gentoo-overlay/dev-db/postgresql/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
    <herd>postgresql</herd>
    <use>
        <flag name='pg_legacytimestamp'>
            Use double precision floating-point numbers instead of 64-bit
            integers for timestamp storage.
        </flag>
        <flag name='server'>
            Disable to build and install the clients and libraries only.
        </flag>
        <flag name='uuid'>
            Enable server side UUID generation (via
            <pkg>dev-libs/ossp-uuid</pkg>).
        </flag>
    </use>
</pkgmetadata>