Monday, March 13, 2023

[389-users] Re: 2.x query performance problem

Hello Thierry,
 
yes, index on 'uniqueMember' is 'eq'.
I tested ldapsearch with the option 'manageDSAit' and got strage results.
On 1.4.x nothing changed with oder without this option: 0,0x sec
 
With 2.0.x with this option the search takes half the time as without this option.
query without option direcly after import: 7s
query with option directly after import: 3,5s
 
after reindexing (dsctl db2index)
query without option: 2s
query With option. 0,9s
 
 
next I will try to set breakpoint for slapi_vattr_filter_test,
 
regards Claas
 
 
Gesendet: Freitag, 10. März 2023 um 15:59 Uhr
Von: "Thierry Bordaz" <tbordaz@redhat.com>
An: 389-users@lists.fedoraproject.org
Betreff: [389-users] Re: 2.x query performance problem

Hi Class,

pstack is a gdb wrapper command to dump backtrace of all threads. installing gdb you may get it.

I suspect that the culprit could be the evaluation of the filter over the matching entries (~500 groups owning cn=sampleuser). Using ldapsearch could you reproduce with '-e manageDSAit' option and check if there is still a diff between 1.4.4 and 2.0.
Another investigation is to put a breakpoint on slapi_vattr_filter_test. With such filter it should not be called.

Just for confirmation, you indexed 'uniqueMember' did you indexed in 'eq' ?

best regards
thierry

On 3/10/23 14:47, Claas Vieler wrote:
Hello Thierry,
 
I can confirm index on 'uniqueMember' for both versions. I also tried to recreate and reindex 'uniqueMember', same result.
SRCH-records are inconspicuous, except high optime (no notes..)
 
What exactly do you want to see in pstacks. Do you mean the output from pstack-tool?
 
regards
Claas
Gesendet: Dienstag, 07. März 2023 um 15:38 Uhr
Von: "Thierry Bordaz" <tbordaz@redhat.com>
An: 389-users@lists.fedoraproject.org
Betreff: [389-users] Re: 2.x query performance problem

Hi Claas,

I do not recall a specific change 1.4.4 vs 2.0 that could explain this.

Do you confirm that 'uniqueMember' is indexed in equality on both ? What are the SRCH records in the access logs (notes=A ?).
On 2.0, it lasts 2sec, you may try to capture few pstacks that would give some tips.

regards
thierry

On 3/7/23 14:54, Claas Vieler wrote:
Hello,
 
we have a search performance problem when we migrated from 1.4.4.19 to 2.0.17.
 
Our environment has about 100k entries, about 15k users and about 10k groups. Also big groups with thousand of users, also users with thousand of group membership. So I would call it a small instance
 
On 1.4.x query perfomance ist fine:
ldapsearch for "(uniqueMember=cn=sampleuser,ou=People,dc=example,dc=com) dn " via LDAPI on 1.4.x takes approx 0,01-0,03 sec.
This user is member of approx. 500 groups.
 
I tested two migration methods:
1. via replication
After initializing replica, the same query takes about _8_ sec.
So I reindexed db (dsctl .. db2index) and get durations for the query from 2-3 sec.
 
2. via ldif export/import
after importing, the same query takes about 2-3 sec
 
But even with 2-3 sec, we talk about 2.x perfomance ten time slower than 1.4.x.
Is this a know issue? I compared all cache-settings and found no differences.
I have no more ideas how to optimize this. Should we wait for 2.x when its adopted to new lmdb?
 
thanks
Claas
 
 
 
 
 
 
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