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Implemented swap_union_renames general optimization

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git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@177 014f5005-505e-4b48-8d0a-63407b615a7c
This commit is contained in:
LtWorf 2009-05-23 08:21:43 +00:00
parent 644d96dc63
commit dac465779c
2 changed files with 50 additions and 5 deletions
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53
relational/optimizations.py
View File

@ -160,9 +160,54 @@ def selection_inside_projection(n):
changes+=selection_inside_projection(n.left)
return changes
def swap_union_renames(n):
'''This function locates things like
ρ a➡b(R) ᑌ ρ a➡b(Q)
and replaces them with
ρ a➡b(R ᑌ Q).
Does the same with subtraction and intersection'''
#TODO document into the wiki
changes=0
if n.name in ('-','ᑌ','ᑎ') and n.left.name==n.right.name and n.left.name=='ρ':
l_vars={}
for i in n.left.prop.split(','):
q=i.split('➡')
l_vars[q[0].strip()]=q[1].strip()
r_vars={}
for i in n.right.prop.split(','):
q=i.split('➡')
r_vars[q[0].strip()]=q[1].strip()
if r_vars==l_vars:
changes=1
#Copying self, but child will be child of renames
q=optimizer.node()
q.name=n.name
q.kind=optimizer.BINARY
q.left=n.left.child
q.right=n.right.child
n.name='ρ'
n.kind=optimizer.UNARY
n.child=q
n.prop=n.left.prop
n.left=n.right=None
#recoursive scan
if n.kind==optimizer.UNARY:
changes+=swap_union_renames(n.child)
elif n.kind==optimizer.BINARY:
changes+=swap_union_renames(n.right)
changes+=swap_union_renames(n.left)
return changes
def futile_renames(n):
'''This function removes redoundant subsequent renames'''
#TODO document in the wiki
'''This function purges renames like id->id'''
changes=0
if n.name=='ρ':
@ -209,7 +254,7 @@ def futile_renames(n):
return changes
def subsequent_renames(n):
'''This function removes redoundant subsequent renames'''
'''This function removes redoundant subsequent renames joining them into one'''
'''Purges renames like id->id Since it's needed to be performed BEFORE this one
so it is not in the list with the other optimizations'''
@ -456,5 +501,5 @@ def selection_and_product(n,rels):
changes+=selection_and_product(n.left,rels)
return changes
general_optimizations=[duplicated_select,down_to_unions_subtractions_intersections,duplicated_projection,selection_inside_projection,subsequent_renames,swap_rename_select,futile_union_intersection_subtraction]
general_optimizations=[duplicated_select,down_to_unions_subtractions_intersections,duplicated_projection,selection_inside_projection,subsequent_renames,swap_rename_select,futile_union_intersection_subtraction,swap_union_renames]
specific_optimizations=[selection_and_product]

2
relational/optimizer.py
View File

@ -284,7 +284,7 @@ if __name__=="__main__":
#print n
#print n.result_format(rels)
a=general_optimize("ρ index➡index(ρ index➡id(ρ index➡index(σ index==3(ρ id➡index (people)))))")
a=general_optimize("ρ id➡ciao(R) - ρ id➡ciao(Q) ")
#a=general_optimize("σ i==2 (σ b>5 (d))")
print a
#print node(a)