Files
impala/testdata/workloads/functional-query/queries/QueryTest
Gabor Kaszab f95f7940e4 IMPALA-10017: Implement ds_kll_union() function
This function receives a set of serialized Apache DataSketches KLL
sketches produced by ds_kll_sketch() and merges them into a single
sketch.

An example usage is to create a sketch for each partition of a table,
write these sketches to a separate table and based on which partition
the user is interested of the relevant sketches can be union-ed
together to get an estimate. E.g.:
  SELECT
      ds_kll_quantile(ds_kll_union(sketch_col), 0.5)
  FROM sketch_tbl
  WHERE partition_col=1 OR partition_col=5;

Testing:
  - Apart from the automated tests I added to this patch I also
    tested ds_kll_union() on a bigger dataset to check that
    serialization, deserialization and merging steps work well. I
    took TPCH25.linelitem, created a number of sketches with grouping
    by l_shipdate and called ds_kll_union() on those sketches.

Change-Id: I020aea28d36f9b6ef9fb57c08411f2170f5c24bf
Reviewed-on: http://gerrit.cloudera.org:8080/16267
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
2020-08-08 11:50:04 +00:00
..
2014-06-20 13:35:10 -07:00