Isolating a Query Partition
By default, when a search query is given to MarkLogic, all query partitions are searched, regardless of the query assignment policy set on the partition. To avoid this overhead, you can use the tieredstorage:partition-set-exclusion-enabled function to set safe-to-exclude on the query partition so that it will not be searched if the search query does not match the query assignment policy set for that partition.
When documents are distributed in query partitions based on time and date, you may want the option to always search a particular tier (typically the tier holding the most recent documents) because it may be the case that some of the documents in that tier are about to be migrated to a different tier but have not yet been moved. So if a search only matches the query set in a “lower” tier, the non-matching “higher” tier will also be searched to locate the matching documents that have not yet moved to the lower tier.
For example, you have two query partitions that hold the documents, “Seafood Daily,” as shown below. The query assignment policy for each compares the date of the document with the current date and sorts the documents so that one partition contains the issues from the current year and the other archives the issues from previous years. The query partition serving as the archive is set to safe-to-exclude and the query partition containing this year’s issues is not set with this option.
The current year is 2016 and a search query is given that matches the query for Archive Partition will also result in a search on Current Year Partition. However, a search query that matches the Current Year Partition will exclude the Archive Partition.
