我运行完全相同的Python函数,一个作为Postgresql PL / Python,另一个作为通常的Python脚本在Postgresql之外运行.
令人惊讶的是,当我使用select * from pymax7(20000);调用Postgresql PL / Python时,它平均花费65秒,而当我调用通常的Python脚本python myscript.py 20000时,它平均需要48秒.计算运行查询和脚本10次的平均值.
是否应该有这样的差异? Postgresql RDBMS(PL / Python)中的Python如何在性能方面与Python之外的Python进行比较?
我在Ubuntu 12.04 64位上运行Postgresql 9.1和Python 2.7.
Postgresql PL / Python:
CREATE FUNCTION pymax7 (b integer)
RETURNS float
AS $$
a = 0
for i in range(b):
for ii in range(b):
a = (((i+ii)%100)*149819874987)
return a
$$LANGUAGE plpythonu;
Python:
import time
import sys
def pymax7 (b):
a = 0
for i in range(b):
for ii in range(b):
a = (((i+ii)%100)*149819874987) # keeping Python busy
return a
def main():
numIterations = int(sys.argv[1])
start = time.time()
print pymax7(numIterations)
end = time.time()
print "Time elapsed in Python:"
print str((end - start)*1000) + ' ms'
if __name__ == "__main__":
main()