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Dirt Cheap Oracle step #6 of 6: Migrate the Apex applications

September 27, 2007

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I’ve got my Linux server running now, and I can access it from anywhere on the Internet. I can even do application development remotely in Apex, which is fun to show off.

Now, I have a number of small Apex applications (mainly personal use) which are running on my Windows PC, and I want to transfer them all to Linux. The steps I take are as follows:

  1. Backup
  2. Export the applications
  3. Export the data
  4. Export the workspaces
  5. Set up tablespaces
  6. Import the workspaces
  7. Import the data
  8. Import the applications
  9. Test
  10. Backup

Instead of trying to just copy everything across in one big bang, I wanted to selectively move certain applications and data across, with a few changes along the way. For example, one application was storing a lot of images in BLOBs in a table, but in the new database these are going to be stored on the filesystem to save space in the database. So I’ll only export the data for the other tables, not including the BLOBs (if needed I could export the data to files on the filesystem, but as it happens I have already been keeping copies of all these images on the filesystem anyway, so it’ll be a simple matter to transfer them across). Another change is that one workspace uses a schema name which I’d like to change in the new database.

In detail:

1. Backup

The docs always say “take a backup” before you do anything. On this occasion I decide to actually do this for once. So I do a complete export of the database on the Linux PC.

While that’s running, I switch over to the Windows box and:

2. Export the applications

I’ve only got half a dozen applications I want to transfer across, so it’s not too big a deal to log into each workspace, select an application, click Export/Import, choose Export, and click Export Application.

3. Export the data

I’ve only got a small amount of data and with one exception I just want to get exports of all objects for the various schemas used by the workspaces, so I use the exp utility, one at a time for each schema. The one exception is the schema with the BLOBs – in that case, I choose the mode that allows me to select individual objects to export. Not too hard, as long as I don’t have to do it every day!

The docs all say to use the new Data Pump feature. So “do as I say, not as I do”…

4. Export the workspaces

This is a very useful feature of Apex – it takes care of creating workspaces, schemas and users along with their privileges. To do this, I log into the Apex Administration function (e.g. via the INTERNAL workspace), select Manage Workspaces, and click Export Workspace. Select each workspace in turn and click Export Workspace. Choose UNIX for the file format and click Save File.

Ok, I’ve got all the files I need. I put them on a transfer disk (I’ve got a share on the Windows PC) and switch back to Linux. The backup I started earlier has finished, so now I can start importing it all.

5. Set up tablespaces

I decided to set up my tablespaces manually, so I can specify the file sizes and everything to my exact requirements. E.G.:

CREATE TABLESPACE FLOW_1DATAFILE '/usr/lib/oracle/xe/oradata/XE/FLOW_1.dbf'SIZE 5M NEXT 1M MAXSIZE 100M;

6. Import the workspaces

What could be simpler? Apex Admin, Manage Workspaces, Import Workspace, pick the workspace export file created in step 4, and click Install. I choose the option to create new schemas. In one case I change the schema name (mentioned above).

7. Import the data

Simple matter of running the imp command in a Linux command window. I got quite a few compilation errors due to dependencies between schemas (including some schemas that I’d decided not to import), but once they’re resolved it’s all good.

8. Import the applications

Log into each workspace and click Application Builder, Import. Choose the application exported in step 2 above. Click Next and I’m done!

9. Test

I use all my test cases that I’ve prepared thoroughly beforehand (not!)… ha. Well, in fact I just opened each application and checked a few pages here and there. A few bits and bobs not working but soon sorted out.

10. Backup

I take another backup to lock down everything in a known working state, and it’s all done!

I’m sure there’s two dozen other ways I could have done all this, some of which perhaps easier, more efficient or just more exciting. Certainly I wouldn’t advocate all these steps for a large installation. It’ll depend on your requirements. Another approach would have been to do a complete export of Oracle and import the whole thing.

Please add any comments to any of the posts in this series about your experiences in these areas, as others have done already. We can all learn from each other, and that’s what I love about blogging. Thanks!

Thanks for reading – I hope you’ve enjoyed this little series on “Dirt Cheap Oracle”. I hope I’ve demonstrated that it is possible, and relatively easy, to obtain and set up a cheap Linux box, and add to your Apex/Oracle experience skills in web server configuration and home networking, all for free.

I can see this kind of setup being really useful for small non-profit organisations like community groups, charities, and religious organisations. Get out there and give it a go!

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