Creating a Partition allows you to improve search performance by searching over a smaller number of messages. After routing messages to a Partition, you can limit your search by using the Partition name in a search query.
For complete details, see Manage Partitions.
A Scheduled View reduces aggregate data down to the bare minimum, so they contain only the raw results that you need to generate your data. Queries that run against Scheduled Views return search results much faster because the data is pre-aggregated before the query is run. And a Scheduled View query runs continuously, once per minute.
For complete details, see Manage Scheduled Views.
With Multi-retention, you can create Partitions and Scheduled Views to store your data as needed, and set different retention periods for those Partitions and Scheduled Views. This way, you can keep the data you need for as long as you need it, while other less important data can be retained for a shorter period, reducing your overall cost of operation.
For details, see Manage Indexes with Multi-retention.