RLL in data sharing

get & p-lock page

lock row

p-lock & latch page

test to see if existed most current copy of page, if yes then refresh page

update page

release latch

commit

    write changed page

    release row lock

write changed page into GBP可以发生在commit之前(到了一个check point)，但是必须在release latch之后，此时该条record仍然是收保护的，因为上面有row lock,直到commit(commit会把GBP里的内容回写到DASD上）过后才会释放。