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https://issues.apache.org/jira/browse/HADOOP-12782?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15150655#comment-15150655
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Wei-Chiu Chuang commented on HADOOP-12782:
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Hi [~drankye] thanks for the review and suggestion. Really appreciate!
I am not sure if other LDAP providers have attributes to do the similar
optimization. I read a few Active Directory books and did some experiments to
make sure this is supported in AD. What confused me initially was that there
does not seem to be one protocol for using LDAP for authentication by all LDAP
servers.
I think your suggestion makes sense to me. I'll update my patch with your
suggestion, and I'll also look for similar optimization for other LDAP
providers.
Thanks again.
> Faster LDAP group name resolution with ActiveDirectory
> ------------------------------------------------------
>
> Key: HADOOP-12782
> URL: https://issues.apache.org/jira/browse/HADOOP-12782
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Wei-Chiu Chuang
> Assignee: Wei-Chiu Chuang
> Attachments: HADOOP-12782.001.patch, HADOOP-12782.002.patch
>
>
> The typical LDAP group name resolution works well under typical scenarios.
> However, we have seen cases where a user is mapped to many groups (in an
> extreme case, a user is mapped to more than 100 groups). The way it's being
> implemented now makes this case super slow resolving groups from
> ActiveDirectory.
> The current LDAP group resolution implementation sends two queries to a
> ActiveDirectory server. The first query returns a user object, which contains
> DN (distinguished name). The second query looks for groups where the user DN
> is a member. If a user is mapped to many groups, the second query returns all
> group objects associated with the user, and is thus very slow.
> After studying a user object in ActiveDirectory, I found a user object
> actually contains a "memberOf" field, which is the DN of all group objects
> where the user belongs to. Assuming that an organization has no recursive
> group relation (that is, a user A is a member of group G1, and group G1 is a
> member of group G2), we can use this properties to avoid the second query,
> which can potentially run very slow.
> I propose that we add a configuration to only enable this feature for users
> who want to reduce group resolution time and who does not have recursive
> groups, so that existing behavior will not be broken.
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