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"""
Query 3, 'Local Item Suggestion'. Who is selling in OR, ID or CA in category
10, and for what auction ids? In CQL syntax::
SELECT Istream(P.name, P.city, P.state, A.id)
FROM Auction A [ROWS UNBOUNDED], Person P [ROWS UNBOUNDED]
WHERE A.seller = P.id
AND (P.state = `OR' OR P.state = `ID' OR P.state = `CA')
AND A.category = 10;
We'll implement this query to allow 'new auction' events to come before the
'new person' events for the auction seller. Those auctions will be stored until
the matching person is seen. Then all subsequent auctions for a person will use
the stored person record.
"""
from __future__ import absolute_import
import logging
import apache_beam as beam
from apache_beam.testing.benchmarks.nexmark.models import nexmark_model
from apache_beam.testing.benchmarks.nexmark.queries import nexmark_query_util
from apache_beam.testing.benchmarks.nexmark.queries.nexmark_query_util import ResultNames
from apache_beam.transforms import trigger
from apache_beam.transforms import userstate
from apache_beam.transforms import window
from apache_beam.transforms.userstate import on_timer
[docs]def load(events, metadata=None):
num_events_in_pane = 30
windowed_events = (
events
| beam.WindowInto(
window.GlobalWindows(),
trigger=trigger.Repeatedly(trigger.AfterCount(num_events_in_pane)),
accumulation_mode=trigger.AccumulationMode.DISCARDING))
auction_by_seller_id = (
windowed_events
| nexmark_query_util.JustAuctions()
| 'query3_filter_category' >> beam.Filter(lambda auc: auc.category == 10)
| 'query3_key_by_seller' >> beam.ParDo(
nexmark_query_util.AuctionBySellerFn()))
person_by_id = (
windowed_events
| nexmark_query_util.JustPerson()
| 'query3_filter_region' >>
beam.Filter(lambda person: person.state in ['OR', 'ID', 'CA'])
| 'query3_key_by_person_id' >> beam.ParDo(
nexmark_query_util.PersonByIdFn()))
return ({
nexmark_query_util.AUCTION_TAG: auction_by_seller_id,
nexmark_query_util.PERSON_TAG: person_by_id,
}
| beam.CoGroupByKey()
| 'query3_join' >> beam.ParDo(
JoinFn(metadata.get('max_auction_waiting_time')))
| 'query3_output' >> beam.Map(
lambda t: {
ResultNames.NAME: t[1].name,
ResultNames.CITY: t[1].city,
ResultNames.STATE: t[1].state,
ResultNames.AUCTION_ID: t[0].id
}))
[docs]class JoinFn(beam.DoFn):
"""
Join auctions and person by person id and emit their product one pair at
a time.
We know a person may submit any number of auctions. Thus new person event
must have the person record stored in persistent state in order to match
future auctions by that person.
However we know that each auction is associated with at most one person, so
only need to store auction records in persistent state until we have seen the
corresponding person record. And of course may have already seen that record.
"""
AUCTIONS = 'auctions_state'
PERSON = 'person_state'
PERSON_EXPIRING = 'person_state_expiring'
auction_spec = userstate.BagStateSpec(AUCTIONS, nexmark_model.Auction.CODER)
person_spec = userstate.ReadModifyWriteStateSpec(
PERSON, nexmark_model.Person.CODER)
person_timer_spec = userstate.TimerSpec(
PERSON_EXPIRING, userstate.TimeDomain.WATERMARK)
def __init__(self, max_auction_wait_time):
self.max_auction_wait_time = max_auction_wait_time
[docs] def process(
self,
element,
auction_state=beam.DoFn.StateParam(auction_spec),
person_state=beam.DoFn.StateParam(person_spec),
person_timer=beam.DoFn.TimerParam(person_timer_spec)):
# extract group with tags from element tuple
_, group = element
existing_person = person_state.read()
if existing_person:
# the person exists in person_state for this person id
for auction in group[nexmark_query_util.AUCTION_TAG]:
yield auction, existing_person
return
new_person = None
for person in group[nexmark_query_util.PERSON_TAG]:
if not new_person:
new_person = person
else:
logging.error(
'two new person wtih same key: %s and %s' % (person, new_person))
continue
# read all pending auctions for this person id, output and flush it
pending_auctions = auction_state.read()
if pending_auctions:
for pending_auction in pending_auctions:
yield pending_auction, new_person
auction_state.clear()
# output new auction for this person id
for auction in group[nexmark_query_util.AUCTION_TAG]:
yield auction, new_person
# remember person for max_auction_wait_time seconds for future auctions
person_state.write(new_person)
person_timer.set(new_person.date_time + self.max_auction_wait_time)
# we are done if we have seen a new person
if new_person:
return
# remember auction until we see person
for auction in group[nexmark_query_util.AUCTION_TAG]:
auction_state.add(auction)
[docs] @on_timer(person_timer_spec)
def expiry(self, person_state=beam.DoFn.StateParam(person_spec)):
person_state.clear()