I use Oracle 'DBA_TAB_COLUMNS' quite extensively. Just have a general question about this view - Is this view 'DBA_TAB_COLUMNS' system-generated, and therefore gets updated automatically?
The reason I'm asking is, seems that there are some columns that get added into 'DBA_TAB_COLUMNS' all of a sudden. These columns have been in my Oracle database for a long time, so I'm wondering why suddenly they got added into DBA_TAB_COLUMNS.
For example, if I have a table called TABLE_TEST and there are 2 columns in it: COL_1 and COL_2, I think these 2 columns get added into DBA_TAB_COLUMNS immediately after TABLE_TEST gets created, right? Or, is there something the DBA needs to do in order to refresh DBA_TAB_COLUMNS?
I've read the Oracle documentation about it but didn't find anything specific about this question, so could someone please advise?
Today, someone in my system has updated unexpected statement. So that makes my system run incorrect.
Now, I would like to see log who (or which session) did it. May I find it in AWR report ? And if I can find it in AWR report, where is it particularly ?
Thanks so much !
The change could be in many sources, depending on how it was made. Only the last option, Log Miner, will give you exactly everything you want. But it also requires the most effort. Some sources won't tell you the session, but maybe just seeing the relevant SQL will be enough to figure out who did it.
V$SQL - All SQL statements go in there, but they age out of the shared pool so you need to search quickly. If they used a unique query you may be able to find it with something like select * from v$sql where lower(sql_text) like '%table_name%';.
AWR - You may be able to find the SQL in select * from dba_hist_sqltext where lower(sql_text) like '%table_name%';, and then if you're lucky you can find out some session information from select * from dba_hist_active_sess_history where sql_id = '<sql id>';. Active Session History only samples activity, if the query ran very quickly there's a good chance it won't be in there.
Flashback query - If you're lucky the UNDO is still around and you can see exactly how it changed from a flashback query. This may give you the exact time, and what changed. select VERSIONS_STARTSCN, VERSIONS_STARTTIME, VERSIONS_ENDSCN, VERSIONS_ENDTIME, VERSIONS_XID, VERSIONS_OPERATION, your_table.* from your_table versions between scn minvalue and maxvalue;
Log Miner - I haven't used this, but supposedly it's the perfect tool for this job. Read more about it in the documentation.
I'm trying to move data in between two oracle databases say SOURCE_A and DEST_B. I have created a dblink (LINK_A) using TOAD on DEST_B to SOURCE_A to copy data from the tables. Dblink creation was fine, but when I used a select statement like below, I see no data except column names.
SELECT * FROM TABLE_A#LINK_A;
Could you please help me understand what am I doing wrong or missing here. I tried running a DESC on the TABLE_A using the link and it worked fine. Not sure why its not pulling any data from the SOURCE_A database.
Any help is greatly appreciated. Thanks.
Alright, with many trial and errors, I managed to get a solution that works for me in this SO question.
I used the technique provided by - Jeremy Scoggins and it worked like charm. I was able to move data using toad and its perfect. Thanks to all of you for your time and support.
Appreciate it.
Someone (or something) actually updated a value in my table wrongly. I am trying to find out when the update happened. Unfortunately, there is no audit trigger being created for the said table.
Is there other ways or logs that I can check and verify what SQL statements were run at what time?
I had tried to look at v$sql table, but I don't think that table is capturing all the SQL statements being performed on the database. E.g. I specifically did an UPDATE statement, but it is not captured in the v$sql table.
Can I look at the redo.log? However, I do not know how to interpret this log.
Your only real option is logminer, which isn't for the faint of heart.
The documentation is here: http://docs.oracle.com/cd/B19306_01/server.102/b14215/logminer.htm
v$sql rows may get aged out after a while. Did you account for case sensitivity when looking in v$sql?
select * from v$sql where upper(sql_fulltext) like '%UPDATE%';
Can I find out when the last INSERT, UPDATE or DELETE statement was performed on a table in an Oracle database and if so, how?
A little background: The Oracle version is 10g. I have a batch application that runs regularly, reads data from a single Oracle table and writes it into a file. I would like to skip this if the data hasn't changed since the last time the job ran.
The application is written in C++ and communicates with Oracle via OCI. It logs into Oracle with a "normal" user, so I can't use any special admin stuff.
Edit: Okay, "Special Admin Stuff" wasn't exactly a good description. What I mean is: I can't do anything besides SELECTing from tables and calling stored procedures. Changing anything about the database itself (like adding triggers), is sadly not an option if want to get it done before 2010.
I'm really late to this party but here's how I did it:
SELECT SCN_TO_TIMESTAMP(MAX(ora_rowscn)) from myTable;
It's close enough for my purposes.
Since you are on 10g, you could potentially use the ORA_ROWSCN pseudocolumn. That gives you an upper bound of the last SCN (system change number) that caused a change in the row. Since this is an increasing sequence, you could store off the maximum ORA_ROWSCN that you've seen and then look only for data with an SCN greater than that.
By default, ORA_ROWSCN is actually maintained at the block level, so a change to any row in a block will change the ORA_ROWSCN for all rows in the block. This is probably quite sufficient if the intention is to minimize the number of rows you process multiple times with no changes if we're talking about "normal" data access patterns. You can rebuild the table with ROWDEPENDENCIES which will cause the ORA_ROWSCN to be tracked at the row level, which gives you more granular information but requires a one-time effort to rebuild the table.
Another option would be to configure something like Change Data Capture (CDC) and to make your OCI application a subscriber to changes to the table, but that also requires a one-time effort to configure CDC.
Ask your DBA about auditing. He can start an audit with a simple command like :
AUDIT INSERT ON user.table
Then you can query the table USER_AUDIT_OBJECT to determine if there has been an insert on your table since the last export.
google for Oracle auditing for more info...
SELECT * FROM all_tab_modifications;
Could you run a checksum of some sort on the result and store that locally? Then when your application queries the database, you can compare its checksum and determine if you should import it?
It looks like you may be able to use the ORA_HASH function to accomplish this.
Update: Another good resource: 10g’s ORA_HASH function to determine if two Oracle tables’ data are equal
Oracle can watch tables for changes and when a change occurs can execute a callback function in PL/SQL or OCI. The callback gets an object that's a collection of tables which changed, and that has a collection of rowid which changed, and the type of action, Ins, upd, del.
So you don't even go to the table, you sit and wait to be called. You'll only go if there are changes to write.
It's called Database Change Notification. It's much simpler than CDC as Justin mentioned, but both require some fancy admin stuff. The good part is that neither of these require changes to the APPLICATION.
The caveat is that CDC is fine for high volume tables, DCN is not.
If the auditing is enabled on the server, just simply use
SELECT *
FROM ALL_TAB_MODIFICATIONS
WHERE TABLE_NAME IN ()
You would need to add a trigger on insert, update, delete that sets a value in another table to sysdate.
When you run application, it would read the value and save it somewhere so that the next time it is run it has a reference to compare.
Would you consider that "Special Admin Stuff"?
It would be better to describe what you're actually doing so you get clearer answers.
How long does the batch process take to write the file? It may be easiest to let it go ahead and then compare the file against a copy of the file from the previous run to see if they are identical.
If any one is still looking for an answer they can use Oracle Database Change Notification feature coming with Oracle 10g. It requires CHANGE NOTIFICATION system privilege. You can register listeners when to trigger a notification back to the application.
Please use the below statement
select * from all_objects ao where ao.OBJECT_TYPE = 'TABLE' and ao.OWNER = 'YOUR_SCHEMA_NAME'