Oracle reset sequence generator (non rebuild)

1、 background

1.1 background

There are 5 A sequence generator （ Respectively ：seq1、seq2、seq3、seq4、seq5）, The function of each sequence is to produce [10000,19999)、[20000,29999)、[30000,39999)、[40000,49999)、[50000,59999) The numerical . Create a sequence of DDL as follows ：

 

CREATE SEQUENCE seq1
  START WITH 10001
  MAXVALUE 19999
  MINVALUE 10001
  increment by 1
  NOCYCLE
  NOCACHE
  ORDER;

The others are the same , The difference is just the starting value

 

1.2 problem

Now every night 00:00 There's a timed mission , The function is to delete the sequence generator , Then rebuild , Ensure that the daily sequence generator starts from the starting value .

There have been occasional problems recently , Inquiry , Reset the timing task of the sequence generator at run time , There are other scheduled tasks using these sequence generators , This causes the scheduled task to fail .

therefore , Site requirements ： It is necessary to reset the sequence generator , And avoid the occurrence of exceptions .

therefore , Reset the sequence generator in a non reconstruction way

2、 Solution

establish procedure, as follows ：

 

/*
   founder ： Zheng Lin  2017-8-30
   Method statement ： Reset the sequence generator 
   Parameter description ：v_seqname Sequence generator name ;v_max_value The maximum value of the sequence 
   Other instructions ：cache Process by default 
*/
create or replace procedure seq_reset(v_seqname varchar2,v_max_value number) as
  n    number(10);
  tsql varchar2(100);
  begin
		
	   --1、 Set to nocahe（ Prevent emergence ora-04013 error ）
	   execute immediate 'alter sequence '|| v_seqname ||' NOCACHE';
		
       --2、 Get the current value of the sequence 
       execute immediate 'select '|| v_seqname ||'.nextval from dual' into n;
       n :=v_max_value-n;
       --3、 Change step size 
       tsql := 'alter sequence '|| v_seqname ||' increment by ' || n;
       execute immediate tsql;
       
       --4、 Get current value 
       begin
               execute immediate 'select '|| v_seqname ||'.nextval from dual' into n;
       exception                
               when others then
                 if sqlcode='-8004' then
                    tsql:='alter sequence '||v_seqname||' increment by 1';
                    execute immediate tsql;
                 end if;
       end; 
       
       --5、 Recovery step 
       tsql := 'alter sequence ' || v_seqname ||' increment by 1';
       execute immediate tsql;
	   
	   --6、 recovery cache
	   execute immediate 'alter sequence '|| v_seqname ||' CACHE 20';
  
end seq_reset;

Parameters in ：v_seqname Is the name of the sequence generator ;v_max_value Is the maximum value of the sequence generator

 

such , Rewrite scheduled tasks , Can solve the current problem

 

SQL> set serveroutput on;
SQL> exec seq_reset('SRXS001',19999);
PL/SQL procedure successfully completed

 

 

3、 Reference material

1、 dynamic SQL, Reference resources ： dynamic SQL The data link

2、 Non reconstruction methods , Reference resources ： Non reconstituted Links

4、C# call procedure

        // Get the set data 
        private int executeProcedure()
        {
            int result = 1;
            // Get database connection 
            OracleConnection conn = DataBaseContext.GetSequenceOracleConnection();
            OracleCommand command = new OracleCommand();

            try
            {
                command.Connection = conn;
                command.CommandType = CommandType.StoredProcedure;

                List<SeqModel> seqList = getSeqList();
                // Complete execution procedure Methods 
                seqList.ForEach(t =>
                {
                    result = result * executeProcedure(t.SeqName, t.MaxValue, command);
                });

                conn.Close();

                return result;
            }
            catch (System.Exception ex)
            {
                SysLog.LogWrite("pharmacy.log", ex);
                return -1;
            }
            finally
            {
                if (conn != null) conn.Close();
            }
        }

        // perform procedure Methods 
        private int executeProcedure(string sequence_name, int max_value,OracleCommand command)
        {
            int execute_result = 0;
            try
            {
                command.CommandText = "seq_reset";
                command.Parameters.Clear();
                command.Parameters.Add("v_seqname", OracleDbType.Varchar2).Direction = ParameterDirection.Input;
                command.Parameters["v_seqname"].Value = sequence_name;
                command.Parameters.Add("v_max_value", OracleDbType.Int32).Direction = ParameterDirection.Input;
                command.Parameters["v_max_value"].Value = max_value;

                execute_result = command.ExecuteNonQuery();

                return execute_result;
            }
            catch (System.Exception ex)
            {
                SysLog.LogWrite("pharmacy.log", ex);
                return -1;
            }
        }