I am using Oracle Xpress Edition. I want to know how to select only user created tables in Oracle DB.?
I am using this query:
select * from user_tables;
But it showing 24 rows. But i have only created 6 table.I don't know why & from where other tables (like APEX$_WS_FILES,DEPT, DEMO_USERS,APEX$_ACL,, APEX$_WS_HISTORY, etc) are showing.
How to avoid those useless table.?
These tables were presumably created during any Oracle APEX related installation. You can use the below steps to get rid of them.
SELECT * FROM ALL_OBJECTS WHERE OBJECT_TYPE = 'TABLE' AND OWNER = 'your_user' ORDER BY created;
As these tables have been installed via an application, they most
probably have been installed in a small and coherent time window. What
I mean here is that probably they have been installed within a time
frame of 30 mins, 1 hr or so. So if you order them by creation time,
they will all flock to consecutive rows in the output of above query.
Identify the time frame in which they have been started and
finished installing those tables. Write the above query once again to
filter that time frame out. You are then expected to get only your
tables.
Related
I cannot seem to find a view which I created in one of my schemas within TOAD. Lets assume I don't know the exact schema in which I've created it, is there any way where I can find all the create statements which have been executed within a period of time, lets say the last days.
Thank you in advance.
If you created the view, just query ALL the views, and order by the date in which it was created.
select * from dba_objects
where object_type = 'VIEW'
order by created desc, last_ddl_time desc
We're hitting DBA_ views to make sure we look at EVERYTHING, not just the things you have PRIVS for. Switch to ALL_ views in case you lack access, and hope you didn't create the view in a schema in which your current logon can't see.
The other way to go is query the views themselves and key in on the table you think you included in the SQL behind the view.
SELECT *
FROM dba_views
WHERE UPPER (text_vc) LIKE '%EMPLOYEES%';
You might be looking for a feature called "SQL Recall" in Toad. Press F8 or View/SQL Recall. It will show you the SQL you ran in the last month or so.
I'm trying to get all the counts of tables within a specific schema (or owner). I currently am using the code at the bottom, which works, but is really slow. I know of the systems tables dba_tables and all_tables but we don't have refreshed stats within the past 1.5 years.
Are there other alternatives to this? I've tried looking at all the system tables, but none seem to have updated stats.
select
table_name,
owner as schemaname,
to_number(extractvalue(xmltype(dbms_xmlgen.getxml('select count(*) c from '||owner||'.'||table_name)),'/ROWSET/ROW/C')) as cnt
from all_tables
where lower(owner) = 'ownername'
You will have to count the rows in each table. Stats should not be used as an accurate measure of the row count. However, the fact that you have not refreshed your stats for 1.5 years is quite concerning, unless you have a database that has not had data added in that period. I suspect that you next SO post will be that of a performance problem ;)
We have a transactional database with just 2 weeks of data and another archive database which holds data older than 2 weeks. Both DBs share the same schema structure and are in separate servers. We have a reporting application which queries data from both these databases where the user selects which database he wants to query by using a dropdown selection. In order to improve user experience we are thinking to do away with the dropdown selection by making the DB selection transparent in the background. Below are the few options we had in mind
Use UNION for the 2 select queries via DB links
Query DB1 first and if no records query DB2
Since the data volume is more we are apprehensive about our choices.
Appreciate if anyone has any other suggestions on how to approach this.
In my particular opinion, the best two choices are:
always give the user the data newer than a relative date (e.g. the last three months of data).
always give the user the last n data (e.g. the newest 250 rows).
Give all data will be inefficient when you have a big dataset.
But if you want to strengthen the autonomy and protect the user's work (two important design principles in user interfaces) then you must let the user configure the relative time or the number of data items desired. Or you can also let the user explore all/older data in particular situation (e.g. using a special window, a pagination system, a particular interface or a completly new use case).
Let's see two examples. (I assume that user is querying the server with newest data and OLD is the name of the dblink you use to reference the server with the data older than two weeks. I also assume that the target table is named DATATABLE and the column with the date is called DATADATE).
To retrieve the last three months (first choice):
SELECT * FROM DATATABLE
UNION ALL
SELECT * FROM DATATABLE#OLD WHERE MONTHS_BETWEEN(SYSDATE, DATADATE) >= 3;
And, to retrieve the last 250 rows (second choice):
SELECT *
FROM (SELECT * FROM DATATABLE ORDER BY DATADATE DESC)
WHERE ROWNUM <= 250;
UNION ALL
SELECT *
FROM (SELECT * FROM DATATABLE#OLD ORDER BY DATADATE DESC)
WHERE ROWNUM <= (250 - (SELECT COUNT(*) FROM DATATABLE));
I'm using Oracle SQL Developer version 4.02.15.21.
I need to write a query that accesses multiple databases. All that I'm trying to do is get a list of all the IDs present in "TableX" (There is an instance of Table1 in each of these databases, but with different values) in each database and union all of the results together into one big list.
My problem comes with accessing more than 4 databases -- I get this error: ORA-02020: too many database links in use. I cannot change the INIT.ORA file's open_links maximum limit.
So I've tried dynamically opening/closing these links:
SELECT Local.PUID FROM TableX Local
UNION ALL
----
SELECT Xdb1.PUID FROM TableX#db1 Xdb1;
ALTER SESSION CLOSE DATABASE LINK db1
UNION ALL
----
SELECT Xdb2.PUID FROM TableX#db2 Xdb2;
ALTER SESSION CLOSE DATABASE LINK db2
UNION ALL
----
SELECT Xdb3.PUID FROM TableX#db3 Xdb3;
ALTER SESSION CLOSE DATABASE LINK db3
UNION ALL
----
SELECT Xdb4.PUID FROM TableX#db4 Xdb4;
ALTER SESSION CLOSE DATABASE LINK db4
UNION ALL
----
SELECT Xdb5.PUID FROM TableX#db5 Xdb5;
ALTER SESSION CLOSE DATABASE LINK db5
However this produces 'ORA-02081: database link is not open.' On whichever db is being closed out last.
Can someone please suggest an alternative or adjustment to the above?
Please provide a small sample of your suggestion with syntactically correct SQL if possible.
If you can't change the open_links setting, you cannot have a single query that selects from all the databases you want to query.
If your requirement is to query a large number of databases via database links, it seems highly reasonable to change the open_links setting. If you have one set of people telling you that you need to do X (query data from a large number of tables) and another set of people telling you that you cannot do X, it almost always makes sense to have those two sets of people talk and figure out which imperative wins.
If we can solve the problem without writing a single query, then you have options. You can write a bit of PL/SQL, for example, that selects the data from each table in turn and does something with it. Depending on the number of database links involved, it may make sense to write a loop that generates a dynamic SQL statement for each database link, executes the SQL, and then closes the database link.
If you want need to provide a user with the ability to run a single query that returns all the data, you can write a pipelined table function that implements this sort of loop with dynamic SQL and then let the user query the pipelined table function. This isn't really a single query that fetches the data from all the tables. But it is as close as you're likely to get without modifying the open_links limit.
I have a Materialized view in Oracle that contains a LEFT JOIN which takes a very long time to update. When I update the underlying table it takes 63914.765 s to run (yes that is almost 17 hours).
I am using a LEFT JOIN on the same table, because I want to pivot the data from rows to columns. The pivot command is not available in this Oracle version, and using a GROUP BY + CASE is not allowed on a FAST REFRESH Materialized View.
The Materialized View Log looks like this:
CREATE MATERIALIZED VIEW LOG ON Programmes_Titles
WITH PRIMARY KEY, rowid
INCLUDING NEW Values;
The Materialized View itself looks like this (it contains 700000 rows, the Programmes_Titles table contains 900000 rows):
CREATE MATERIALIZED VIEW Mv_Web_Programmes
REFRESH FAST ON COMMIT
AS
SELECT
t1.ProgrammeId,
t1.Title as MainTitle,
t2.Title as SecondaryTitle,
--Primary key
t1.Title_Id as t1_titleId,
t2.Title_Id as t2_titleId,
t1.rowid as t1_rowid,
t2.rowid as t2_rowid
FROM
Programmes_Titles t1,
Programmes_Titles t2
WHERE
t1.Titles_Group_Type = 'mainTitle'
AND t1.Programme_Id = t2.Programme_Id(+) AND t2.Titles_Group_Type(+) = 'secondaryTitle'
The UPDATE statement I use is this:
UPDATE Programmes_Titles
SET Title = 'New title'
WHERE rowid = 'AAAL4cAAEAAAftTABB'
This UPDATE statement takes 17 hours.
When using an INNER JOIN (remove the (+)'s) it takes milliseconds.
I also tried adding INDEXES on the Mv_Web_Programmes Materialized View, but that did not seem to help either. (It still runs for more than a minute, which is way to slow, I am not waiting 17 hours after every change, so it might improved the UPDATE)
So my question is: Why does is take such a long time to UPDATE the underlying table? How can I improve this?
I've managed to reproduce your problem on a 10.2.0.3 instance. The self- and outer-join seems to be the major problem (although with indexes on every column of the MV it finally did update in under a minute).
At first I thought you could use an aggregate MV:
SQL> CREATE MATERIALIZED VIEW LOG ON Programmes_Titles
2 WITH PRIMARY KEY, ROWID (programmeId, Titles_Group_Type, title)
3 INCLUDING NEW Values;
Materialized view log created
SQL> CREATE MATERIALIZED VIEW Mv_Web_Programmes
2 REFRESH FAST ON COMMIT
3 AS
4 SELECT ProgrammeId,
5 MAX(decode(t1.Titles_Group_Type, 'mainTitle', t1.Title)) MainTl,
6 MAX(decode(t1.Titles_Group_Type, 'secondaryTitle', t1.Title)) SecTl
7 FROM Programmes_Titles t1
8 GROUP BY ProgrammeId;
Materialized view created
Unfortunately, as you have noticed, as of 10g a MV that contains MIN or MAX can only be fast-refreshed on commit after insert (so called insert-only MV). The above solution would not work for update/delete (the MV would have to be refreshed manually).
You could trace your session and open the trace file to see what SQL query gets executed so that you can find if you can optimize it via indexes.
We too faced this issue recently on Oracle 11.2.0.3
In our case, it was unavoidable to to remove an 'OUTER JOIN' due to functional impact.
On investigation, it was found that Oracle was adding a nasty HASH_SH (Hash Semi Join) hint with MV refresh DML.
Nothing worked including things mentioned in following blog-
http://www.adellera.it/blog/2010/03/11/fast-refresh-of-join-only-mvs-_mv_refresh_use_stats-and-locking-log-stats/#comment-2975
In the end, a hidden hint worked...(though in general, it should be avoided by making change in application if possible)
Oracle Doc ID 1949537.1 suggests that setting the hidden _mv_refresh_use_hash_sj parameter to FALSE should prevent it using that hint.
alter session set "_mv_refresh_use_hash_sj"=FALSE;
That stopped CBO using the HASH_SJ hint.
Posting it here in the interests of others.