What happens with my index when I do a delete?

For test purpose I had to delete and recreate a lot of records in a database.
So I just did a delete of all the records, every time I wanted to clean up my database.

Some of these tables have a few millions of records. So after a couple of times cleaning up and re-entering data into the database,
I had the impression that the database was getting slower and slower in showing me the results of my query.

I thought that this could have something to do with my indexes but I didn't know how to fix this.

That's why I contacted a few of my expert database colleagues and they learned me the following:
The index uses a highwatermark value and every time you add a record into the table the index will raise this value.
When you do a simple delete the value of this highwatermark will be kept, so I was right in suspecting the index to be the cause of this problem.

So how do you fix this?

If you want to clean a lot of records in a database(in bulk) you have 2 possibilities to keep your indexes clean.

First option, and the one that worked best in my case was: use TRUNCATE TABLE This will remove all the content of the table and will put the 'highwatermark' back to 0.

The advantage of this that is will work a bit faster then a normal deletion.
But there is also one disadvantage however. If you want to use this you will have to disable all the foreign keys for this table before starting the truncate.

So doing this in a live database is not really the best thing to do I believe :-)


The other option is just use the delete as you used to do, but after the deletion of the records use : ALTER TABLE SHRINK SPACE
You can even use the cascade option for this shrink, this will shrink all the highwatermarks of the depending objects.
This option is only available from oracle 10g.

Thanks Erwin and Hans for helping me with this!

Sometimes cornerRadius just isn't enough

Two tips for coders new to Flex... if you want to have rounded corners in mx.containers like VBox, HBox, Canvas, etc, set the borderStyle to solid and the borderThickness to 0, and then set your cornerRadius to whatever you want. If the borderStyle is left at none (default), the cornerRadius attribute seems broken and ineffective.

The second tip, if you want rounded corners at the top and bottom of your Panel, there's a property called roundedBottomCorners which defaults to false. When set to true, you will see rounding both top and bottom.

Here's an example http://www.crazedcoders.com/demos/rounded/

I should point out that this has been blogged previously here.

Invalid Embed directive in stylesheet

On a few occasions now, for no really apparent reason, suddenly our Problem Pane will be spammed with tons of messages all sort of looking like this:

Invalid Embed directive in stylesheet - can't resolve source 'Embed(source = "/assets/common.swf", symbol = "AccordionHeader_disabledOverSkin")'.

In the past, sometimes it would only happen on a mac, other times windows machines. I've tried deleting my bin folder, cleaning the project, recompiling the swf's, moving the swf's around, changing the syntax in the css ever so slightly. I've googled this on many occasions and found no clear answer. Today I decided that I needed to know what caused this and if in fact I figured it out, to share it with you.

What ended up being the root cause of our problem is that in several places in the application we were referencing image assets directly in our assets folder, i.e. /assets/delete.png, which is often the case when our designers aren't keeping up with asset creation and developers just throw some image up as a placeholder for the time being. Now it just so happened that ONE of these references was incorrect and its Embed pointed to a file that did not exist. I discovered this when I commented out our style css references in the application, and saw the error only then. It was this broken reference that caused the above error. I fixed the reference to point to the right file, did a Project clean, and all the Invalid Embed Directive errors went away.

I should note that we had over 100 references to symbols in our css, and by default Flexbuilder only shows the first 100 errors. Unluckily the "unable to resolve 'assets/deleted.png' for transcoding in ...." was error number 138 and did not show up in the list. I had to change my preferences to show all 138 errors.

So the lesson learned is that when you get spammed with this error, it could well be that only one Embed tag somewhere in your app is actually broken, and that your css and swf is probably just fine.

Webcenter Development - SRDemo

When you want to start learning Webcenter, getting a grasp of the technology, the features ... have a more practical view, you can download the SRDemo application to get you started.

When you're going through the installation-guide to set everything up, following tips can help you step-through this installation:
- modify the oc4j.cmd before installing the standalone OC4J in the SRDemo directory and make sure to define the JAVA_HOME, ORACLE_HOME and J2EE-home.
- modifications you need to perform in the adf-config.xml are setting the mds-file location correctly, which is available under your application-folder in OC4J

Invalid Embed directive in stylesheet

On a few occasions now, for no really apparent reason, suddenly our Problem Pane will be spammed with tons of messages all sort of looking like this:

Invalid Embed directive in stylesheet - can't resolve source 'Embed(source = "/assets/common.swf", symbol = "AccordionHeader_disabledOverSkin")'.

In the past, sometimes it would only happen on a mac, other times windows machines. I've tried deleting my bin folder, cleaning the project, recompiling the swf's, moving the swf's around, changing the syntax in the css ever so slightly. I've googled this on many occasions and found no clear answer. Today I decided that I needed to know what caused this and if in fact I figured it out, to share it with you.

What ended up being the root cause of our problem is that in several places in the application we were referencing image assets directly in our assets folder, i.e. /assets/delete.png, which is often the case when our designers aren't keeping up with asset creation and developers just throw some image up as a placeholder for the time being. Now it just so happened that ONE of these references was incorrect and its Embed pointed to a file that did not exist. I discovered this when I commented out our style css references in the application, and saw the error only then. It was this broken reference that caused the above error. I fixed the reference to point to the right file, did a Project clean, and all the Invalid Embed Directive errors went away.

I should note that we had over 100 references to symbols in our css, and by default Flexbuilder only shows the first 100 errors. Unluckily the "unable to resolve 'assets/deleted.png' for transcoding in ...." was error number 138 and did not show up in the list. I had to change my preferences to show all 138 errors.

So the lesson learned is that when you get spammed with this error, it could well be that only one Embed tag somewhere in your app is actually broken, and that your css and swf is probably just fine.

Webcenter Development - SRDemo

When you want to start learning Webcenter, getting a grasp of the technology, the features ... have a more practical view, you can download the SRDemo application to get you started.

When you're going through the installation-guide to set everything up, following tips can help you step-through this installation:
- modify the oc4j.cmd before installing the standalone OC4J in the SRDemo directory and make sure to define the JAVA_HOME, ORACLE_HOME and J2EE-home.
- modifications you need to perform in the adf-config.xml are setting the mds-file location correctly, which is available under your application-folder in OC4J

Invalid Embed directive in stylesheet

On a few occasions now, for no really apparent reason, suddenly our Problem Pane will be spammed with tons of messages all sort of looking like this:

Invalid Embed directive in stylesheet - can't resolve source 'Embed(source = "/assets/common.swf", symbol = "AccordionHeader_disabledOverSkin")'.

In the past, sometimes it would only happen on a mac, other times windows machines. I've tried deleting my bin folder, cleaning the project, recompiling the swf's, moving the swf's around, changing the syntax in the css ever so slightly. I've googled this on many occasions and found no clear answer. Today I decided that I needed to know what caused this and if in fact I figured it out, to share it with you.

What ended up being the root cause of our problem is that in several places in the application we were referencing image assets directly in our assets folder, i.e. /assets/delete.png, which is often the case when our designers aren't keeping up with asset creation and developers just throw some image up as a placeholder for the time being. Now it just so happened that ONE of these references was incorrect and its Embed pointed to a file that did not exist. I discovered this when I commented out our style css references in the application, and saw the error only then. It was this broken reference that caused the above error. I fixed the reference to point to the right file, did a Project clean, and all the Invalid Embed Directive errors went away.

I should note that we had over 100 references to symbols in our css, and by default Flexbuilder only shows the first 100 errors. Unluckily the "unable to resolve 'assets/deleted.png' for transcoding in ...." was error number 138 and did not show up in the list. I had to change my preferences to show all 138 errors.

So the lesson learned is that when you get spammed with this error, it could well be that only one Embed tag somewhere in your app is actually broken, and that your css and swf is probably just fine.