[SOLR-10436] Add hashRollup Streaming Expression

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Resolved
• Fix Version/s: 8.1
• Assignee: Joel Bernstein
• Reporter: Joel Bernstein
• Created: 06/Apr/17 15:16
• Updated: 08/Jun/19 15:24
• Resolved: 28/Feb/19 14:34

Description

The hashRollup Streaming Expression performs group by aggregations by keeping all the groups in an in-memory HashMap. The existing rollup expression requires that the tuples be sorted by the group by fields. The hashRollup will not have the sorting requirement, but it will also not have support for unlimited cardinality, like the rollup expression.

The hashRollup or rollup can then be chosen based on the requirements of the query.