Hi Sridhar,
We can also use External match functionality to check if the record is exists or not based on the attribute values configured. If it matches the external data with Reltio, then it will return MDM Id, else it will return null. You can extract non-match records and post to Reltio. This will be used for batch process. For real time process, then you can use SearchBeforeCreate as per @Robert.
"https://docs.reltio.com/en/model/consolidate-data/configure-match-rules-overview/external-match"
"https://docs.reltio.com/en/explore/get-going-with-apis-and-rocs-utilities/reltio-rest-apis/model-apis/entities-api/search-before-create"
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Nagaraju
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