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https://issues.apache.org/jira/browse/OAK-7897?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16689322#comment-16689322
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Thomas Mueller commented on OAK-7897:
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In theory, "UNION" might be faster than "IN" for a few (rare) cases, for
example:
{noformat}
SELECT [rep:facet(text)] FROM [nt:base] WHERE ([jcr:primaryType] = 'cqDam' OR
[jcr:primaryType] = 'cqPage') and ...
{noformat}
I'm not fully sure if there are other cases where UNION might be better.
What I think might be a problem, and I need to test this, is if there are many
many OR conditions, of the form
{noformat}
[name]='a' OR [name]='b' OR [name]='c' OR [name]='d' OR ...
{noformat}
Possibly we try out too many variants, so planning might be slow. A workaround
is to use "IN" in the query directly.
> Queries with OR simplified to IN shouldn't have alternative UNION query
> -----------------------------------------------------------------------
>
> Key: OAK-7897
> URL: https://issues.apache.org/jira/browse/OAK-7897
> Project: Jackrabbit Oak
> Issue Type: Sub-task
> Components: lucene
> Reporter: Vikas Saurabh
> Assignee: Thomas Mueller
> Priority: Minor
>
> Queries like {noformat} SELECT [rep:facet(text)] FROM [nt:base] WHERE [name]
> = 'Node1' OR [name] = 'Node2' {noformat} which would get simplified to {{IN}}
> clause still weigh in cost of alternative query with {{UNION}}. We should
> avoid that.
> /cc [~tmueller]
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