[DRILL-4573] Zero copy LIKE, REGEXP_MATCHES, SUBSTR

• Type: Improvement
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.7.0
• Assignee: Unassigned
• Reporter: jean-claude
• Created: 02/Apr/16 02:37
• Updated: 09/Jan/18 19:52
• Resolved: 16/Jun/16 03:40

Description

All the functions using the java.util.regex.Matcher are currently creating Java string objects to pass into the matcher.reset().

However this creates unnecessary copy of the bytes and a Java string object.

The matcher uses a CharSequence, so instead of making a copy we can create an adapter from the DrillBuffer to the CharSequence interface.

Gains of 25% in execution speed are possible when going over VARCHAR of 36 chars. The gain will be proportional to the size of the VARCHAR.

Issue Links

• is related to: DRILL-4645 Regex_replace() function is broken
• is related to: DRILL-4688 String functions may produce incorrect result when input has multi-byte character
• links to: GitHub Pull Request #458
• links to: GitHub Pull Request #502
• links to: GitHub Pull Request #512