Updating items in an index

[evvo1961]

My content (from a database) is read into an elasticsearch search index initially via a full index which stores the db record data into a class and then adds each class instance into the index that has been created.

My question is how would i do an incremental index...

i want to have a job run every set amount of time and any records it finds in the db that have been updated in that time i want them to be reindexed...

i cant just use the

client.Index(mycontent)

as the full index uses as this will add another copy of this record to the index...

can anyone advise how i just update a selected number of records already in the index from the amended db records that they correrspond to ?

thanks