How do I exclude unchanged fields in Flashback query resultset?

Question

Is it possible to exclude unchanged fields in Flashback query resultset?

Consider I have following table

create table first_table
(
    id int generated as identity,
    name NVARCHAR2(1024),
    age smallint,
    notebook nclob,
    userpic clob,
    salary float
)

If the table has very frequent updates (e.g. on notebook field) following versioned query

select ROWID, VERSIONS_OPERATION, VERSIONS_STARTSCN, VERSIONS_STARTTIME, VERSIONS_XID, id, name, age, notebook, userpic, salary
from FIRST_TABLE versions between scn 1469193 and 1482882;

will pull heavy userpic value for every row even though it's the same.

Can I somehow avoid that and instead get NULLs for unchanged values ?

Answer 1

Is there a way to excluded unchanged fields from versioned response?

Not really.

Flashback uses the information found in UNDO. Flashback Data Archive stores the results from the Log files in a table.

So, you get ALL of the data when you do a Flashback query.

The common method is to use LAG + DECODE. But, I'm afraid that this will problematic for your LOB columns.

Personally, I'd pawn off the problem to the UI (Display Tier).