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From "Gabor Kaszab (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-9633: Implement ds hll union()
Date Tue, 07 Jul 2020 15:02:03 GMT
Hello Csaba Ringhofer, Impala Public Jenkins, 

I'd like you to reexamine a change. Please visit

to look at the new patch set (#3).

Change subject: IMPALA-9633: Implement ds_hll_union()

IMPALA-9633: Implement ds_hll_union()

This function receives a set of sketches produced by ds_hll_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.:
  FROM sketch_tbl
  WHERE partition_col=1 OR partition_col=5;

  - Apart from the automated tests I added to this patch I also
    tested ds_hll_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_hll_union() on those sketches.

Change-Id: I67cdbf6f3ebdb1296fea38465a15642bc9612d09
M be/src/exprs/CMakeLists.txt
M be/src/exprs/
M be/src/exprs/aggregate-functions.h
A be/src/exprs/
A be/src/exprs/datasketches-common.h
M be/src/exprs/
M fe/src/main/java/org/apache/impala/catalog/
M testdata/workloads/functional-query/queries/QueryTest/datasketches-hll.test
8 files changed, 232 insertions(+), 29 deletions(-)

  git pull ssh:// refs/changes/95/16095/3
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I67cdbf6f3ebdb1296fea38465a15642bc9612d09
Gerrit-Change-Number: 16095
Gerrit-PatchSet: 3
Gerrit-Owner: Gabor Kaszab <>
Gerrit-Reviewer: Csaba Ringhofer <>
Gerrit-Reviewer: Gabor Kaszab <>
Gerrit-Reviewer: Impala Public Jenkins <>

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