Misa & Ben, Thanks. I guess I overlooked that in the docs. I did see the part about the 65KB. I don't see my labels getting overly long. I'll be fine with Herbs_Spices. I make up the labels myself, so it's really no big deal.
Alexander & Bryan - Many thanks for the help! On Sat, Feb 23, 2013 at 3:13 PM, Ben Morrow <b...@morrow.me.uk> wrote: > Quoth parri...@gmail.com (Don Parris): > > > > Is it possible to use spaces in the ltree path, like so: > > TOP.Groceries.Food.Herbs & Spices > > > > Or do the elements of the path have to use underscores and dashes? > > From the docs: > > | A label is a sequence of alphanumeric characters and underscores (for > | example, in C locale the characters A-Za-z0-9_ are allowed). Labels > | must be less than 256 bytes long. [...] > | > | A label path is a sequence of zero or more labels separated by dots, > | for example L1.L2.L3, representing a path from the root of a > | hierarchical tree to a particular node. The length of a label path > | must be less than 65Kb, but keeping it under 2Kb is preferable. > > If you need to store non-alphanumeric labels, one answer (as long as > they aren't too long) would be to use URL-encoding, like > > TOP.Groceries.Food.Herbs_20_26_20Spices > > Of course, you would need to encode _ as well, and you would need to be > sure the labels weren't going to come out too long. Another alternative > would be to MD5 each label and use (say) the first 10 bytes of that MD5 > in hex as the ltree label. (Annoyingly there's only one > non-alphanumeric, so you can't use base64.) If you were going to do that > you would need to consider the possibility of an attacker arranging a > hash collision: I don't know where you're labels come from, so I don't > know if this would be an issue. > > Ben > > -- D.C. Parris, FMP, Linux+, ESL Certificate Minister, Security/FM Coordinator, Free Software Advocate http://dcparris.net/ <https://www.xing.com/profile/Don_Parris><http://www.linkedin.com/in/dcparris> GPG Key ID: F5E179BE
