Once an Oracle materialized view refreshes successfully can it be rolled back or put back to what it was prior to the refresh? Can the materialized view log on the master table be used if there is one?
I have an etl processes which has several procedures and materialized view refreshes. The way it is supposed to work if something fails than every thing that was done prior to it is rolled back. If something fails after a materialized view has been refreshed can the refresh be rolled back?
You can not manually rollback a materialized view refresh, once the refresh procedure is complete it has committed.
What you can do is lump all your materialized view refreshes into the same dbms_mview.refresh call. The default arguments for refresh_after_errors, atomic_refresh mean that if one of the MView refreshes in your list fail, the whole thing will be rolled back.
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I have a requirement in which I need to build a materialized view on a transaction table, though it has about 671348 records, it takes more than 15 mins for executing the underlying materialized query.
The base table is refreshed every Tuesday
Please let me know what type of refresh I can use for materialized view(full or fast)
Also please let me know the syntax for refreshing the materialized view every tuesday.
I have a stored procedure and materialized view in same DB.The purpose of this procedure is to refresh the materialized view.
When I run the procedure directly from db mview is refreshed properly means the mview returns more data.
Now I done an informatica mapping ,this mapping call the store procedure to refresh the mview.
It runs properly but mview does not refresh properly that means the mview contains less data rather than first try.
My Question is that why the materialized view does not contain the all data after refreshing through informatica?
materialized view refresh type is complete.
Most likely the problem is that you've not invoked the stored procedure successfully at all but have convinced yourself that you have. Please include the excerpt of the session logs that confirms the stored procedure ran successfully (also check the connection used when the stored procedure call is made is the same as it should be i.e. you may have chosen a connection when writing the mapping but in the workflow it will be set to the default which most likely isnt the same)
I have a materialized view I would like to alter to on commit (from on demand) using fast refresh.
However I constantly get
ora-32337 cannot alter materialized view with pending changes refresh on commit
even directly after a refresh (and knowing that no change was done).
What could be the cause for this? The MV uses outer joins, could that be an issue? (MV log is available for all tables)
As #eaolson said you should just drop the materialized view and recreate it as refresh on commit. This the only way..
In one of our applications, we have a massive Materialized View that refreshes three times a day, and takes seven hours to refresh. (Not ideal, I know). This perplexed me, because I surely thought that users and sessions could not access this materialized view while it was being refreshed, but apparently they can!. (The type of refresh is a complete refresh)
During a complete refresh, to my understanding, the existing dataset is dropped and the query is then re-executed. If this is true, then how are users/other sessions able to access the materialized view while the materialized view is being refreshed?
There are two different ways that a complete refresh can happen-- an atomic refresh or a non-atomic refresh. An atomic refresh simply issues a DELETE to delete all the rows in the materialized view and then does an INSERT to insert the new data. This is all within a single transaction so Oracle's standard multi-version read consistency architecture lets Oracle show other sessions the old data until the refresh completes. In a non-atomic refresh, Oracle does a TRUNCATE on the materialized view and then a direct-path INSERT to insert the new data. This is substantially more efficient but since TRUNCATE is DDL, it means that the old data is not visible to other sessions during the refresh.
I have the following materialized view -
CREATE MATERIALIZED VIEW TESTRESULT
ON PREBUILT TABLE WITH REDUCED PRECISION
REFRESH FORCE ON DEMAND
WITH PRIMARY KEY
AS
SELECT...
FROM...
WHERE...
This materialized view has no backing MATERIALIZED VIEW LOG. As seen in the clause above this MV has "ON DEMAND" specifies, and according to Oracle documentation,
"[ON DEMAND] indicate[s] that the materialized
view will be refreshed on demand by
calling one of the three DBMS_MVIEW
refresh procedures."
When I call DBMS_MVIEW.REFRESH('TESTRESULT') , what is occuring? Is it manually checking each record to see if it has been updated?
Oracle Version: 10g
By default (and this default changes in different versions of Oracle), that will do a full, atomic refresh on the materialized view. That means that the data in the materialized view will be deleted, the underlying query will be re-executed, and the results will be loaded into the materialized view. You can make the refresh more efficient by passing in a value of FALSE for the ATOMIC_REFRESH parameter, i.e.
dbms_mview.refresh( 'TESTRESULT', atomic_refresh => false );
That will cause the materialized view to be truncated, the query re-executed, and the results inserted into the materialized view via a direct path insert. That will be more efficient than an atomic refresh but the materialized view will be empty during the refresh.