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optimizes over and over until the tree is stabilized

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git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@144 014f5005-505e-4b48-8d0a-63407b615a7c
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LtWorf 2009-04-30 18:21:50 +00:00
parent 88efcf0b78
commit 444d3f9987
1 changed files with 5 additions and 2 deletions
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relational/optimizer.py
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@ -166,8 +166,11 @@ def general_optimize(expression):
'''This function performs general optimizations. Means that it will not need to '''This function performs general optimizations. Means that it will not need to
know the fields used by the relations''' know the fields used by the relations'''
n=tree(expression) #Gets the tree n=tree(expression) #Gets the tree
for i in optimizations.general_optimizations: total=1
print "Changes done: ", i(n) #Performs the optimization while total!=0:
total=0
for i in optimizations.general_optimizations:
total+=i(n) #Performs the optimization
return n.__str__() return n.__str__()
if __name__=="__main__": if __name__=="__main__":