[
https://issues.apache.org/jira/browse/CALCITE-7906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18134466#comment-18134466
]
Julian Hyde commented on CALCITE-7906:
--------------------------------------
Can you give one or two examples in the description of a LIKE pattern, the
regex we used to translate to, and the new regex?
Can you add one Quidem test? I'm guessing that it's possible to write a query
like 'select * from emp where ename like '%J%E%S%' that is very slow if this
bug has not been fixed.
> LikePattern matching time grows exponentially with the number of '%' wildcards
> ------------------------------------------------------------------------------
>
> Key: CALCITE-7906
> URL: https://issues.apache.org/jira/browse/CALCITE-7906
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Ruben Q L
> Assignee: Ruben Q L
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.43.0
>
>
> LikePattern.likeToRegex turns each % into .* and matches with
> java.util.regex. A pattern with many wildcards makes the regex engine
> backtrack heavily when the name doesn't match.
--
This message was sent by Atlassian Jira
(v10.3.26#10030026)
