>> I'm searching for an optimized Levenshtein Distance like Postgresql's. My >> problem is that I want to compare strings with a length over 255 characters. >> Does anyone know a solution?
> I'm not sure there is anything different from what you've found in > core/contribs. But you can always use pg/plpython or pg/plperl procedure > with some external library calculating the distance.
Well, you could just rebuild the fuzzystrmatch module with a different value for MAX_LEVENSHTEIN_STRLEN. The comments in the code note that the comparison cost is roughly O(N^2) in the string length, and the reason for having a limit at all is to ensure the function runtime doesn't get out of hand --- but it seems likely to me that 255 is an unnecessarily conservative limit. If you wanted to do a few tests and report back on just how slow it can get, we might be persuaded to raise the stock setting.
regards, tom lane
I've checked that and I think we could raise the limit without any problem
I've set
#define MAX_LEVENSHTEIN_STRLEN 255 * 255
I was using the levenshtein function comparing two strings of the same length
