Impala Public Jenkins has submitted this change and it was merged. ( http://gerrit.cloudera.org:8080/17008 )
Change subject: IMPALA-10463: Implement ds_theta_sketch() and ds_theta_estimate() functions ...................................................................... IMPALA-10463: Implement ds_theta_sketch() and ds_theta_estimate() functions These functions can be used to get cardinality estimates of data using Theta algorithm from Apache DataSketches. ds_theta_sketch() receives a dataset, e.g. a column from a table, and returns a serialized Theta sketch in string format. This can be written to a table or be fed directly to ds_theta_estimate() that returns the cardinality estimate for that sketch. Similar to the HLL sketch, the primary use-case for the Theta sketch is for counting distinct values as a stream, and then merging multiple sketches together for a total distinct count. For more details about Apache DataSketches' Theta see: https://datasketches.apache.org/docs/Theta/ThetaSketchFramework.html Testing: - Added some tests running estimates for small datasets where the amount of data is small enough to get the correct results. - Ran manual tests on tpch25_parquet.lineitem to compare perfomance with ds_hll_*. ds_theta_* is faster than ds_hll_* on the original data, the difference is around 1%-10%. ds_hll_estimate() is faster than ds_theta_estimate() on existing sketch. HLL and Theta gives closer estimate except for string. see IMPALA-10464. Change-Id: I14f24c16b815eec75cf90bb92c8b8b0363dcbfbc Reviewed-on: http://gerrit.cloudera.org:8080/17008 Reviewed-by: Impala Public Jenkins <[email protected]> Tested-by: Impala Public Jenkins <[email protected]> --- M be/src/exprs/aggregate-functions-ir.cc M be/src/exprs/aggregate-functions-test.cc M be/src/exprs/aggregate-functions.h M be/src/exprs/datasketches-functions-ir.cc M be/src/exprs/datasketches-functions.h M common/function-registry/impala_functions.py M fe/src/main/java/org/apache/impala/catalog/BuiltinsDb.java M testdata/data/README A testdata/data/theta_sketches_from_hive.parquet A testdata/workloads/functional-query/queries/QueryTest/datasketches-theta.test M tests/query_test/test_datasketches.py 11 files changed, 447 insertions(+), 0 deletions(-) Approvals: Impala Public Jenkins: Looks good to me, approved; Verified -- To view, visit http://gerrit.cloudera.org:8080/17008 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: merged Gerrit-Change-Id: I14f24c16b815eec75cf90bb92c8b8b0363dcbfbc Gerrit-Change-Number: 17008 Gerrit-PatchSet: 6 Gerrit-Owner: Fucun Chu <[email protected]> Gerrit-Reviewer: Fucun Chu <[email protected]> Gerrit-Reviewer: Gabor Kaszab <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
