What is the Oracle UCM database design?The best available info on data model is here: http://docs.oracle.com/cd/E10316_01/cs/cs_doc_10/documentation/admin/troubleshooting_10en.pdf (chapter Appendix A.)
Where is the metadata info stored in UCM? And What are the columns in meta data table?Standard metadata is in Revisions, custom ones in DocMeta
How are security groups and metadata related?Security group is one of metadata fields in the Revisions
How can i find which meta data is used in which Profile or security groups?A security group is a metadata of an item, and unless the system implements some custom logic, there is no relation between SG and other metadata.