Contents

• GROUP BY aggregate on JOIN
  • Query Info (statistics from 100k dataset; larger datasets may have different values):
  • Comparison Strategy

GROUP BY aggregate on JOIN

• Join: stackoverflow_posts → comments
• Description: Grouped aggregate (COUNT, SUM) with GROUP BY on a low-cardinality dimension (post_type_id). Sorted by sub-aggregation metric (SUM). Exercises the DataFusion backend’s grouped aggregate pipeline including custom_scan_tlist for scanrelid=0.

Query Info (statistics from 100k dataset; larger datasets may have different values):

• ‘code’ selectivity on stackoverflow_posts.body: ~75%

Comparison Strategy

Native PostgreSQL aggregation atop GIN indexes is omitted as it is unworkably slow on large datasets. ParadeDB also executes this query faster than PostgreSQL using the columnar base scan (paradedb.enable_aggregate_custom_scan = off), but redundant basescan.sql variants were pruned from the suite to keep execution fast.