I’ve heard many people talk about dropping MongoDB in to their web application as a replacement for MySQL or PostgreSQL. There are no circumstances under which that is a good idea.
Schema flexibility sounds like a great idea, but the only time it’s actually useful is when the structure of your data has no value.
When you’re picking a data store, the most important thing to understand is where in your data — and where in its connections — the business value lies.
Feature Highlight: Highlights
Diigo saves the day with "highlights". Highlights let you select the important snippets on a page and store them in your library with the page's bookmark. Let's try it. Just open a page, maybe one of your old-school bookmarks or one of your new cat bookmarks, and find the information on that page you actually care about. Select that important text. Got it? Okay, now put your hemet on, 'cause this might blow your mind! Click the highlight icon on the Diigo toolbar. It's the one with the "T" on a page with a yellow highlighter. You will notice that the selected text gets a yellow background. This means that the text has been saved in your library, and as long as you have the Diigo add-on the text will be highlighted on the page! How's that for easy?
Now you've highlighted the text. It will appear in your library within the bookmark for the page it is on. Go to your library and you can see how it works. If you're not sure how to get to your library, just click the second icon on the toolbar (Diigo icon to the left of the search bar) and then select "My Library »".