[HIVE-18487] Vectorization: Undecoded utf-8 fast-path for _ wildcards in LIKE

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.0.0
• Assignee: Unassigned
• Reporter: Gopal Vijayaraghavan
• Created: 18/Jan/18 19:05
• Updated: 18/Jan/18 21:47

Description

Queries with "%" are optimized using the BoyerMooreHorspool lookups, while the simpler single char wildcard "_" isn't optimized to be faster.

https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/AbstractFilterStringColLikeStringScalar.java

Has Begin, End, Middle and Chained checkers for "%", but no option to handle "_" in the chained mode.