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  1. Calcite
  2. CALCITE-1578

Druid adapter: wrong semantics of topN query limit with granularity

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 1.11.0
    • Fix Version/s: 1.12.0
    • Component/s: druid
    • Labels:
      None

      Description

      Semantics of Druid topN query with limit and granularity is not equivalent to input SQL. In particular, limit is applied on each granularity value, not on the overall query.

      Currently, the following query will be transformed into a topN query:

      SELECT i_brand_id, floor_day(`__time`), max(ss_quantity), sum(ss_wholesale_cost) as s
      FROM store_sales_sold_time_subset
      GROUP BY i_brand_id, floor_day(`__time`)
      ORDER BY s DESC
      LIMIT 10;
      

      Previous query outputs at most 10 rows. In turn, the equivalent SQL query for a Druid topN query should be expressed as:

      SELECT rs.i_brand_id, rs.d, rs.m, rs.s
      FROM (
          SELECT i_brand_id, floor_day(`__time`) as d, max(ss_quantity) as m, sum(ss_wholesale_cost) as s,
                 ROW_NUMBER() OVER (PARTITION BY floor_day(`__time`) ORDER BY sum(ss_wholesale_cost) DESC ) AS rownum
          FROM store_sales_sold_time_subset
          GROUP BY i_brand_id, floor_day(`__time`)
      ) rs
      WHERE rownum <= 10;
      

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              • Assignee:
                julianhyde Julian Hyde
                Reporter:
                jcamachorodriguez Jesus Camacho Rodriguez
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                • Created:
                  Updated:
                  Resolved: