user search does not retrieve all users in system

[amiraelsayed]

if I am logged in using
username : james
password : 123456
users that comes from martix server are

Sameh/@Sameh:domain.com
Walid/@walid:domain.com
madonna/@MADONNA:domain.com

if I am logged in using
username : john
password : 123456
users that comes from martix server are

Sameh/@Sameh:domain.com
Walid/@walid:domain.com
madonna/@MADONNA:domain.com
Habib/@habib:domain.com
elias/@elias:domain.com
nour/@nour:domain.com
wiliam/@wiliam:domain.com

if I am logged in using
username : nour
password : 123456
users that comes from martix server are

john/@john:domain.com
Sameh/@Sameh:domain.com
Walid/@walid:domain.com
madonna/@MADONNA:domain.com
elias/@elias:domain.com
wiliam/@wiliam:domain.com

why that could happen?

[amiraelsayed]

I am using
getSession(context).eventsApiClient.searchUsers("domain", 100, null, userFoundCallback)
in android matrix sdk

[bmarty]

According to https://matrix.org/docs/spec/client_server/latest#post-matrix-client-r0-user-directory-search, the users returned depends on the fact that the logged user shares room(s) with them:

The homeserver may determine which subset of users are searched, however the homeserver MUST at a minimum consider the users the requesting user shares a room with and those who reside in public rooms (known to the homeserver). The search MUST consider local users to the homeserver, and SHOULD query remote users as part of the search.