Paging LDAP query [DATALDAP-30]

[spring-projects-issues]

Houcheng opened DATALDAP-30 and commented

We required a paging repository to query the LDAP database in paged

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Issue Links:

• DATALDAP-138 Handle large find all requests
  ("is duplicated by")

Referenced from: pull request #3

[spring-projects-issues]

Mark Paluch commented

See https://github.com/spring-projects/spring-data-ldap/tree/issue/DATALDAP-30

[spring-projects-issues]

Mark Paluch commented

LDAP paging relies on a continuation cookie that is returned from the previous LDAP query. This cookie is only valid for the same connection. LdapTemplate always closes the connection except for transactional use. When using transactions ContextSourceTransactionManager sticks to the same connection so effectively LDAP paging on repository level would only work with transactions enabled and the user is required to provide an outer transaction.

Requiring transactions for paging isn't something you'd expect from repositories. I'm inclined to not implement paging and rather investigate whether we can provide streaming support for LDAP.

See also: http://docs.spring.io/spring-ldap/docs/2.0.2.RELEASE/reference/#paged-search-results

Houcheng what was your motivation to use LDAP paging?

[spring-projects-issues]

Houcheng commented

Got it. The pagination request must be created in the context of a transaction, then the LDAP template will keep the connection until all paged retrieved. This seems the limitation of LdapTemplate and maybe could be enhanced, as most of the server's page cookie is not bound to the connection.

I have a software that uses LDAP query to understand the OU and permission of the company. Some company may have a very flat organization and one query may get hundred of results. Query without pagination will have a long response time and I worry that it would cause the timeout in Production.

[spring-projects-issues]

Mark Paluch commented

Thanks for your fast response. I'm not convinced adding paging support to LdapRepository is a good idea right now. The conditions that are required to make LDAP paging work are restrictive in terms of transactions or depend a lot on the LDAP server details. It's not obvious from an API perspective that paging comes with this kind of limitations. I will close this ticket with "Won't fix" for now.

Using LdapTemplate with PagedResultsDirContextProcessor allows paging for now. Once we either figure out a way how to make paging work without imposing too many constraints, we might come back to this ticket