google app engine - GAE, memcache before DB update -


i have troubles memcache , gae db operations. if update memcache rigth after db operations, x.put(), example, memcache function return old value. if use sleep(), cache more correct, not right, in opinion

sleep(0.2)  data = picture.all().order('-created').fetch(300) memcache.set('pictures_all', data)

what need do, correct memcache?

answer: need use parent query, picture entities must have same parent, strong consistant results

data = picture.all().order('-created').ancestor(main_key()).fetch(300) memcache.set('pictures_all', data)

if have data, update 1 entry in memcache, no need retrieve memcache. like

data.put() memcache.set(key, data)

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