mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-28 11:35:19 -04:00
Mike Bayer
63 lines
2.4 KiB
Python
63 lines
2.4 KiB
Python
"""helloworld.py
|
|
|
|
Illustrate how to load some data, and cache the results.
|
|
|
|
"""
|
|
|
|
from .environment import Session
|
|
from .model import Person
|
|
from .caching_query import FromCache
|
|
|
|
# load Person objects. cache the result in the "default" cache region
|
|
print("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 SQL
|
|
print("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")
|
|
Session.query(Person).options(FromCache("default")).invalidate()
|
|
Session.query(Person).\
|
|
options(FromCache("default")).\
|
|
filter(Person.name.between("person 02", "person 12")).invalidate()
|
|
Session.query(Person).\
|
|
options(FromCache("default", "people_on_range")).\
|
|
filter(Person.name.between("person 05", "person 15")).invalidate()
|
|
|