A merge policy determines how frequently the Dgraph merges incremental update generations in its index files, for a specific data domain.
A version is persisted as a sequence of generation files. A new version appends a new generation file to the sequence. Query latency depends, in part, on the number and size of generation files used to store the index files.
Generation files are combined through a process called merging. Merging is a background task that does not affect the Endeca data domain processing, but may affect its performance. Because of this, you can set a merge policy that dictates the aggressiveness of the merges. In a clustered environment, a request to set the merge policy is routed to the leader Dgraph node.