At Wednesday 8/11/2006 07:18, Farraige wrote:
for row_t1 in t1:
for row_t2 in t2:
if [row_t1[i] for i in keyColumns] == [row_t2[j] for j
in keyColumns]:
# the keys are the same
for colName in columnsToBeUpdated:
row_t1[colName] = row_t2[colName]
# go outside the inner loop - we found a row with
# the same key in the table
break
In my algorithm I have 2 for loops and I have no idea how to optimise
it (maybe with map? )
I call this method for very large data and the performance is a
critical issue for me :(
def getkey(row):
return tuple([row[i] for i in keyColumns])
Sort both tables using .sort(key=getkey); then traverse both in
paralell like in classic merge; in 1 pass you get the job done (not
counting the two initial sorts)
--
Gabriel Genellina
Softlab SRL
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