[SOLR-10918] Hashing for IntPointFields is broken for HLL

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: main (10.0), 9.2
• Labels: numeric-tries-to-points
• Assignee: Houston Putman
• Reporter: Chris M. Hostetter
• Created: 19/Jun/17 21:26
• Updated: 27/Mar/23 18:04
• Resolved: 26/Oct/22 22:06

Description

discovered as part of SOLR-10807...

when using Points based numerics, the HLL estimates using the raw values vs the hashed values disagree slightly – this suggests some possible bug (or the very least: room for optimization) when using Points fields.

Example from SOLR-10807 when swaping IntPointField in place of TrieIntField...

   [junit4]   2> NOTE: reproduce with: ant test  -Dtestcase=TestDistributedStatsComponentCardinality -Dtests.method=test -Dtests.seed=63854996088ED7B7 -Dtests.slow=true -Dtests.locale=de-GR -Dtests.timezone=Etc/UCT -Dtests.asserts=true -Dtests.file.encoding=ISO-8859-1
   [junit4] FAILURE 13.3s J2 | TestDistributedStatsComponentCardinality.test <<<
   [junit4]    > Throwable #1: java.lang.AssertionError: int_i: hashed vs prehashed, real=7260, p=q=id:[1186+TO+8445]&rows=0&stats=true&stats.field={!cardinality%3Dtrue+hllLog2m%3D7+hllRegwidth%3D8}int_i&stats.field={!cardinality%3Dtrue+hllLog2m%3D7+hllRegwidth%3D8+hllPreHashed%3Dtrue}int_i_prehashed_l&stats.field={!cardinality%3Dtrue+hllLog2m%3D7+hllRegwidth%3D8}long_l&stats.field={!cardinality%3Dtrue+hllLog2m%3D7+hllRegwidth%3D8+hllPreHashed%3Dtrue}long_l_prehashed_l&stats.field={!cardinality%3Dtrue+hllLog2m%3D7+hllRegwidth%3D8}string_s&stats.field={!cardinality%3Dtrue+hllLog2m%3D7+hllRegwidth%3D8+hllPreHashed%3Dtrue}string_s_prehashed_l expected:<6632> but was:<7929>
   [junit4]    >        at __randomizedtesting.SeedInfo.seed([63854996088ED7B7:EBD1764CA672BA4F]:0)
   [junit4]    >        at org.apache.solr.handler.component.TestDistributedStatsComponentCardinality.test(TestDistributedStatsComponentCardinality.java:149)

Issue Links

• is duplicated by: SOLR-7802 TestDistributedStatsComponentCardinality failure
• relates to: SOLR-10807 Randomize PointFields in all tests unless explicit reason not to
• links to: GitHub Pull Request #1137