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jean-claude edited comment on DRILL-4573 at 4/10/16 6:49 PM: ------------------------------------------------------------- Reduction 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. You can test the performance gain by creating a simple csv file with one column containing UUID like this {code:borderStyle=solid}for i in {1..1000000}; do uuidgen; done > /Users/jccote/test.csv{code} then query using drill {code:sql|borderStyle=solid}select count(1) from dfs.`/Users/jccote/test.csv` where columns[0] like '0%';{code} run it multiple times to get a good estimate was (Author: jccote): 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. You can test the performance gain by creating a simple csv file with one column containing UUID like this {code:borderStyle=solid}for i in {1..1000000}; do uuidgen; done > /Users/jccote/test.csv{code} then query using drill {code:sql|borderStyle=solid}select count(1) from dfs.`/Users/jccote/test.csv` where columns[0] like '0%';{code} run it multiple times to get a good estimate > Zero copy LIKE, REGEXP_MATCHES, SUBSTR > -------------------------------------- > > Key: DRILL-4573 > URL: https://issues.apache.org/jira/browse/DRILL-4573 > Project: Apache Drill > Issue Type: Improvement > Reporter: jean-claude > Priority: Minor > Attachments: DRILL-4573.patch.txt > > > 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)