Source code for examples.dogpile_caching.helloworld
"""Illustrate how to load some data, and cache the results."""from.caching_queryimportFromCachefrom.environmentimportcachefrom.environmentimportSessionfrom.modelimportPerson# load Person objects. cache the result in the "default" cache regionprint("loading people....")people=Session.query(Person).options(FromCache("default")).all()# remove the Session. next query starts from scratch.Session.remove()# load again, using the same FromCache option. now they're cached,# so no SQL is emitted.print("loading people....again!")people=Session.query(Person).options(FromCache("default")).all()# Specifying a different query produces a different cache key, so# these results are independently cached.print("loading people two through twelve")people_two_through_twelve=(Session.query(Person).options(FromCache("default")).filter(Person.name.between("person 02","person 12")).all())# the data is cached under string structure of the SQL statement, *plus*# the bind parameters of the query. So this query, having# different literal parameters under "Person.name.between()" than the# previous one, issues new SQL...print("loading people five through fifteen")people_five_through_fifteen=(Session.query(Person).options(FromCache("default")).filter(Person.name.between("person 05","person 15")).all())# ... but using the same params as are already cached, no SQLprint("loading people two through twelve...again!")people_two_through_twelve=(Session.query(Person).options(FromCache("default")).filter(Person.name.between("person 02","person 12")).all())# invalidate the cache for the three queries we've done. Recreate# each Query, which includes at the very least the same FromCache,# same list of objects to be loaded, and the same parameters in the# same order, then call invalidate().print("invalidating everything")cache.invalidate(Session.query(Person),{},FromCache("default"))cache.invalidate(Session.query(Person).filter(Person.name.between("person 02","person 12")),{},FromCache("default"),)cache.invalidate(Session.query(Person).filter(Person.name.between("person 05","person 15")),{},FromCache("default","people_on_range"),)