Hi pavanae, the docs here have more information on summary indexing in general : http://docs.splunk.com/Documentation/Splunk/6.5.2/Knowledge/Usesummaryindexing
Concerning the sourcetype, all data that is summary indexed gets the
stash sourcetype. The original sourcetype is preserved in the
orig_sourcetype fields, and so you could figure out what sourcetypes are being put into summary indexes by running:
sourcetype=stash | stats count by orig_sourcetype
Please let me know if this answers your question!