We are moving from an amazon ec2 database to an amazon rds database. Most of the tables are small and could be moved using sql developer copy commands but a couple are bigger (3M+ records). In order to speed those up, I created database links between the two system. Those work fine. I then ran the following:
create table schema.tablename as select * from schema.tablename#ec2db;
ec2db is the old database. The table there contains 3,503,064 records. However the NEW databse table only contains 3,454,685 records. No errors were generated during the create table statement. This is repeatable (ie: I drop the table and run it again, and it loads the same number of records.)
Any ideas why this would happen? Why would the contents of a table when I do a select (*) not be the same as the contents of the same table (fully specified) when I do a create table?
Related
I want to ask you if there is a solution to auto-synchronize a table ,e.g., every one minute based on view created in oracle.
This view is using data from another table. I've created a trigger but I noticed a big slowness in database whenever a user update a column or insert a row.
Furthermore, I've tested to create a job schedule on the specified table (Which I wanted to be synchronized with the view), however we don't have the privilege to do this.
Is there any other way to keep data updated between the table and the view ?
PS : I'm using toad for oracle V 12.9.0.71
A materialized view in Oracle is a database object that contains the results of a query. They are local copies of data located remotely, or are used to create summary tables based on aggregations of a table's data. Materialized views, which store data based on remote tables, are also known as snapshots.
Example:
SQL> CREATE MATERIALIZED VIEW mv_emp_pk
REFRESH FAST START WITH SYSDATE
NEXT SYSDATE + 1/48
WITH PRIMARY KEY
AS SELECT * FROM emp#remote_db;
You can use cronjob or dbms_jobs to schedule a snapshot.
I have the following scenario and need to solve it in ORACLE:
Table A is on a DB-server
Table B is on a different server
Table A will be populated with data.
Whenever something is inserted to Table A, i want to copy it to Table B.
Table B nearly has similar columns, but sometimes I just want to get
the content from 2 columns from tableA and concatenate it and save it to
Table B.
I am not very familiar with ORACLE, but after researching on GOOGLE
some say that you can do it with TRIGGERS or VIEWS, how would you do it?
So in general, there is a table which will be populated and its content
should be copien to a different table.
This is the solution I came up so far
create public database link
other_db
connect to
user
identified by
pw
using 'tns-entry';
CREATE TRIGGER modify_remote_my_table
AFTER INSERT ON my_table
BEGIN INSERT INTO ....?
END;
/
How can I select the latest row that was inserted?
If the databases of these two tables are in two different servers, then you will need a database link (db-link) to be created in Table A schema so that it can access(read/write) the Table B data using db-link.
Step 1: Create a database link in Table A server db pointing to Table B server DB
Step 2: Create a trigger for Table A, which helps in inserting data to the table B using database link. You can customize ( concatenate the values) inside the trigger before inserting it into table B.
This link should help you
http://searchoracle.techtarget.com/tip/How-to-create-a-database-link-in-Oracle
Yes you can do this with triggers. But there may be a few disadvantages.
What if database B is not available? -> Exception handling in you trigger.
What if database B was not available for 2h? You inserted data into database A which is now missing in database B. -> Do crazy things with temporarily inserting it into a cache table in database A.
Performance. Well, the performance for inserting a lot of data will be ugly. Each time you insert data, Oracle will start the PL/SQL engine to insert the data into the remote database.
Maybe you could think about using MViews (Materialized Views) to replicate the data via database link. Later you can build your queries so that they access tables from database B and add the required data from database A by joining the MViews.
You can also use fast refresh to replicate the data (almost) realtime.
From perspective of an Oracle Database Admin this would make a lot more sense than the trigger approach.
try this code
database links are considered rather insecure and oracle own options are having licences associated these days, some of the other options are deprecated as well.
https://gist.github.com/anonymous/e3051239ba401e416565cdd912e0de8c
uses ora_rowscn to sync tables across two different oracle databases.
Few days ago there was network problems. Also one of the database harddisk partition storage ran out of space but it has been fixed now.
Additional note: one of the DBA compressed the archive log to spare some space during the problem happened.
One of the outcome was that now I CANNOT select one table from other Oracle database on the other server if using schema name prefix.
For example if I run query from one of the schema/user in database1 from Toad or sqlplus:
select * from office.room#database2
The query runs forever and never stops.
Usually it's not a problem. The other tables are fine; I can select them using office.*#database2 query.
The other odd thing is that if I use SYNONYM, I CAN select that table. Let's say that table has synonym 'room' on db2 database, this query is OK:
select * from room#database2
The table itself on database2 is OK, meaning that if I login to schema "office" on database database2, I can select the table data.
I still can not find out what causes this problem.
New founding, I can select the table with no hang up if I add WHERE filter or I select the columns, for example :
select * from office.room#database2 where roomnumber='A';
or
select roomname, rumnumber from office.room#database2;
But the select * from office.room#database2 still hang up.
I have a question: I have a table (say tableA) in a database (say dbA) and I need to mirror tableA as another table (say tableB) in another database (say dbB).
I know this can be done via (materialised) view or via informatica. But by problem is that I need to sync DDL as well. For example if a column is added in tableA, the column should automatically reflect in tableB.
Can this be done anyway directly via oracle or Informatica.
(or I will have to write a procedure to sync table on basis of all_tab_cols).
Yes, you could:
create another database as a logical standby database with Data Guard
use Oracle Streams
I would use (2) if you just need a single table in the other database or (1) if you need an entire schema (or more).
I Want to know the sourse of this table. How it is calculated from the table. I am using sql server r2 2008 and I searched for that table, but it is not there. It is formed by manipulating some rows of different tables. Is there any way to find it. I searched the corresponding table in VB 6 also. but it is not there. Is there Any way to find the source table?
Source in local variables is :
"Select * From #70554TempShiz52"
Tables with name starting with # or ## are temporary tables (Quick Overview: Temporary Tables in SQL Server 2005).
The table exists only as long as the connection in which table was created exists. It is accessible only from connection which has created it.
To find the table you should look for an appropriate statement CREATE TABLE #70554TempShiz52 in the code.
The table is exists in tempdb database. An admin can see it there using ssms (only when the connection is still open and table was not dropped). I usually put a breakpoint to achieve desired state. The name of the table looks like #70554TempShiz52__________...some number (to distinguish tables from other users).
I can be useful to use a name starting with ## for debugging because such a table is visible from other connections.