I am exploring use of Oracle EBR in for hot patching of our application database. I have searched in Google regarding EBR. What I understand is that EBR will allow user to have many versions of same DB object like PL/SQL procedure etc. User will be able to access a new version when it is enabled for that particular user and the transition will be seamless for existing user i.e. existing sessions will be unaffected. But I am not able to understand how it will not affect the existing sessions. For example if user "X" is in middle of a transaction that uses a DB session and a new EBR version is enabled for that user, won't it affect the current DB session? or will the current DB session won't see the existing EBR and only new sessions will see the new version. Please let me know your opinion.
An edition is enabled at the session level not at the user level. If user X has a dozen sessions, each of those sessions could be using a different edition.
It really wouldn't make sense to try to change the edition the session is using in the middle of a transaction. I can't imagine why you'd want to try. And I'd wager heavily that it wouldn't work.
If you're using edition-based redefinition, you would realistically enable the new edition for new sessions or between transactions in a particular session. Commonly, you'd do a rolling upgrade where each application server gets rebooted and the connection pool set to use the new edition while the connection pools on the other servers remain using the old edition.
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We have application where all logic is implemented in oracle database using pl/sql.
We have different oracle databases for development and production.
When developer make changes in development database after testing we move changes from development database to production database using schema compare tool of toad. Problem here is that developer must have password of production database. We want only admin to know this password.
Can somebody advice me better way of moving changes between databases without need of having production database password, what is best practice for this ?
I posted this question on oracle OTN forums and got some advices there. Maybe it will be interesting for somebody.
Her is a link
I do not recommend to use comparison tools for generating of database migration scripts.
Development and production databases (and also test databases) must be identical except for current changes made by developers in development databases. Generally speaking this assertion is not correct, because there are many kinds of differencies between development and production databases, e.g. partitioned objects, additional objects for audit (triggers, tables), replication-based objects (snapshots), different tablespaces etc.
Every developer must know, what changes were made by him and applied to development database.
If developer was able to change schema and data in developer database, then he/she must be able to create programs for these DDL and DML changes.
To delegate the same developer an ability to run these migration programs on production database is a bad idea. But if you don't have a better way of database migration, then you can use one of following:
1. Configure Oracle authentication by OS. OS authentication allows Oracle to pass
control of user authentication to the operating system.
2. TOAD can save passwords without disclose them. DBA will insert required password
to local TOAD installation at developer PC (if developers use PC).
My work uses Oracle 10G and is planning on installing Apex. In the meantime, I have downloaded Oracle XE and have taught myself APEX on it; however, I can only access users/tablespaces that I have made in the XE database. What I would like to do is use the XE's Apex to access the users/tablespaces in the production databases of my work.
My colleague says that this should be possible because my workstation is connected to the server, and that there should be a way to configure access from my XE's Apex to the 10g's databases, such as by setting up an appropriate DAD.
I see nothing in the Apex user interface to allow this. I've read every word of the Apex documentation but nothing registered.
XE uses the embedded PL/SQL gateway, as opposed to 10/11G which uses either an Apex Listener or an HTTP Server with the mod_plsql plugin.
Thank you,
Matthew Moisen
I have done this before where we didn't have access to the actual database hosting the data to be worked with save for the standard port 1521 listener access. Apex at the time was new enough to the organization that the DBA's also had a voodoo taboo on using their database server as a webserver gateway as well. You can use your database instance with APEX installed as a "middle tier" or app server with the following steps:
Set up an account on your 10g database that is accessible remotely via dblink.
Set up dblinks to your 10g database table on your workstation with XE installed, use the account and connection information for the 10g database as set up in (1). Note, you may have to update a TNS names file or explicitly indicate your host/networking settings within the dblink itself.
For simple sanity and simplicity in coding your apex projects, set up synonyms for all your dblinked objects (i.e., table1 for table1#dblink) so you're not referencing the dblinks directly in your apex code. Making changes later will be easier if you adhere to this.
That's it. One proviso is that you need to know that LOBs will not work with the out-of-the-box functionality of APEX driven DML operations while using dblinks. This may have changed with the newest version. One workaround you may consider is trying to use a stored procedure which passes your LOB data as a input parameter which will do your DML operation for you.
Otherwise, this approach works nicely. The place where I implemented this model has several production level apps, a test and a development tier all using servers hosting APEX separately from the actual data sources. We used Oracle Standard Edition One (for the support), but Oracle XE should work as well since APEX is the platform in common between either Oracle version.
My delayed job has something to do with exporting slightly edited version of most of the tables in the app's database, and while doing so, it is critical that none of the current data is being edited.
Is it possible to lock the entire database while running this delayed job?
More Information:
The database to be exported is in PostgreSQL, Heroku's postgresql database, to be more specific.
The flow is something like (all below should be done automatically by the code):
site would be put in maintenance mode,
freeze then export the database, then
when exporting is complete, re-activate the site back
Given there is not a lot of information with your question, I am going to answer you as best I can.
1) What is the database type and model? Is it a standalone DB like MS Access or Informix SE?
2) If not a standalone engine, does this database support replication. I used to work a lot with MS SQL Server, and replication had implications while the database was live and being edited. That is the implications were whether edited data was replicated. In this case, consult the docs. Is it an option to use replication to preserve the current database?
3) What kind of task is this? It sounds like maintenance. Our Informix SE databases lock when being imported or exported. On the production server, it is my job to make sure no local server applications are trying to access the locked DB, and that our external payments web site cannot interfere while the db is locked.
4) If this is a production site that is not in maintenance mode, then I suggest you probably do not want to lock an entire database.
I am sorry for not answering your question directly, but more information is needed like are you asking if this can be done from the Ruby DB interface on some model of db.
We have some databases in a single SQL Server 2000 instance, one of them being a sandbox. My boss needs to be able to restore fresh data over the sandbox using a utility I don't have the source to. Such restores fail if anyone is connected to the sandbox.
Another app I have accessing it uses connection pooling, and also there might be people using other apps to access the sandbox that I can't control.
How can I boot everyone off the sandbox, including the pooled connections, without touching any of the other databases running on the same instance?
(I've seen solutions out there that use Management Studio 2008 (from 2008 Express), but a) I need to be able to do it from the command line or a script somehow so my boss can run it without installing Management Studio, and b) the context menu options they talked about didn't seem to be there anyway.)
I've found it on the web:
ALTER DATABASE db SET SINGLE_USER WITH ROLLBACK IMMEDIATE
create a sp that run this restores, and then restore it to regular.
(ALTER DATABASE foo SET MULTI_USER;)
Is there any technology out there that will allow you to do side-by-side updates of production schemas?
The goal is to have zero down time when applying updates to a schema in production.
Weblogic 10 has a similar feature for their Java EE apps where by you deploy the new version of the app and new connections go to the new app, while the existing connections continue to the old app. When all the old connections complete/timeout, the old app is retired and the new app continues on...zero down time.
Is there something similar in Oracle?
Yes. There is online redefinition package.
DBMS_Redefinition
But I doubt this will give you zero downtime, this doesn't account for every possible change to a schema. This lets you do some table changes. I think you need to define zero and how extensive the changes you want to make. Usually if you change the database, you have to change your client as well. If you changed your database, how would the client switch automatically from the old proc signature to the new proc signature - Instantaneously?
Databases don't work like apps. There either is a FK from tableA to tableB or there isn't... it can't not be there for current connection and exist only for new connection in the same manner as your application can. Databases just aren't the same.
That being said, there is rumor that Oracle is working on package versioning... so you could connect to a specific version of a package to make such a migration simpler. But again... that would work for packages, DBMS_redef would work for tables... but that's not the sum total of your database.
Oracle release today 11gr2, it has edition-based redefinition: http://download.oracle.com/docs/cd/E11882_01/server.112/e10881/chapter1.htm#NEWFTCH1
Depends what you mean, or include, in "schema".
If you want to add or drop an index, that can be done "in-flight", although it will require a lock which may halt activity for a time. In the latest Oracle versions, it doesn't need to hold the lock for the entire time it takes to build the index, just for a moment to lock in the change. If you have short-duration transactions it shouldn't be noticeable.
In some cases that applies to tables as well (eg adding a nullable or default column).
If you use PL/SQL (especially packages), things can be a little more complicated. Enhancements were mooted for 11gR1 to enable the in-flight application upgrade, but it got pushed out and is now expected in 11gR2 (probably out first half next year).
In the meantime, a workaround is a multi-schema solution. Say your data sits in one schema ("yellow") and your current application code is running in "blue" schema, you load your new application into "green schema". You switch your connections, one by one, from blue to green. Once your connections are all using "green", you can retire "blue" until your next upgrade (when "blue" becomes the new app and "green" is retired).
If you have a genuine 24/7 system, you'll probably always have to stage some upgrades. For example, add a new column as optional, upgrade the application to set it, then make it mandatory (possibly with some data change script for pre-existing rows).