The document tree is still slow on MySql

select xwikipage0_.reference as col_0_0, xwikipage0_.terminal as col_1_0

    from (
        select XWS_REFERENCE as reference, false as terminal, XWS_NAME as name, XWS_PARENT as parent, XWS_HIDDEN as hidden
            from xwikispace
        union all
        select XWD_FULLNAME as reference, true as terminal, XWD_NAME as name, XWD_WEB as parent, XWD_HIDDEN as hidden
            from xwikidoc
            where XWD_TRANSLATION = 0 and XWD_NAME <> 'WebHome'
    ) xwikipage0_ left outer join (
        select case when XWD_NAME = 'WebHome' then XWD_WEB else XWD_FULLNAME end as reference,
               case when XWD_NAME = 'WebHome' then false else true end as terminal,
               nullif(XWD_TITLE, '') as title, XWD_LANGUAGE as locale, XWD_DEFAULT_LANGUAGE as defaultLocale
            from xwikidoc
    ) translatio1_ on xwikipage0_.reference=translatio1_.reference and xwikipage0_.terminal=translatio1_.terminal and (translatio1_.locale='') left outer join (
        select case when XWD_NAME = 'WebHome' then XWD_WEB else XWD_FULLNAME end as reference,
               case when XWD_NAME = 'WebHome' then false else true end as terminal,
               nullif(XWD_TITLE, '') as title, XWD_LANGUAGE as locale, XWD_DEFAULT_LANGUAGE as defaultLocale
            from xwikidoc
    ) translatio2_ on xwikipage0_.reference=translatio2_.reference and xwikipage0_.terminal=translatio2_.terminal and (translatio2_.locale='en')

    where xwikipage0_.parent='Test' and xwikipage0_.hidden<>1

    order by lower(coalesce(translatio2_.title, translatio1_.title, xwikipage0_.name)),
             coalesce(translatio2_.title, translatio1_.title, xwikipage0_.name)

    limit 15