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Re: Pcache overlay bug or undocumented "feature"?

Daniel Montero Motilla wrote:
Hi, I'm obtaining a strange (almost for me) behaviour with pcache
overlay (openldap 2.3.27), I have a configuration similar to this one:

proxyattrset 0 uid cn sn mail description
proxyattrset 1 cn description
proxytemplate (&(objectClass=)(uid=)) 0 3600
proxytemplate (&(objectClass=)(cn=)) 1 3600

With this configuration, I perform this search:

(&(objectClass=groupOfNames)(cn=mygroup)) cn description


Digging on pcache.c, I see that the problem is that 'get_attr_set'
function doesn't look for a proxyattrset that _exactly_ matches with
my search attribute set, it instead looks for a proxyattrset that is a
_superset_ of the search attribute set.

Yes, that's a recent change. I guess we call it an undocumented feature, please file an ITS against the documentation.

On my example, my search attribute set (cn, description) is a subset of proxyattrset '0', so 'get_attr_set' returns '0'. Then, the application looks for a proxytemplate whose proxyattrset equals the one obtained with 'get_attr_set' (0), so it obtains the template '(&(objectClass=)(uid=))' and compares it with my search template '(&(objectClass=)(cn=))', so I get 'NOT CACHEABLE'.

As a workaround I have inverted the proxyattrset index numbers so
'get_attr_set' finds first the most specific proxyattrset, but i'm
curious about if this behaviour is the intended one or if I should
fill an ITS with a patch (the change in code would be minimal), what
do you think?

No, just delete the other proxyattrset directive, you don't need it at all.

  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP     http://www.openldap.org/project/