函数page_get_space_id

#define FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID  34

/*************************************************************//**
Gets the tablespace identifier.
@return    space id */
UNIV_INLINE
ulint
page_get_space_id(
/*==============*/
    const page_t*    page)    /*!< in: page */
{
    ut_ad(page == page_align((page_t*) page));
    return(mach_read_from_4(page + FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID));
}