In my Oracle instance I have a table. It existed just fine for many years without problems, I run thousands of queries per day on it (through my software), mostly selects and inserts, with rare (once-a-week) updates.
Today, a week after the last update, I ran an update against it and it failed with an ORA-00942: table or view does not exist.
I am the owner of that table. I'm pretty sure that database didn't change much during the week, certainly not this table.
I can select from it just fine: select * from table_x, but updates and inserts fail: insert into table_x select * from table_x where 1 = 0 with the weird ORA-00942.
Since I'm the owner, the usual visibility and privilege problems don't seem to apply, and googling, sadly, doesn't help. I'm sure I'm missing something really simple, so any suggestions are very welcome.
How did I make an Oracle table read-only (or invisible) for myself (the owner)?
It's partitioned (not sure if that helps). It's about 50GB in size, half of that indexes (not sure if that helps either).
EDIT: Here's a screenshot of the sample statement from PL/SQL Developer:
Once I ran the same situation, according to the trace file and little googling which referenced to Materialized View Log which is associated with master table.
Use the following command to drop the materialized view log
DROP MATERIALIZED VIEW LOG ON <table_x>
Related
Is it possible to create a hive view on top of a nonexistent hive table or views?. This ability will help us deploy the hive DDL without any order at the time of refresh (migrating tables or views from one environment to another). In our environment, we have views built on top of another view. If we deploy them in any order, with the default setup some of the views may fail saying the underlying table/view doesn't exist. Looking to see if we can turn off the metadata lookup from hive metastore so that the type checks are not done at the time of view creation. It can be enforced after the deployment or at the time of querying the view for data retrieval because by that time all the views/tables will be completely deployed and there won't be any type checking related errors.
I checked on the internet for pointers but I couldn't find any. Any suggestions in this regard will be helpful to us.
Thanks in advance.
Add IF NOT EXISTS to all create statements and run all several times until errors disappear.
If executed 2 times in the wrong order like this, second run will succeed without any error:
drop view if exists my_view;
create view if not exists my_view as select from table1; --fails first time, succeeds on second run
drop table if exists table1;
create table if not exists table1(id int);
Recently I need to create several materialized views on Oracle 19c, all of the base tables are locate on a remote oracle database, the query uses dblink to connect the tables, and fast refresh is not allowed.
Most of them can complete refreshment in seconds after add some hints on them, like use_hash etc. But when create the one with union on the query, the hints do not work at all, luckily there is only one union, so I split the query to two parts, but another issue emerges, one of the materialized view only takes no more than 10 seconds for creation, but it takes hours even days cannot complete refreshment. I searched on web and got below answers:
use dbms_mview.refresh(mv_name, 'C', atomic_refresh=>false). This solution does not work.
fast refresh. The solution does not allowed.
Instead to do refresh, re-create the materialized view every time, it is a workaround, but not a solution.
Use hint optimizer_features_enable(9.0.0), I simulated the issue on a table (as I cannot insert into...select... on materialized view), seems the hint does work, but when I tried to apply the hint on the materialized view, from the execution plan I can see that the hint has been ignored. I also tried to add alter session set optimizer_features_enable='9.0.0' on scheduler job before the dbms_refresh.refresh(mv_name), but it does not work. Would like to know are there anyone have any idea on this problem? Thank you.
Jonathan from oracle community just gave me a solution for my specific query. As all the fields of my query come from remote database except the systimestamp function, so I can separate the function to the outer select statement and make all the remote fields as sub-select statement then add no_merge hint to it, this will make remote database optimizer come to play.
SELECT systimestamp, v.*
FROM (
my original query with /*+ no_merge */
) v;
I’ve been tasked with doing some housekeeping on an Oracle schema I have access to. In a nutshell, I’d like to drop any tables that have not been ‘used’ in the last 3 months (tables that haven’t been queried or had data manipulated in the last 3 months). I have read/write access to the schema but I’m not a DBA; I run relatively basic DML/DDL queries in Oracle.
I’m trying to figure out if there’s a way for me to identify old/redundant tables; here’s what I’ve tried (mostly unsuccessfully)
USER_TABLES was my first port of call, but the LAST_ANALYZED date in this table doesn’t seem to be the last modified/queried date I’m looking for
Googling has brought DBA_Hist tables to my attention, I’ve tried querying some of these (i.e. DBA_HIST_SYSSTAT) but I’m confronted with (ORA-00942: table or view does not exist)
I’ve also tried querying V$SESSION_WAIT, V$ACTIVE_SESSION_HISTORY and V$SEGMENT_STATISTICS, but I get the same ORA-00942 error
I’d be grateful for any advice about whether the options above actually offer the sort of information I need about tables, and if so what I can do to work around the errors I’m getting. Alternatively, are there any other options that I could explore?
Probably the easiest thing to do, to be 100% sure, is to enable auditing on the Oracle tables that you're interested in (possibly all of them). Once enabled, Oracle has an audit table (dba_audit_trail) that you can query to find if the table(s) have been accessed. You can enable auditing by issuing: AUDIT on . BY SESSION;
I chose "by session" so that you only get a single record per session, no matter how many times the session performs the operation (to minimize the records in the audit table).
Example:
audit select on bob.inventory by session;
Then you can query the dba_audit_trail after some time passes to see if any records show up for that table.
You can disable auditing by issuing the "noaudit" command.
Hope that helps.
-Jim
I'm not a DBA, but let's hope I'll be able to describe our current Problem.
We have a rather large partitioned table that we reorganize regularly via dbms_redefinition.start_redef_table(..) etc. . We had collision with other stuff going on in our database, so this has failed a few times in the past. But it hasn't failed in the last few month. Since the last failure we have reorganized each of the partitions, so the table and all partitions are in a healthy state. We are not experiencing any performance issues due to possible mview updates.
Apparently after one of those failures some mlog$_xxx and rupd$_xxx objects started showing up. Today we have over 100 mlog$_xxx objects and over 30 rupd$_xxx objects. And it keeps getting more. This worries me.
Following did not work: drop materialized view log on xxx;
stating me
ORA-12002 that there is no materialized view log on xxx.
when I do: select * from dba_mviews; ... then I get no results
I'm confused now. I have a table and I have mview logs, but I have no mview in between.
We made a database copy to a test machine and I was able to drop the table. But the mlog$_xxx objects were still there.
Can somebody help me on how to clean up this mess?
we contacted Oracle Support and they suggested to delete obj$ and sum$ entries. It worked. Don't try this at home!!!
We have some Materialized views in our Oracle 9i database that were created a long time ago, by a guy no longer working here. Is there an easy (or any) method to determine whether Oracle is using these views to serve queries? If they aren't being used any more, we'd like to get rid of them. But we don't want to discover after the fact that those views are the things that allow some random report to run in less than a few hours. The answer I'm dreaming of would be something like
SELECT last_used_date FROM dba_magic
WHERE materialized_view_name = 'peters_mview'
Even more awesome would be something that could tell me what actual SQL queries were using the materialized view. I realize I may have to settle for less.
If there is a solution that requires 10g, we are upgrading soon, so those answers would be useful also.
Oracle auditing can tell you this once configured as per the docs. Once configured, enable it by "AUDIT SELECT ON {name of materialized view}". The audit trail will be in the AUD$ table in the SYS schema.
One method other than auditing would be to read the v$segment_statistics view after one refresh and before the next refresh to see if there have been any reads. You'd have to account for any automatic statistics collection jobs also.
V$SQLAREA table has two columns which help identify the queries executed by the database.
SQL_TEXT - VARCHAR2(1000) - First thousand characters of the SQL text for the current cursor
SQL_FULLTEXT - CLOB - All characters of the SQL text for the current cursor
We can use this columns to find the queries using the said materialized views