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https://issues.apache.org/jira/browse/CALCITE-7906?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ruben Q L resolved CALCITE-7906.
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    Resolution: Fixed

Done via 
[{{4f8ad6c}}|https://github.com/apache/calcite/commit/4f8ad6c3133a215621de0cb411c80d34cc8a2778]

> Improve LikePattern to support '_' wildcard and enhance the performance of 
> '%' wildcard
> ---------------------------------------------------------------------------------------
>
>                 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 (which handles the patterns passed to JDBC {{DatabaseMetaData}} 
> methods such as {{getTables}} and {{getColumns}} and to {{Lookup.getNames}}) 
> has implements matching via {{likeToRegex}} which turns each % into .* and 
> matches with java.util.regex. For example:
> {noformat}
> %%%%%%%%%%x  =>  .*.*.*.*.*.*.*.*.*.*x
> %a%a%a%a%a%a%a%a%a%a%x  =>  .*a.*a.*a.*a.*a.*a.*a.*a.*a.*a.*x
> {noformat}
> A pattern with many wildcards makes the regex engine backtrack heavily when 
> the name doesn't match.
> Apart from that, it currently does not support '_' wildcard, as JDBC 
> specification requires.



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