8:50 a.m.
Hi there:
I'm trying to understand how ldap filters work. Based on this simple
logic expression:
EXPR_1 (or) EXPR_2
if EXPR1 returns TRUE, will slapd still try to evaluate EXPR2? or will
slapd evaluate EXPR2 anyway even if EXPR_1 is true?
I think that while the ldap filter is bigger then performance is worse,
right?
could somebody explain me a little about this logic of evaluation in
ldap filters?
Thanks
9:10 a.m.
Jason Voorhees wrote:
Hi there:
I'm trying to understand how ldap filters work. Based on this simple
logic expression:
EXPR_1 (or) EXPR_2
if EXPR1 returns TRUE, will slapd still try to evaluate EXPR2? or will
slapd evaluate EXPR2 anyway even if EXPR_1 is true?
I think that while the ldap filter is bigger then performance is worse,
right?
could somebody explain me a little about this logic of evaluation in
ldap filters?
As far as I understand the code, test_filter() stops filtering,
returning success, at the first occurrence of TRUE.
p.
Ing. Pierangelo Masarati
OpenLDAP Core Team
SysNet s.r.l.
via Dossi, 8 - 27100 Pavia - ITALIA
http://www.sys-net.it
-----------------------------------
Office: +39 02 23998309
Mobile: +39 333 4963172
Fax: +39 0382 476497
Email: ando(a)sys-net.it
-----------------------------------
9:14 a.m.
Thanks. That allows me to build complex filters using OR logic without
being worried about performance.
Thanks again, bytes!
Pierangelo Masarati escribió:
Jason Voorhees wrote:
> Hi there:
>
> I'm trying to understand how ldap filters work. Based on this simple
> logic expression:
>
> EXPR_1 (or) EXPR_2
>
> if EXPR1 returns TRUE, will slapd still try to evaluate EXPR2? or will
> slapd evaluate EXPR2 anyway even if EXPR_1 is true?
>
> I think that while the ldap filter is bigger then performance is worse,
> right?
>
> could somebody explain me a little about this logic of evaluation in
> ldap filters?
As far as I understand the code, test_filter() stops filtering,
returning success, at the first occurrence of TRUE.
p.
Ing. Pierangelo Masarati
OpenLDAP Core Team
SysNet s.r.l.
via Dossi, 8 - 27100 Pavia - ITALIA
http://www.sys-net.it
-----------------------------------
Office: +39 02 23998309
Mobile: +39 333 4963172
Fax: +39 0382 476497
Email: ando(a)sys-net.it
-----------------------------------
9:21 a.m.
Jason Voorhees wrote:
Thanks. That allows me to build complex filters using OR logic
without
being worried about performance.
of course, if you build a complex filter with a long list of OR-ed AVAs,
all the indexed ones will be considered when listing candidates.
p.
Ing. Pierangelo Masarati
OpenLDAP Core Team
SysNet s.r.l.
via Dossi, 8 - 27100 Pavia - ITALIA
http://www.sys-net.it
-----------------------------------
Office: +39 02 23998309
Mobile: +39 333 4963172
Fax: +39 0382 476497
Email: ando(a)sys-net.it
-----------------------------------
9:39 a.m.
Jason Voorhees writes:
Thanks. That allows me to build complex filters using OR logic
without
being worried about performance.
Sorry, no. First slapd must locate all entries to compare with the
filter. For that it uses indexes. First it uses the DN index, to find
just the entry IDs of just entries in the search scope.
Then if all the ORed components are indexed, it can narrow this list
further down by only checking entries that match one of the filter
components. OTOH if one of the ORed components is not indexed, slapd
cannot narrow down the entry candidate list further.
Finally it checks each candidate entry against the filter. When
checking an entry, slapd can indeed stop the first time an OR yields
TRUE. Or the first time an AND yields not-TRUE (FALSE or Undefined).
--
Hallvard
9:57 a.m.
mmm, I'm planning to build something like this in /etc/saslauthd.conf:
(&(mail=%U@%d)(|(&(objectClass=VirtualMailaccount)(accountActive=TRUE))(objectClass=VirtualMailAlias)))
that tries to locate two kind of entries:
1. mail=user@domain,vd=domain,o=hosting,dc=myldap,dc=com
(VirtualMailAccount)
2. cn=postmaster,vd=domain,o=hosting,dc=myldap,dc=com
(VirtualMailAlias)
There could be hundreds or maybe thousand of entries of type (1), but
only 1 entry of type (2).
The filter shown above is used to authenticate users trough saslauthd.
So 95% of times users authenticate using type (1), but sometimes I would
need to authenticate as 'postmaster' using type (2).
I was worried about performance because using
(objectClass=VirtualMailAlias) with OR just for a unique account in my
domain.
Would I get much better performance if remove
(objectClass=VirtualMailAlias) from the filter?
Do you believe that the performance impact will be big?
Hallvard B Furuseth escribió:
Jason Voorhees writes:
> Thanks. That allows me to build complex filters using OR logic without
> being worried about performance.
Sorry, no. First slapd must locate all entries to compare with the
filter. For that it uses indexes. First it uses the DN index, to find
just the entry IDs of just entries in the search scope.
Then if all the ORed components are indexed, it can narrow this list
further down by only checking entries that match one of the filter
components. OTOH if one of the ORed components is not indexed, slapd
cannot narrow down the entry candidate list further.
Finally it checks each candidate entry against the filter. When
checking an entry, slapd can indeed stop the first time an OR yields
TRUE. Or the first time an AND yields not-TRUE (FALSE or Undefined).
10:14 a.m.
Jason Voorhees writes:
mmm, I'm planning to build something like this in
/etc/saslauthd.conf:
(&(mail=%U@%d)(|(&(objectClass=VirtualMailaccount)(accountActive=TRUE))(objectClass=VirtualMailAlias)))
I don't know saslauthd, but: Will (mail=%U@%d) match at most one entry?
Then if you have an 'eq' index for 'mail', slapd won't need to
compare
more than one entry with the filter. Since the 'or' filter is inside
the 'and', it won't be a problem in this repect.
that tries to locate two kind of entries:
1. mail=user@domain,vd=domain,o=hosting,dc=myldap,dc=com
(VirtualMailAccount)
If you do a baseobject search at that baseDN, that's also just
one entry to examine.
2. cn=postmaster,vd=domain,o=hosting,dc=myldap,dc=com
(VirtualMailAlias)
There could be hundreds or maybe thousand of entries of type (1), but
only 1 entry of type (2).
If mail is indexed, that's fine.
The filter shown above is used to authenticate users trough
saslauthd.
So 95% of times users authenticate using type (1), but sometimes I would
need to authenticate as 'postmaster' using type (2).
I was worried about performance because using
(objectClass=VirtualMailAlias) with OR just for a unique account in my
domain.
Would I get much better performance if remove
(objectClass=VirtualMailAlias) from the filter?
Do you believe that the performance impact will be big?
No, not much.
--
Hallvard
10:45 a.m.
Hallvard B Furuseth escribió:
Jason Voorhees writes:
> mmm, I'm planning to build something like this in /etc/saslauthd.conf:
>
>
(&(mail=%U@%d)(|(&(objectClass=VirtualMailaccount)(accountActive=TRUE))(objectClass=VirtualMailAlias)))
I don't know saslauthd, but: Will (mail=%U@%d) match at most one entry?
Yes, it always match only one entry per search operation.
Then if you have an 'eq' index for 'mail', slapd
won't need to compare
more than one entry with the filter. Since the 'or' filter is inside
the 'and', it won't be a problem in this repect.
Yes, I mantain 'eq' index for 'mail' atttributes.
> that tries to locate two kind of entries:
>
> 1. mail=user@domain,vd=domain,o=hosting,dc=myldap,dc=com
> (VirtualMailAccount)
If you do a baseobject search at that baseDN, that's also just
one entry to examine.
> 2. cn=postmaster,vd=domain,o=hosting,dc=myldap,dc=com
> (VirtualMailAlias)
>
> There could be hundreds or maybe thousand of entries of type (1), but
> only 1 entry of type (2).
If mail is indexed, that's fine.
> The filter shown above is used to authenticate users trough saslauthd.
> So 95% of times users authenticate using type (1), but sometimes I would
> need to authenticate as 'postmaster' using type (2).
>
> I was worried about performance because using
> (objectClass=VirtualMailAlias) with OR just for a unique account in my
> domain.
>
> Would I get much better performance if remove
> (objectClass=VirtualMailAlias) from the filter?
> Do you believe that the performance impact will be big?
No, not much.
Thanks a lot Hallvard, bytes! :)
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7 comments
3 participants
participants (3)
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Hallvard B Furuseth -
Jason Voorhees -
Pierangelo Masarati