dynamobi/dynamobi — Issue #191: [LDB-130] change LcsIndexSemiJoinRule to use LhxAggRel for duplicate key removal
Author: dynamobi-build
Created: 2011-12-30 02:20:33+00:00
State: open
Labels: LCS, LDB

[reporter="jvs", created="Sat, 26 Aug 2006 22:09:42 -0500 (GMT-05:00)"]
Currently we construct a FennelSortRel with discardDuplicates=true. Now that we have hash agg, should instead use that to remove duplicates, and put a non-distinct FennelSortRel on top (so that we'll still visit the foreign key index in order).

(FennelSortRel with discardDuplicates=true gets implemented via the temp btree insertion sort mechanism, which will be very slow for large sets.)

You could instantiate an LhxAggRel directly, but it would be cleaner to make a logical AggregateRel and let