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Re: Binary property list efficiency issue


On 20 Jan 2006, at 07:16, Laurence Harris wrote:

Here are some times I got in testing. Property list has a small header which
is the same size for every list and a main array. All times are the time
spent in CFPropertyListWriteToStream:

1,538 items:
binary 1.65
XML 0.317

8,365 items:
binary 63.58
XML 0.933

31,041 items:
binary 1499.033 secs
XML 3.583 secs

The XML times go up linearly. The binary times appear to be going up
exponentially. This makes the binary format completely unusable for large
lists with its current implementation. I can't ask users to wait 25 minutes
while I save a file. 

Larry,

This reminds me of a similar situation with Cocoa Archiving. I think the Binary version is trying to only add each 'duplicated' value for everything only once and then just inserting a reference to the original each time a duplicate is encountered. The plain version is obviously not allowed to do this. Hence as the list gets bigger, the time to compare each item against all the others grows exponentially. If you want to save space, I would suggest creating a text property list into memory and then using zlib to compress that down. I suspect that will be a lot quicker, if not maybe so small overall.


Matt



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