Package com.apple.foundationdb.record.query.plan.temp.rules

Class PushSortIntoExistingIndexRule

  • @API(EXPERIMENTAL)
public class PushSortIntoExistingIndexRule
extends PlannerRule<LogicalSortExpression>
    A rule that pushes a sort into a compatibly-ordered index scan, including one with existing comparisons (from filters or other sort orders) that might affect whether the index is compatibly ordered. 
     
       +-----------------------------+                 +---------------------------+
       |                             |                 |                           |
       |  LogicalSortExpression      |                 |  LogicalSortExpression    |
       |            prefix, suffix   |                 |                 suffix    |
       |                             |                 |                           |
       +-------------+---------------+                 +-------------+-------------+
                     |                     +------>                  |
                     | qun                                           | newQun
                     |                                               |
     +---------------+------------------+            +---------------+------------------+
     |                                  |            |                                  |
     |  IndexEntrySourceScanExpression  |            |  IndexEntrySourceScanExpression  |
     |                           orders |            |                     order|prefix |
     |                                  |            |                                  |
     +----------------------------------+            +----------------------------------+
    or if there are no other predicates 
     
       +-----------------------------+               +----------------------------------+
       |                             |               |                                  |
       |    LogicalSortExpression    |     +------>  |  IndexEntrySourceScanExpression  |
       |                     prefix  |               |                           orders |
       |                             |               |                                  |
       +-------------+---------------+               +----------------------------------+
                     |
                     | qun
                     |
     +---------------+------------------+
     |                                  |
     |  IndexEntrySourceScanExpression  |
     |                          orders  |
     |                                  |
     +----------------------------------+