAULT_VALUE_FLAG;

sql/mysqld.cc

@@ -391,7 +391,6 @@ my_bool opt_show_slave_auth_info;
 my_bool opt_log_slave_updates= 0;
 my_bool opt_replicate_annotate_row_events= 0;
 my_bool opt_mysql56_temporal_format=0, strict_password_validation= 1;
-my_bool opt_explicit_defaults_for_timestamp= 0;
 char *opt_slave_skip_errors;
 char *opt_slave_transaction_retry_errors;
 

sql/mysqld.h

@@ -948,7 +948,6 @@ extern my_bool opt_stack_trace, disable_log_notes;
 extern my_bool opt_expect_abort;
 extern my_bool opt_slave_sql_verify_checksum;
 extern my_bool opt_mysql56_temporal_format, strict_password_validation;
-extern my_bool opt_explicit_defaults_for_timestamp;
 extern ulong binlog_checksum_options;
 extern bool max_user_connections_checking;
 extern ulong opt_binlog_dbug_fsync_sleep;

sql/sql_insert.cc

@@ -4432,7 +4432,7 @@ TABLE *select_create::create_table_from_items(THD *thd, List<Item> *items,
   tmp_table.maybe_null= 0;
   tmp_table.in_use= thd;
 
-  if (!opt_explicit_defaults_for_timestamp)
+  if (!(thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP))
     promote_first_timestamp_column(&alter_info->create_list);
 
   if (create_info->fix_create_fields(thd, alter_info, *create_table))

sql/sql_priv.h

@@ -136,8 +136,7 @@
 #define OPTION_QUICK            (1ULL << 22)    // SELECT (for DELETE)
 #define OPTION_KEEP_LOG         (1ULL << 23)    // THD, user
 
-/* The following is used to detect a conflict with DISTINCT */
+#define OPTION_EXPLICIT_DEF_TIMESTAMP   (1ULL << 24) // THD, user
-#define SELECT_ALL              (1ULL << 24)    // SELECT, user, parser
 #define OPTION_GTID_BEGIN       (1ULL << 25)    // GTID BEGIN found in log
 
 /** The following can be set when importing tables in a 'wrong order'
@@ -180,10 +179,11 @@
 #define OPTION_NO_QUERY_CACHE           (1ULL << 39) // SELECT, user
 #define OPTION_PROCEDURE_CLAUSE         (1ULL << 40) // Internal usage
 #define SELECT_NO_UNLOCK                (1ULL << 41) // SELECT, intern
-#define SELECT_NO_UNLOCK                (1ULL << 41) // SELECT, intern
 #define OPTION_BIN_TMP_LOG_OFF          (1ULL << 42) // disable binlog, intern
 /* Disable commit of binlog. Used to combine many DDL's and DML's as one */
 #define OPTION_BIN_COMMIT_OFF           (1ULL << 43)
+/* The following is used to detect a conflict with DISTINCT */
+#define SELECT_ALL              (1ULL << 44)    // SELECT, user, parser
 
 #define OPTION_LEX_FOUND_COMMENT        (1ULL << 0) //  intern, parser
 

sql/sql_table.cc

@@ -4478,7 +4478,7 @@ without_overlaps_err:
         !sql_field->has_default_function() &&
         (sql_field->flags & NOT_NULL_FLAG) &&
         (!sql_field->is_timestamp_type() ||
-         opt_explicit_defaults_for_timestamp)&&
+         (thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP))&&
         !sql_field->vers_sys_field())
     {
       sql_field->flags|= NO_DEFAULT_VALUE_FLAG;
@@ -4489,7 +4489,7 @@ without_overlaps_err:
         !sql_field->default_value && !sql_field->vcol_info &&
         !sql_field->vers_sys_field() &&
         sql_field->is_timestamp_type() &&
-        !opt_explicit_defaults_for_timestamp &&
+        !(thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP) &&
         (sql_field->flags & NOT_NULL_FLAG) &&
         (type == Field::NONE || type == Field::TIMESTAMP_UN_FIELD))
     {
@@ -5592,7 +5592,7 @@ bool mysql_create_table(THD *thd, TABLE_LIST *create_table,
   else
     create_table_mode= C_ASSISTED_DISCOVERY;
 
-  if (!opt_explicit_defaults_for_timestamp)
+  if (!(thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP))
     promote_first_timestamp_column(&alter_info->create_list);
 
   /* We can abort create table for any table type */
@@ -10511,7 +10511,7 @@ do_continue:;
       create_info->fix_period_fields(thd, alter_info))
     DBUG_RETURN(true);
 
-  if (!opt_explicit_defaults_for_timestamp)
+  if (!(thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP))
     promote_first_timestamp_column(&alter_info->create_list);
 
 #ifdef WITH_PARTITION_STORAGE_ENGINE

sql/sql_type.cc

@@ -4271,7 +4271,7 @@ Column_definition_set_attributes(THD *thd,
                                  column_definition_type_t type) const
 {
   Type_handler::Column_definition_set_attributes(thd, def, attr, cs, type);
-  if (!opt_explicit_defaults_for_timestamp)
+  if (!(thd->variables.option_bits & OPTION_EXPLICIT_DEF_TIMESTAMP))
     def->flags|= NOT_NULL_FLAG;
   return false;
 }

sql/sys_vars.cc

@@ -719,15 +719,13 @@ Sys_binlog_direct(
        CMD_LINE(OPT_ARG), DEFAULT(FALSE),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(binlog_direct_check));
 
-
+static Sys_var_bit Sys_explicit_defaults_for_timestamp(
-static Sys_var_mybool Sys_explicit_defaults_for_timestamp(
        "explicit_defaults_for_timestamp",
        "This option causes CREATE TABLE to create all TIMESTAMP columns "
        "as NULL with DEFAULT NULL attribute, Without this option, "
        "TIMESTAMP columns are NOT NULL and have implicit DEFAULT clauses.",
-       READ_ONLY GLOBAL_VAR(opt_explicit_defaults_for_timestamp),
+       SESSION_VAR(option_bits), CMD_LINE(OPT_ARG),
-       CMD_LINE(OPT_ARG), DEFAULT(FALSE));
+       OPTION_EXPLICIT_DEF_TIMESTAMP, DEFAULT(FALSE));
-
 
 static Sys_var_ulonglong Sys_bulk_insert_buff_size(
        "bulk_insert_buffer_size", "Size of tree cache used in bulk "