For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:messenger:matrix/openSUSE_Tumbleweed/home:ecsos:messenger:matrix.repo
zypper refresh
zypper install lmdbxx
For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:messenger:matrix/openSUSE_Slowroll/home:ecsos:messenger:matrix.repo
zypper refresh
zypper install lmdbxx
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:messenger:matrix/16.0/home:ecsos:messenger:matrix.repo
zypper refresh
zypper install lmdbxx
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:ecsos:messenger:matrix/15.6/home:ecsos:messenger:matrix.repo
zypper refresh
zypper install lmdbxx