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impala/testdata/workloads/functional-query/queries/QueryTest
Gabor Kaszab 033a4607e2 IMPALA-9959: Implement ds_kll_sketch() and ds_kll_quantile() functions
ds_kll_sketch() is an aggregate function that receives a float
parameter (e.g. a float column of a table) and returns a serialized
Apache DataSketches KLL sketch of the input data set wrapped into
STRING type. This sketch can be saved into a table or view and later
used for quantile approximations. ds_kll_quantile() receives two
parameters: a STRING parameter that contains a serialized KLL sketch
and a DOUBLE that represents the rank of the quantile in the range of
[0,1]. E.g. rank=0.1 means the approximate value in the sketch where
10% of the sketched items are less than or equals to this value.

Testing:
  - Added automated tests on small data sets to check the basic
    functionality of sketching and getting a quantile approximate.
  - Tested on TPCH25_parquet.lineitem to check that sketching and
    approximating works on bigger scale as well where serialize/merge
    phases are also required. On this scale the error range of the
    quantile approximation is within 1-1.5%

Change-Id: I11de5fe10bb5d0dd42fb4ee45c4f21cb31963e52
Reviewed-on: http://gerrit.cloudera.org:8080/16235
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
2020-07-31 14:34:49 +00:00
..
2014-06-20 13:35:10 -07:00