From d72462a29b434da87f66625d743bd8c7c0527876 Mon Sep 17 00:00:00 2001
From: Eugene Kosov <claprix@yandex.ru>
Date: Wed, 27 Dec 2017 16:41:43 +0300
Subject: [PATCH] SQL: TRX_ID to TIMESTAMP versioning switch [fixes #428]

---
 mysql-test/suite/versioning/r/trx_id.result | 12 ++++++
 mysql-test/suite/versioning/t/trx_id.test   | 11 +++++
 sql/handler.cc                              | 47 +++++++++------------
 3 files changed, 44 insertions(+), 26 deletions(-)

diff --git a/mysql-test/suite/versioning/r/trx_id.result b/mysql-test/suite/versioning/r/trx_id.result
index 7ab05d7ea4a..026acbd081c 100644
--- a/mysql-test/suite/versioning/r/trx_id.result
+++ b/mysql-test/suite/versioning/r/trx_id.result
@@ -79,6 +79,18 @@ algorithm=copy;
 select check_result(count(*) = @tmp) from mysql.transaction_registry;
 check_result(count(*) = @tmp)
 [CORRECT]
+# TRX_ID to TIMESTAMP versioning switch
+create or replace table t1 (
+x int,
+sys_start bigint unsigned as row start invisible,
+sys_end bigint unsigned as row end invisible,
+period for system_time (sys_start, sys_end)
+) engine innodb with system versioning;
+insert into t1 values (1);
+alter table t1 drop column sys_start, drop column sys_end;
+select sys_end = 18446744073709551615 as transaction_based from t1 for system_time all;
+transaction_based
+1
 drop table t1;
 set global system_versioning_transaction_registry=off;
 drop function check_result;
diff --git a/mysql-test/suite/versioning/t/trx_id.test b/mysql-test/suite/versioning/t/trx_id.test
index 1c201416026..d42333d56d9 100644
--- a/mysql-test/suite/versioning/t/trx_id.test
+++ b/mysql-test/suite/versioning/t/trx_id.test
@@ -81,6 +81,17 @@ alter table t1
 select check_result(count(*) = @tmp) from mysql.transaction_registry;
 
 
+--echo # TRX_ID to TIMESTAMP versioning switch
+create or replace table t1 (
+  x int,
+  sys_start bigint unsigned as row start invisible,
+  sys_end bigint unsigned as row end invisible,
+  period for system_time (sys_start, sys_end)
+) engine innodb with system versioning;
+insert into t1 values (1);
+alter table t1 drop column sys_start, drop column sys_end;
+select sys_end = 18446744073709551615 as transaction_based from t1 for system_time all;
+
 drop table t1;
 set global system_versioning_transaction_registry=off;
 drop function check_result;
diff --git a/sql/handler.cc b/sql/handler.cc
index 28f581d8b59..5cbcd936216 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -6852,8 +6852,7 @@ bool Vers_parse_info::is_end(const Create_field &f) const
   return f.flags & VERS_SYS_END_FLAG;
 }
 
-static Create_field *vers_init_sys_field(THD *thd, const char *field_name,
-                                         int flags)
+static Create_field *vers_init_sys_field(THD *thd, const char *field_name, int flags, bool integer)
 {
   Create_field *f= new (thd->mem_root) Create_field();
   if (!f)
@@ -6864,8 +6863,17 @@ static Create_field *vers_init_sys_field(THD *thd, const char *field_name,
   f->field_name.length= strlen(field_name);
   f->charset= system_charset_info;
   f->flags= flags;
-  f->set_handler(&type_handler_timestamp2);
-  f->length= MAX_DATETIME_PRECISION;
+  if (integer)
+  {
+    f->set_handler(&type_handler_longlong);
+    f->length= MY_INT64_NUM_DECIMAL_DIGITS - 1;
+    f->flags|= UNSIGNED_FLAG;
+  }
+  else
+  {
+    f->set_handler(&type_handler_timestamp2);
+    f->length= MAX_DATETIME_PRECISION;
+  }
   f->invisible= INVISIBLE_SYSTEM;
 
   if (f->check(thd))
@@ -6877,7 +6885,7 @@ static Create_field *vers_init_sys_field(THD *thd, const char *field_name,
 static bool vers_create_sys_field(THD *thd, const char *field_name,
                                   Alter_info *alter_info, int flags)
 {
-  Create_field *f= vers_init_sys_field(thd, field_name, flags);
+  Create_field *f= vers_init_sys_field(thd, field_name, flags, false);
   if (!f)
     return true;
 
@@ -6887,23 +6895,6 @@ static bool vers_create_sys_field(THD *thd, const char *field_name,
   return false;
 }
 
-static bool vers_change_sys_field(THD *thd, const char *field_name,
-                                  Alter_info *alter_info, int flags,
-                                  const char *change)
-{
-  Create_field *f= vers_init_sys_field(thd, field_name, flags);
-  if (!f)
-    return true;
-
-  f->change.str= change;
-  f->change.length= strlen(change);
-
-  alter_info->flags|= Alter_info::ALTER_CHANGE_COLUMN;
-  alter_info->create_list.push_back(f);
-
-  return false;
-}
-
 const LString Vers_parse_info::default_start= "sys_trx_start";
 const LString Vers_parse_info::default_end= "sys_trx_end";
 
@@ -7330,11 +7321,15 @@ bool Vers_parse_info::fix_alter_info(THD *thd, Alter_info *alter_info,
           return true;
         }
 
-        if (vers_change_sys_field(thd, name, alter_info,
-                                  f->flags & VERS_SYSTEM_FIELD, name))
-        {
+        bool integer= table->vers_start_field()->type() == MYSQL_TYPE_LONGLONG;
+        Create_field *field= vers_init_sys_field(thd, name, f->flags & VERS_SYSTEM_FIELD, integer);
+        if (!field)
           return true;
-        }
+
+        field->change= f->field_name;
+
+        alter_info->flags|= Alter_info::ALTER_CHANGE_COLUMN;
+        alter_info->create_list.push_back(field);
 
         it.remove();