Boaz Ben-Zvi created DRILL-6881: ----------------------------------- Summary: Hash-Table insert and probe: Compare hash values before keys Key: DRILL-6881 URL: https://issues.apache.org/jira/browse/DRILL-6881 Project: Apache Drill Issue Type: Improvement Components: Execution - Relational Operators Affects Versions: 1.14.0 Reporter: Boaz Ben-Zvi Assignee: Boaz Ben-Zvi Fix For: 1.16.0
When checking for existence of a key in the hash table (during _put_ or _probe_ operations), the value of that key is compared (using generated code) with a potential match key (same bucket). This comparison is slightly expensive (e.g., long keys, multi column keys, checking null conditions, NaN, etc). Instead, if the hash-values of the two keys are compared first (at practically zero cost), then the costly comparison can be avoided in case the hash values don't match. This code change is trivial, and given that the relevant Hash-Table code is *hot code*, then even minute improvements could add up. -- This message was sent by Atlassian JIRA (v7.6.3#76005)