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"""
Query 7, 'Highest Bid'. Select the bids with the highest bid price in the
last minute. In CQL syntax::
SELECT Rstream(B.auction, B.price, B.bidder)
FROM Bid [RANGE 1 MINUTE SLIDE 1 MINUTE] B
WHERE B.price = (SELECT MAX(B1.price)
FROM BID [RANGE 1 MINUTE SLIDE 1 MINUTE] B1);
We will use a shorter window to help make testing easier. We'll also
implement this using a side-input in order to exercise that functionality.
(A combiner, as used in Query 5, is a more efficient approach.).
"""
import apache_beam as beam
from apache_beam.testing.benchmarks.nexmark.queries import nexmark_query_util
from apache_beam.transforms import window
[docs]def load(events, metadata=None, pipeline_options=None):
# window bids into fixed window
sliding_bids = (
events
| nexmark_query_util.JustBids()
| beam.WindowInto(window.FixedWindows(metadata.get('window_size_sec'))))
# find the largest price in all bids per window
max_prices = (
sliding_bids
| beam.Map(lambda bid: bid.price)
| beam.CombineGlobally(max).without_defaults())
return (
sliding_bids
| 'select_bids' >> beam.ParDo(
SelectMaxBidFn(), beam.pvalue.AsSingleton(max_prices)))
[docs]class SelectMaxBidFn(beam.DoFn):
[docs] def process(self, element, max_bid_price):
if element.price == max_bid_price:
yield element