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/* postgres can not */
/* syntax version 1 */
$script = @@
import heapq
import json
N_SMALLEST = 3
def create(item):
return [item]
def add(state, item):
heapq.heappush(state, item)
return heapq.nsmallest(N_SMALLEST, state)
def merge(state_a, state_b):
merged = heapq.merge(state_a, state_b)
return heapq.nsmallest(N_SMALLEST, merged)
def get_result(state):
result = heapq.nsmallest(N_SMALLEST, state)
return '%d smallest items: %s' % (
N_SMALLEST,
', '.join(map(str, result))
)
def serialize(state):
return json.dumps(state)
def deserialize(serialized):
return json.loads(serialized)
@@;
$create = Python3::create(Callable<(Int64)->Resource<Python3>>, $script);
$add = Python3::add(Callable<(Resource<Python3>,Int64)->Resource<Python3>>, $script);
$merge = Python3::merge(Callable<(Resource<Python3>,Resource<Python3>)->Resource<Python3>>, $script);
$get_result = Python3::get_result(Callable<(Resource<Python3>)->String>, $script);
$serialize = Python3::serialize(Callable<(Resource<Python3>)->String>, $script);
$deserialize = Python3::deserialize(Callable<(String)->Resource<Python3>>, $script);
SELECT UDAF(
DISTINCT item,
$create,
$add,
$merge,
$get_result,
$serialize,
$deserialize
) FROM (
SELECT
CAST(LENGTH(value) AS Int64) AS item
FROM plato.Input
);
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