I was working on a SharePoint 2010 site which was build on Team Site Template. I was not able to find the Doument Ids for the document uploaded into the Document Library in this site. Even the Document ID column was not appearing in the document libarary. On further investigation I found that we need to enable the Document ID Feature to use the Document ID's in the library. If we use a Document Center template to create a site collection the Document ID feature is enabled by default. To enable Document ID feature go to Site Actions --> Site Settings --> Under Site Collection Administration --> Site Collection Feature
Now the question is how to get the Document Id's for these existing documents. On some investigation I found there are 2 jobs which runs on a daily basis. These job are
1. Document ID enable/disable job: Work item that propagates content type changes across all sites when the Document ID feature is reconfigured.
2. Document ID assignment job: Work item that assigns Document ID to all items in the site collection.
Now I executed Document ID assignment Job from the Central Admin and my all the documents in the Document Library got a Document ID :)
There is also another feature with Document ID that we can change the characters in the Document ID. To do this go to Site Actions --> Site Settings --> Under Site Collection Administration --> Document ID Settings
I have modified the string here to start with ABCD and all my new documents are getting the Document ID starting with ABCD: