Oracle Query跟踪特定日期的表更改

Question

我有以下查询，它为我提供了表中最后一次DML操作发生的时间，我想对其进行一些修改以跟踪整天，以便无论特定表的上下文发生了什么变化，我都可以获得完整的历史记录当天，所以请让我知道如何在查询下方修改此内容

SELECT SCN_TO_TIMESTAMP(MAX(ORA_ROWSCN)) from mytablename;

Answer 1

There is a companion to scn_to_timestamp which gives you the SCN for a given time; so to see rows whose ora_rowscn is today you could do:

select * from table_a where ora_rowscn >= timestamp_to_scn(trunc(sysdate));

There are a few caveats though, of the top of my head. First, by default ora_rowscn is the same for all rows in a block , even if the rows were modified at different times. If the table was created with rowdependencies then it will only show the rows actually modified.

Second, the SCN to timestamp translation is only available during the redo/flashback window, though you should be OK for 120 hours, so if you're looking on the same day or soon afterwards you shoudl be OK. See this for a bit more info.

And third, you need to be a bit careful about when and how you query the data. If a change is made just before midnight but isn't committed until after midnight, and you run your query exactly at midnight to see the last changes for the day, then you won't see the uncommitted change. And if you query again later then you won't see it because it's now a change yesterday.

Also see this .