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Find out if two rows came from same transaction in Oracle

Submitted by: @import:stackexchange-dba··
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rowssamecameoracletwotransactionfindfromout

Problem

I am using Oracle 11.1 and would like to figure out if two rows in one table where inserted by the same transaction.

Is there an easy sql statement to map a row to an transactions id? The table is an insert only table.

What are my options? Some baisc solution would do, I don't really want some extra tool to analyze the log files.

Thanks

Solution

You can get the SCN for a row with the ORA_ROWSCN pseudocolumn

Unless you have set row-level dependency tracking for the table, this will report the SCN of the last change to the block the row is in, which may not be much use. You can turn on row-level dependency tracking at create table time only, so you may need to drop and re-create your table.

Note that row-level tracking increases the size of each row by 6 bytes.

-
with rowdependencies:

create table foo rowdependencies as
select level as id from dual connect by level<=10000;

select count(distinct ora_rowscn) from foo;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
1                         

begin
  for r in (select id from foo) loop
    update foo set id = id where id=r.id;
    commit;
  end loop;
end;
/

select count(distinct ora_rowscn) from foo;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
10000


-
without rowdependencies (norowdependencies is the default):

create table bar as
select level as id from dual connect by level<=10000;

select count(distinct ora_rowscn) from bar;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
1                         

begin
  for r in (select id from bar) loop
    update bar set id = id where id=r.id;
    commit;
  end loop;
end;
/

select count(distinct ora_rowscn) from bar;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
16

Code Snippets

create table foo rowdependencies as
select level as id from dual connect by level<=10000;

select count(distinct ora_rowscn) from foo;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
1                         

begin
  for r in (select id from foo) loop
    update foo set id = id where id=r.id;
    commit;
  end loop;
end;
/

select count(distinct ora_rowscn) from foo;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
10000
create table bar as
select level as id from dual connect by level<=10000;

select count(distinct ora_rowscn) from bar;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
1                         

begin
  for r in (select id from bar) loop
    update bar set id = id where id=r.id;
    commit;
  end loop;
end;
/

select count(distinct ora_rowscn) from bar;

COUNT(DISTINCTORA_ROWSCN) 
------------------------- 
16

Context

StackExchange Database Administrators Q#8418, answer score: 8

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