text: execute java org.activiti.engine.impl.db.upgrade.DbUpgradeStep52To53InsertPropertyHistoryLevel
  
  -- removing not null constraint from ACT_HI_DETAIL.PROC_INST_ID_ and ACT_HI_DETAIL.EXECUTION_ID_
  
  create table ACT_HI_DETAIL_TMP (
      ID_ NVARCHAR2(64) not null,
      TYPE_ NVARCHAR2(255) not null,
      PROC_INST_ID_ NVARCHAR2(64),
      EXECUTION_ID_ NVARCHAR2(64),
      TASK_ID_ NVARCHAR2(64),
      ACT_INST_ID_ NVARCHAR2(64),
      NAME_ NVARCHAR2(255),
      VAR_TYPE_ NVARCHAR2(64),
      REV_ INTEGER,
      TIME_ TIMESTAMP(6) not null,
      BYTEARRAY_ID_ NVARCHAR2(64),
      DOUBLE_ NUMBER(*,10),
      LONG_ NUMBER(19,0),
      TEXT_ NVARCHAR2(255),
      TEXT2_ NVARCHAR2(255),
      primary key (ID_)
  );
  
  insert into ACT_HI_DETAIL_TMP (ID_,TYPE_,PROC_INST_ID_,EXECUTION_ID_,TASK_ID_,ACT_INST_ID_,NAME_,VAR_TYPE_,REV_,TIME_,BYTEARRAY_ID_,DOUBLE_,LONG_,TEXT_,TEXT2_)
  select ID_,TYPE_,PROC_INST_ID_,EXECUTION_ID_,TASK_ID_,ACT_INST_ID_,NAME_,VAR_TYPE_,REV_,TIME_,BYTEARRAY_ID_,DOUBLE_,LONG_,TEXT_,TEXT2_ from ACT_HI_DETAIL;
  
  drop table ACT_HI_DETAIL;
  
  create table ACT_HI_DETAIL (
      ID_ NVARCHAR2(64) not null,
      TYPE_ NVARCHAR2(255) not null,
      PROC_INST_ID_ NVARCHAR2(64),
      EXECUTION_ID_ NVARCHAR2(64),
      TASK_ID_ NVARCHAR2(64),
      ACT_INST_ID_ NVARCHAR2(64),
      NAME_ NVARCHAR2(255),
      VAR_TYPE_ NVARCHAR2(64),
      REV_ INTEGER,
      TIME_ TIMESTAMP(6) not null,
      BYTEARRAY_ID_ NVARCHAR2(64),
      DOUBLE_ NUMBER(*,10),
      LONG_ NUMBER(19,0),
      TEXT_ NVARCHAR2(255),
      TEXT2_ NVARCHAR2(255),
      primary key (ID_)
  );
  
  create index ACT_IDX_HI_DETAIL_PROC_INST on ACT_HI_DETAIL(PROC_INST_ID_);
  create index ACT_IDX_HI_DETAIL_ACT_INST on ACT_HI_DETAIL(ACT_INST_ID_);
  create index ACT_IDX_HI_DETAIL_TIME on ACT_HI_DETAIL(TIME_);
  create index ACT_IDX_HI_DETAIL_NAME on ACT_HI_DETAIL(NAME_);
  
  insert into ACT_HI_DETAIL (ID_,TYPE_,PROC_INST_ID_,EXECUTION_ID_,TASK_ID_,ACT_INST_ID_,NAME_,VAR_TYPE_,REV_,TIME_,BYTEARRAY_ID_,DOUBLE_,LONG_,TEXT_,TEXT2_)
  select ID_,TYPE_,PROC_INST_ID_,EXECUTION_ID_,TASK_ID_,ACT_INST_ID_,NAME_,VAR_TYPE_,REV_,TIME_,BYTEARRAY_ID_,DOUBLE_,LONG_,TEXT_,TEXT2_ from ACT_HI_DETAIL_TMP;
  
  drop table ACT_HI_DETAIL_TMP;
  
  -- Add column PRIORITY_ to ACT_HI_TASKINST and set to default priority (ACT-484)
  alter table ACT_HI_TASKINST add PRIORITY_ INTEGER;
  update ACT_HI_TASKINST set PRIORITY_ = 50;